History questions Essay Example | Topics and Well Written Essays - 1500 words

History questions - Essay Example Abraham Lincoln told â€Å"enemy is at your door, wait not to meet him at your hearthstone, meet him at the doorsill, and drive him from the temple of liberty, or pull down its pillars and involve him in a common ruin† (McPherson 212). This should be considered as evidence that our country is not safe anymore. Abraham Lincoln also mentioned that he thoroughly disliked to comment on the various tactics employed by historical leaders who played an instrumental role in earlier wars. Government always must be â€Å"of the people, by the people and for the people† and victory always must be â€Å"an anti slavery triumph† (McPherson 218). Jefferson Davis strongly disagreed on excessive individualism that were ruling the states. He pointed out that this kind of extreme individualism won’t bring any good to the state. Instead, it will only create neglect towards teamwork. He also emphasized that â€Å"war meant it’s for all and not for single†. This means, war is always for a group of people and not for a single person. He told â€Å"each state has the right of revolution† (McPherson 240). Political revolution or any kind of revolution always placed the state in a crucial, authori tative position and the right of revolution is for everyone. 2. If as Mr. Sparks contends what is Past is prologue, there is much in the Civil War Era that is relevant to your lives today. Please provide 3 examples of how a study of The Civil War helps you understand the United States in 2010. If a civil war breaks out in the Unites States in 2010, it, will, perhaps mark the end of this country. There would be violence, bloodshed, riots and insurgencies all over the country, leading to loss of millions of human lives as well as the ultimate breakdown of the country’s vast social and economic infrastructure. A study of the civil war has helped us to understand the

Ang Katay Essay Example for Free

Ang Katay Essay Riting a biography is hard work. Whether its analyzing the mindset of philosophers who died many millennia ago, or encapsulating the lasting impact of the life of an American president, its always a great challenge. Fortunately, youre not alone on your quest to write an A essay. Couselling on Smoking Cessation Therapeutics II: Counselling on Smoking Cessation Nancy Unsworth March 18, 2011 Counselling on Smoking Cessation For the purpose of this assignment, this client will Premium 4130 Words 17 Pages Jack London Jack London Jack London is one of the most famous American writers. He wrote many great books over his short lifetime. Many of his stories are about animals and nature Premium 2680 Words 11 Pages Mary Shelley: Life of Literature I, the miserable and the abandoned, am an abortion, to be spurned at, and kicked, and trampled on (SparkNote on Frankenstein). This famous quote said by Frankenstein, in Premium 1429 Words 6 Pages Chief Lieutenant of the Tuskegee Machine Gaitor, Bridget Word Count: 1,859 The Chief Lieutenant of the Tuskegee Machine by David H. Jackson Jr. exemplifies the life of Charles Banks as Booker T. Washingtons Premium 1881 Words 8 Pages John Steinbecks Greatest Accomplishments John Steinbeck, born in 1902 in Salinas California to John Ernst and Olive Hamilton Steinbeck, became one of the greatest American writers of his century. Growing up Premium 973 Words 4 Pages The Consumer Appeal of Underdog Branding.Docx

Unity Among Student Scientists :: Personal Narrative Essays

Unity Among Student Scientists This summer I had the opportunity to attend the APEC Youth Festival in Singapore. On July 23, I arrived in San Francisco at the Marriott to gather with 19 other students from around the United States. The purpose of this gathering was to discuss our future trip to Singapore and to get acquainted with each other before we left. APEC stands for Asian Pacific Economic Cooperation. The purpose of the APEC Youth Festival is to bring unity among other student scientists from all around the world. Students who attended the Festival came from eleven different economies and all brought a unique culture with them. The festival included various activities, such as a cultural exchange, science and technology lectures, a youth science summit, a farewell party, and tons more. Every activity at the science festival was a learning experience. Two days of cultural performances were held, in which each of the economies put on a five-minute performance representing their culture. My favorite of these was the drum performance by the Koreans, but each of the dances by the many Asian cultures were equally good. And the U.S. economy's performance . . . who could forget about that? Did anyone really know what they were doing? Although the U.S. economy's cultural presentation definitely didn't turn out as expected, we gave the audience a good laugh and started a new craze among the other attendees: the shark song. The students' cultures were reflected not only in the two cultural presentations that were held, but also in the way they presented themselves at the conference. By attending the AYSF, I received a little taste of different cultures stretching all the way from Australia to Thailand. The real cultural experience came from the learning about the laws, languages and customs of Singapore. In Singapore, there are many laws that are strictly enforced, such as no chewing gum, no picking flowers, mandatory flushing of toilets and no bird feeding. The most outrageous law is the "no peeing in elevators" law. By the cleanliness of Singapore, one could tell the laws are enforced. In Singapore, just about every student that I had the opportunity to meet spoke two different languages. All spoke English and another Asian language. I had the opportunity to get to know students that spoke Chinese, Malay, Indonesian, Thai, and many more.

Grignard Reagent

1598 Organometallics 2009, 28, 1598–1605 CoVer Essay The Grignard Reagents Dietmar Seyferth Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 ReceiVed February 4, 2009 During the past 100 years the Grignard reagents probably have been the most widely used organometallic reagents. Most of them are easily prepared in ethereal solution (usually diethyl ether or, since the early 1950s, THF) by the reaction of an organic halide with metallic magnesium (eq 1).Table 1. Composition of Diethyl Ether Solutions of Various Grignard Reagents at Equilibrium (in mol %), 2RMgX h R2Mg + MgX2a RX in RX + Mg reacn CH3I C2H5I C2H5Br C2H5Cl n-C3H7I n-C3H7Br n-C3H7Cl C6H5I C6H5Br a RMgX 87. 0 43. 0 41. 0 15. 0 24. 0 24. 0 17. 0 38. 0 30. 0 R2Mg ) MgX2 6. 5 28. 5 29. 5 42. 5 38. 0 38. 0 41. 5 31. 0 35. 0 RX + Mg f RMgX (X ) Cl, Br, I) (1) Most of them are stable in ethereal solution (although atmospheric moisture and oxygen should be excluded) and in gene ral are quite reactive.Discovered by Victor Grignard at the University of Lyon in France in 1900,1 their ease of preparation and their broad applications in organic and organometallic synthesis made these new organomagnesium reagents an instant success. The importance of this contribution to synthetic chemistry was recognized very early, and for his discovery Grignard was awarded a Nobel Prize in Chemistry in 1912. Our cover molecule is the monomeric ethylmagnesium bromide bis(diethyl etherate) (1), whose solid-state molecular structure was determined by an X-ray diffraction study by Lloyd Guggenberger and RobertRundle in 1964 using crystals isolated from a diethyl ether solution of a C2H5Br/Mg reaction mixture by slow cooling with a stream of cold gaseous nitrogen. 2-4 Adapted from: Schlenk, W. , Jr. Ber. Dtsch. Chem. Ges. 1931, 64, 734. Wilhelm Schlenk and his son discovered 80 years ago, more than one magnesium-containing species exists in the diethyl ether solution of a Grignard reagent. 5 A redistribution of the substituents on magnesium takes place, and the RMgX species ends up in equilibrium with the two symmetrical species, the diorganomagnesium and the magnesium dihalide: the â€Å"Schlenk Equilibrium† (eq 2). 2RMgX h R2Mg + MgX2 (2) Generally written as â€Å"RMgX† in textbooks, monographs and research papers, the Grignard reagents in ethereal solution are more complicated than this simple formula indicates. As (1) (a) Grignard, V. Compt. rend. Hebd. Seances Acad. Sci. 1900, 130, ? 1322. (b) Grignard, V. Dissertation â€Å"Theses sur les combinaisons organo` magnesienes mixtes et leur application a des syntheses†, University of Lyon, ` ` Lyon, France, 1901. (2) (a) Guggenberger, L. J. ; Rundle, R. E. J. Am. Chem. Soc. 1964, 86, 5344. (b) Guggenberger, L. J. ; Rundle, R. E. J. Am. Chem. Soc. 1968, 90, 5375. 3) A crystalline solid, CH3MgI  · (n-C5H11)2O, was isolated and identi? ed as such by elemental analysis (Mg and I) in 1908 : Zerewitinoff, Th. Ber. Dtsch. Chem. Ges. 1908, 41, 2244. The oxonium structure The species that contain Mg-halogen bonds can be precipitated from Grignard reagent solutions in diethyl ether by the addition of 1,4-dioxane. An insoluble, polymeric 1,4-dioxane adduct is formed, leaving behind a solution of R2Mg5sa useful preparation of dialkyl- and diarylmagnesium reagents. 6 Wilhelm Schlenk, Jr. analyzed the 1,4-dioxane precipitations from a number of Grignard reagent solutions. Assuming that the precipitation is essentially instantaneous, i. e. , that the calculated R2Mg, MgX2, and RMgX percentages re? ect the actual composition of the Grignard reagent solution at equilibrium, Schlenk reported the compositions collected in Table 1. Direct evidence (5) Schlenk, W. ; Schlenk, W. , Jr. Ber. Dtsch. Chem. Ges. 1929, 62, 920. (6) (a) Cope, A. C. J. Am. Chem. Soc. 1935, 57, 2238. (b) As Erwin Weiss found, evaporation of diethyl ether solutions of methyl- and ethylmagnesium bromide and chl oride at reduced pressure followed by heating of the colorless solid residues at ca. 00  °C and 0. 001 mmHg for several hours gave a mixture of the respective pure, solvent-free, polymeric R2Mg compounds and magnesium halides. The solid MgCl2 thus obtained differed from a sample obtained from a MgCl2 melt in that its lattice showed a strong stacking disorder. This form of MgCl2 had an extremely high surface area: Weiss, E. Chem. Ber. 1965, 98, 2805. (7) Schlenk, W. , Jr. Ber. Dtsch. Chem. Ges. 1931, 64, 734 Further additions to the examples in Table 1 were soon thereafter reported by other workers: (a) Noller, C. R. ; Hilmer, F. B. J. Am. Chem. Soc. 1932, 54, 2503. (b) Johnson, G. O. Adkins, H. J. Am. Chem. Soc. 1932, 54, 1943. (c) Cope, A. C. J. Am. Chem. Soc. 1934, 56, 1578. was written for this compound. Earlier workers had isolated noncrystalline solid samples of etherates, e. g. , C2H5MgI  · (C2H5)2O and RMgI  · 2(C2H5)2O. (4) Other early Grignard reagent crystal structur es: (a) Stucky, G. D. ; Rundle, R. E. J. Am. Chem. Soc. 1964, 86, 4825 (C6H5MgBr  · 2Et2O). (b) Vallino, M. J. Organomet. Chem. 1969, 20, 1 (CH3MgBr  · 3THF). . 10. 1021/om900088z CCC: $40. 75 ? 2009 American Chemical Society Publication on Web 03/16/2009 Organometallics, Vol. 28, No. 6, 2009 1599 Figure 1.Association of several Grignard compounds in tetrahydrofuran (J. Am. Chem. Soc. 1969, 91, 3847. ). that solutions of â€Å"CH3MgBr† in diethyl ether contain CH3MgBr and (CH3)2Mg was obtained by Ashby and co-workers by means of 1H NMR spectroscopic measurements at -105  °C. Solutions of â€Å"t-butylmagnesium chloride† in diethyl ether also were studied. 8 The tendency of the halide substituents in the RMgX and MgX2 species present in ethereal solution at equilibrium to form bridges between magnesium atoms, Mg-X-Mg, in a Lewis base/Lewis acid type interaction further complicates the nature of the Grignard reagent in ethereal solvents.In a very thorough study of the association factors of various Grignard reagents in diethyl ether and THF by careful ebullioscopic molecular weight measurements, Eugene Ashby and Frank Walker at the Georgia Institute of Technology found that monomeric, dimeric, and higher oligomeric species were present, depending on the solvent and the halogen and the organic substituents on the magnesium atom. 9 Included in this study along with data for the â€Å"RMgX† solutions were data for a few R2Mg compounds and for the magnesium dihalides.As Figure 1 shows, the observed association factor (the i value is the apparent molecular weight divided by the formula weight of the monoetherate) shows that the Grignard reagents and (C6H5)2Mg are close to monomeric in the relatively strong Lewis basic THF. The picture is quite different in diethyl ether solution (Figures 2 and 3), with association factors of 1 to nearly 4 for solute concentrations up to ca. 3 molal. It is not clear what these i values mean in terms of the a ctual species present in these solutions.On the assumption that the Schlenk equilibrium is operative in all cases, in view of the presence of a signi? cant concentration of MgX2, one cannot expect only simple solvated species of type i(R)Mg-X] n [ i (average n ) i). Toney and Stucky isolated crystals of a dimeric species, 2, from a solution of â€Å"C2H5MgBr† in di-n-butyl ether by addition of this solution to triethylamine. 10 The molecular Figure 2. Association of alkylmagnesium chlorides in diethyl ether. Demonstration of importance of halogen vs R group in determining the form of association in diethyl ether (J. Am. Chem. Soc. 1969, 91, 3848. ).Figure 3. Association of several alkyl- and arylmagnesium bromides and iodides and related magnesium compounds in diethyl ether (J. Am. Chem. Soc. 1969, 91, 3848. ). structure, as determined by X-ray analysis, contained a double Br bridge with the ethyl groups in a trans arrangement. That (8) In â€Å"CH3MgBr† solutions in d iethyl ether: (a) Ashby, E. C. ; Parrish, G. ; Walker, F. Chem. Commun. 1969, 1464. (b) â€Å"(CH3)3CMgCl† solutions in diethyl ether at-26  °C: Parris, G. ; Ashby, E. C. J. Am. Chem. Soc. 1971, 93, 1206. (9) (a) Walker, F. W. ; Ashby, E. C. J. Am. Chem. Soc. 1969, 91, 3845. (b) Ashby, E. C. Bull. Soc.Chim. Fr. 1972, 2133 (review, in English). (c) Meisenheimer, J. ; Schlichenmaier. Ber. Dtsch. Chem. Ges. 1928, 61 (an earlier, similar, but more limited study in diethyl ether). more complicated structures can be present in an â€Å"RMgX† solution in diethyl ether was demonstrated by the determination of the X-ray crystal structure of a crystalline compound obtained from a THF solution of â€Å"C2H5MgCl† of composition C2H5Mg2Cl3. This compound was not a simple Cl-bridged dimer, as the empirical formula might suggest. Actually, it was a tetramer (Figure 4) in which the Mg atoms have a coordination number greater than 4. 1 There is a caveat, however: the species t hat crystallizes from a Grignard reagent solution does not necessarily directly re? ect what species are swimming around in the solution. The crystalline solid shown in Figure 4 could well have self-assembled during the crystallization process by combination of two molecules of the C2H5Mg2Cl3 dimer and not been present in solution at all. Even in the case of monomeric â€Å"RMgX† in THF solution, the Schlenk equilibrium will be operative and the strongly Lewis basic THF apparently prevents halide bridging between Mg atoms.Consequently, the (10) Toney, J. ; Stucky, G. D. Chem. Commun. 1967, 1168. (11) Toney, J. ; Stucky, G. D. J. Organomet. Chem. 1971, 28, 5. 1600 Organometallics, Vol. 28, No. 6, 2009 Scheme 1 Figure 4. Molecular structure of [C2H5Mg2Cl3(C4H8O)3]2, a tetrameric Grignard reagent. Modi? ed from Toney and Stucky (J. Organomet. Chem. 1971, 28, 15. (copyright 1971, with permission from Elsevier)). presence of monomeric RMgX, R2Mg, and MgX2, all solvated, would resu lt in the measurement of an association factor of 1, as Walker and Ashby observed.There are so many factors that bear on the question of the constitution of a given Grignard reagent in ethereal solutionsthe Lewis basicity and steric properties of the ether solvent, the electronegativity and size of the halogen atom in RMgX, the nature and steric properties of the organic substituent on the magnesium atom. These will affect the magnitude of the equilibrium constant of the Schlenk equilibrium and the extent of Mg-X-Mg bridging. For most applications in synthetic chemistry it will suf? ce to take the easy way outsto regard and to write the Grignard reagent as RMgX.There is another interesting and useful property of ethereal Grignard reagent solutions. The magnesium species are weak electrolytes in such solvents of low dielectric constant, and â€Å"RMgX† solutions conduct an electric current. 12 The electrolysis of solutions of organomagnesium halides was studied in some detail by Kondyrew at the State Research Institute in Leningrad13 and by Ward Evans and his students at Northwestern University. 14 During the electrolysis, magnesium species migrate both to the cathode and to the anode. Scheme 1 shows the simplest picture based on RMgX. Metallic magnesium is formed at the cathode. 12) The earliest report appears to be a 1912 French paper: Jolibois, P. Compt. rend. Hebd. Seances Acad. Sci. 1912, 155, 213. See also: Nelson, ? J. M. ; Evans, W. V. J. Am. Chem. Soc. 1917, 39, 82. (13) (a) Kondyrew, N. W. Ber. Dtsch. Chem. Ges. 1925, 58, 459. (b) Kondyrew, N. W. ; Manojew, D. P. Ber. Dtsch. Chem. Ges. 1925, 58, 464. (c) Kondyrew, N. W. Ber. Dtsch. Chem. Ges. 1928, 61, 208. (d) Kondyrew, N. W. ; Ssusi, A. K. Ber. Dtsch. Chem. Ges. 1929, 62, 1856. (14) The Evans group published many papers in J. Am. Chem. Soc. during the 1933-1942 period. See, for example: (a) Evans, W. V. ; Lee, F.H. J. Am. Chem. Soc. 1934, 56, 654. (b) Evans, W. V. ; Field, E. J. Am. Chem. Soc . 1936, 58, 720. (c) Evans, W. V. ; Braithwaite, D. J. Am. Chem. Soc. 1939, 61, 898. (d) Evans, W. V. ; Braithwaite, D. ; Field, E. J. Am. Chem. Soc. 1940, 62, 534. (e) Evans, W. V. ; Pearson, R. J. Am. Chem. Soc. 1942, 64, 2865. The alkyl radicals formed at the anode can undergo the usual alkyl radical processes of coupling (to R-R), disproportionation (to RH + R(-H)), or, if the anode is composed of a reactive metal such as zinc, aluminum, cadmium, or lead, they can attack the anode to form an organometallic compound.A graduate student of Evans, David G. Braithwaite, joined the Nalco Chemical Co. after he graduated and developed an electrolytic process for the commercialscale syntheses of tetramethyl- and tetraethyllead antiknock agents in which the respective alkyl Grignard reagents were electrolyzed in a mixed THF/diethylene glycol dimethyl ether solvent system using a lead anode and a steel cathode. 15 The reactions of the Grignard reagents with organic, organometallic, and ino rganic substrates and their applications are too numerous and varied to be covered here.Not only do they ? nd extensive use on a small to moderate scale in research laboratories but they also have been prepared and utilized on a large scale in diverse industrial processes. For the most part they react as nucleophilic reagents, as would be expected, on the basis of the polarity of the carbon-magnesium bond, C? –Mg? +. However, they also can undergo electron transfer reactions with appropriate electron-acceptor substrates. They are weak bases capable of deprotonating the stronger weak organic acids such as terminal acetylenes and cyclopentadiene.Their basicity can be enhanced (as can be the basicity of organolithium reagents) by the addition to RMgX solutions in ethers of additives such as hexamethylphosphoric triamide (HMPA) and N-methyl-2-pyrrolidinone (NMP) or alkali-metal alkoxides. All such information can be found in books devoted solely or in part to Grignard reagents. 1 6 Two special topics are of current interest and merit special mention. (1) The preparation of highly functionalized organomagnesium reagents by Paul Knochel and his co-workers at the University of Munich17 by means of halogen-magnesium exchange (e. . , eq 3). The availability of reagents such as 3-8 (which must be utilized at low temperature) has added a new and spectacular dimension to Grignard reagent chemistry. (2) The synthesis of ole? ns, styrenes, 1,3-dienes and biaryl derivatives by the crosscoupling of Grignard reagents with organic halides. The crosscoupling of Grignard reagents with vinylic halides was discovered by Morris Kharasch and Charles Fuchs at the University of Chicago Organometallics, Vol. 28, No. 6, 2009 1601 Table 2.Transition Metal Halide Catalyzed Homocoupling of Phenylmagnesium Iodidea metal halide FeCl2 CoBr2 NiBr2 RuCl3 RhCl3 PdCl2 OsCl3 IrCl3 a amt, mol 0. 01 0. 01 0. 03 0. 0036 0. 0036 0. 00566 0. 00275 0. 003 amt of C6H5MgI, mol 0. 03 0. 03 0. 095 0. 0 108 0. 013 0. 0163 0. 007 0. 01 yield of biphenyl, % 98 98 100 99 97. 5 98 53 28 Taken from: J. Am. Chem. Soc. 1939, 61, 957. in 1943 during the classic studies of Kharasch on the chemistry of Grignard reagents in the presence of transition-metal halides. 6b Kharasch and Fuchs found that arylmagnesium bromides in diethyl ether reacted readily with vinylic halides of type RCHdCHX and R2CdCHX (but not CH2dC(R)X) to give styrenes in 50-75% yield when the reactions were carried out in the presence of 5 mol % of CoCl2 (eq 4). 18It was reported that other metal halides (of iron, nickel, and chromium) also were effective catalysts of this cross-coupling reaction. Benzylmagnesium chloride also reacted in this manner with vinyl bromide to give PhCH2CHdCH2 in 75% yield.Alkylmagnesium halides such as cyclohexyl- and n-butylmagnesium bromide, on the other hand, gave only â€Å"small to negligible† yields of the expected coupling product. The ArMgBrderived biaryl usually was obtained as a byproduct in these reactions. Such homocoupling of arylmagnesium halides in the presence of a transition metal halide as well as copper and silver halides was a known reaction. It had been investigated in 1939 by Gilman and Lichtenwalter, who found that aryl Grignard reagents undergo homocoupling in the presence of ca. 0 mol % of various transition-metal halides in diethyl ether solution to give the respective biaryl in high yield in most cases (eq 5, Table 2). 19 The metal halide, in addition to being the needed catalyst precursor, also served as an oxidizing agent and, in some cases (CoBr2, NiCl2, RhCl3), formation of a black solid indicated complete reduction to the metal. not occur in the absence of the organic halide but in its presence was vigorously exothermic. The added organic halide was only partially consumed and did not show up in the biaryl product.When p-bromotoluene was added to a phenylmagnesium bromide/CoCl2 catalyst reaction mixture, only biphenyl was formed. A re markable reaction! smost likely a free radical process, as Kharasch suggested. The organic halide was believed to function as an oxidizing agent. This interesting, simple, and potentially useful cross-coupling reaction, as exempli? ed in eq 4, was not adopted by the synthetic organic community right away. After a long dormancy it was rediscovered some 30 years later by a number of groups in the USA, Japan, and France, all of whom apparently were not aware of the 1943 Kharasch/Fuchs JACS paper. 1 Transition-metal catalysts other than CoCl2 were used, but the concept and the basic reaction were the same. In 1971 Tamura and Kochi reported a thorough study of the cross-coupling of Grignard reagents with vinylic halides catalyzed by soluble iron species in concentrations of ca. 10-4 M in THF at 0-25  °C. 26,27 Various Fe(III) compounds could be used as Fe catalyst precursors; the best were Fe(III) -diketonates such as Fe(RC(O)CHC(O)R)3 (R ) Ph, CH3, t-Bu). These exothermic reactions we re not free radical processes. The reactions of cis- and trans-propenyl bromide proceeded with retention of geometric con? uration (eqs 6 and 7) and were not adversely affected by the presence of 0. 4 M styrene. A ArMgBr + RCHdCHX 9 ArCHdCHR + MgBrX 8 (X ) Cl, Br) CoCl2 5 mol % (4) 2ArMgX + MXn f Ar-Ar + MgX2 + MXn-2 (5) A novel catalytic process for such ArMgX to Ar-Ar coupling was discovered by Kharasch and Fields when ethereal solutions of an aryl Grignard reagent that contained a catalytic amount (3 mol %) of CoCl2 were heated at re? ux for 1 h and then treated with an equivalent amount of an organic halide (C6H5Br, C2H5Br, i-C3H7Cl). 20 The coupling reaction to give Ar-Ar did (15) (a) Bott, L.L. Hydrocarbon Process. Petrol. Re? ner 1965, 44, 115. (b) Guccione, E. Chem. Eng. 1965, (June 21), 102. See also Part 2 of the tetraethyllead essay: (c) Seyferth, D. Organometallics 2003, 22, 5154 (pages 5172-5174). (16) (a) Krause, E. ; von Grosse, A. Die Chemie der metall-organischen Ve rbindungen; Gebruder Borntrager: Berlin, 1937; pp 14-61, 110-114. ? ? (b) Kharasch, M. S. ; Reinmuth, O. Grignard Reactions of Nonmetallic Substances; Prentice Hall: New York, 1954. (c) Handbook of Grignard Reagents; Silverman, G. S. , Rakita, P. E. , Eds. ; Dekker: New York, 1996. d) Grignard Reagents-New DeVelopments; Richey, H. G. , Ed. ; Wiley: Chichester, New York, 2000. (e) The Chemistry of Organomagnesium Compounds; Rappaport, Z. , Marek, L. , Eds. ; Wiley-VCH: Weinheim, Germany, 2008. (17) Knochel, P. ; Dohle, W. ; Gommermann, N. ; Kneisel, F. F. ; Kopp, F. ; Korn, T. ; Sapountzis, J. ; Vu, V. A. Angew. Chem. , Int. Ed. 2003, 42, 4302 (review). (18) Kharasch, M. S. ; Fuchs, C. F. J. Am. Chem. Soc. 1943, 65, 504. (19) Gilman, H. ; Lichtenwalter, M. J. Am. Chem. Soc. 1939, 61, 957. and earlier (back to 1914) references cited therein. 20) Kharasch, M. S. ; Fields, E. K. J. Am. Chem. Soc. 1941, 63, 2316. mechanism involving an organoiron(I) intermediate, obtained by reduction of the Fe(III) precursor by the Grignard reagent, was suggested. The results of a few experiments carried out on a 30-40 mmol scale (Table 3) showed that such iron-catalyzed reactions would be useful in the synthesis of ole? ns, but a broader study to optimize them and to broaden the scope of their application was not undertaken. The coupling of vinylic Grignard reagents with alkyl halides is catalyzed also by Ag(I) salts. 8 Thus, cis-propenylmagnesium (21) Two later â€Å"historical notes†22,23 and two book chapters24,25 that dealt with the cross-coupling reactions of Grignard reagents with vinylic halides also did not cite the Kharasch/Fuchs paper. (22) Tamao, K. J. Organomet. Chem. 2002, 653, 27. (23) Murahashi, S. -I. J. Organomet. Chem. 2002, 653, 27. (24) Kochi, J. K. Organometallic Mechanisms and Catalysis; Academic Press: New York, 1978; Chapter 14, Sections III and IV. (25) Hou, S. ; Negishi, E. -i. In Handbook of Organopalladium Chemistry; Negishi, E. -i. , Ed. , Wile y: New York, 2002; Vol. 1,Chapter III. 2. 6, pp 335408.As a historical note, the following quotation from this reference (p 335) is of interest: â€Å"Although the reaction of Grignard reagents with organic halides was shown to be catalyzed by various late transition metal compounds (the Kharasch reaction) in the 1950s, it was not until the early 1970s that the applicability of this catalytic method was extended to the cross-coupling involving alkenyl and aryl halides catalyzed by Ag, Fe and other late transition metals. † (26) (a) Kochi, J. ; Tamura, M. J. Am. Chem. Soc. 1971, 93, 1487. (b) Tamura, M. ; Kochi, J. Synthesis, 1971, 303. (27) Full papers: (a) Neumann, S.M. ; Kochi, J. K. J. Org. Chem. 1975, 40, 599. (b) Smith, R. S. ; Kochi, J. K. J. Org. Chem. 1976, 41, 502. (c) Reviews: ref 24. (d) Kochi, J. K. J. Organomet. Chem. 2002, 653, 11 (historical note). (28) (a) Whitesides, G. M. ; Casey, C. P. J. Am. Chem. Soc. 1966, 88, 4541. (b) Tamura, M. ; Kochi, J. J. Am. Chem . Soc. 1971, 93, 1483. 1602 Organometallics, Vol. 28, No. 6, 2009 Table 3. Alkenylation of Grignard Reagents using FeCl3 as Precatalyst (in THF)a R MgBr (amt, mmol) n-C6H13MgBr (40) CH2dCH(CH2)4MgBr (36) n-C6H13MgBr (40) a 1 R2Br (amt, mmol) CH2dCHBr (204) CH2dCHBr (102) CH3CHdCHBr (355)FeCl3 (amt, mmol) 0. 05 0. 05 0. 10 reacn temp,  °C 0 25 25 product (yield, %) n-C6H13CHdCH2 (83) CH2dCH(CH2)4CHdCH2 (64) n-C6H13CHdCHCH3 (67) (53/47 cis/trans mixture) Taken from: Synthesis 1971, 6, 303. Scheme 2 bromide reacted with methyl bromide in THF in the presence of an Ag(I) catalyst to give cis-butene-2, but a similar reaction of trans-propenylmagnesium bromide gave a 7:3 mixture of cisand trans-butene-2, respectively. 28b Apparently propenyl radicals were involved. A similar Grignard reagent based cross-coupling, ole? n synthesis in which a copper(I) catalyst was used was published by French workers. 9 Normant et al. reported that their reactions (e. g. , n-Bu(Et)CdCHI + i-PrMgCl in THF at -20  °C with a Cu(I) catalyst) proceeded with retention of con? guration. 29a For a reaction of CH3CHdC(CH3)MgCl with n-C3H7I in THF at 0  °C using CuI as catalyst, Linstrumelle reported that the coupling product obtained in 97% yield was 88% cis and 12% trans, while a similar reaction of CH2dC(CH3)MgBr with trans-n-C6H13CHdCHI gave a 4:1 trans/cis product. 29b TheuseofNi(II)catalystprecursorsforGrignardreagent-vinylic halide cross-coupling was reported in 1972 by Corriu and Masse30 and by Tamao, Sumitani, and Kumada. 1 The French group found Ni(II) acetylacetonate to be the most effective catalyst precursor, while the Japanese group favored a bis(tertiary phosphine)NiCl2 catalyst precursor and, especially, chelating diphosphine complexes such as (Ph2PCH2CH2PPh2)NiCl2. Reactions carried out in diethyl ether at re? ux generally gave excellent yields. This procedure has been carried out commercially on an industrial scale in the preparation of p-chloroand p-tert-butylstyrene. 3 2 Finally, the last to be discovered at that time and the most versatile procedure for the cross-coupling of Grignard reagents (29) (a) Normant, J. F. Commercon, A. ; Cahiez, G. ; Villieras, J. Compt. ? rend. Hebd. Seances Acad. Sci. , Ser. C 1974, 278, 967. (b) Derguini? Boumechal, F. ; Linstrumelle, G. Tetrahedron Lett. 1976, 3225. (30) Corriu, R. J. P. ; Masse, J. P. J. Chem. Soc. , Chem. Commun. 1972, 144. (31) (a) Tamao, K. ; Sumitani, K. ; Kumada, M. J. Am. Chem. Soc. 1972, 94, 1375. (b) See also ref 22. Later work: (c) Tamao, K. ; Kiso, Y. ; Sumitani, K. ; Kumada, M. J. Am. Chem. Soc. 1972, 94, 9268. (d) Kiso, Y. ; Tamao, K. ; Kumada, M. J. Organomet. Chem. 1973, 50, C12. (e) Kiso, Y. ; Tamao, K. ; Miyake, N. ; Yamamoto, K. ; Kumada, M. Tetrahedron Lett. 974, (No. 1), 3. (f) Tamao, K. ; Sumitani, K. ; Kiso, Y. ; Zembayashi, M. ; Fujioka, A. ; Kodama, S. ; Nakajima, I. ; Minato, A. ; Kumada, M. Bull. Chem. Soc. Jpn. 1976, 49, 1958. (g) Tamao, K. ; Kodama, S. ; Nakajima, I. ; K umada, M. ; Minato, A. ; Suzuki, K. Tetrahedron 1982, 38, 3347. (32) Banno, T. ; Hayakawa; Umeno, M. J. Organomet. Chem. 2002, 653, 288. (33) (a) Yamamura, M. ; Moritani, I. ; Murahashi, S. -I. J. Organomet. Chem. 1975, 91, C39. Full paper: (b) Murahashi, S. -I. ; Yamamura, M. ; Yanagisawa, K. -i. ; Mita, N. ; Kondo, K. J. Org. Chem. 1979, 44, 2408. (c) Historical note: ref 23. ith vinylic and aryl halides, that catalyzed by palladium complexes, was reported by Shun-Ichi Murahashi and coworkers in 1975. 33a The reactions were carried out in diethyl ether/benzene at room temperature using (Ph3P)4Pd as the catalyst precursor, and they proceeded stereospeci? cally in excellent yield (Scheme 2). Dang and Linstrumelle also used this procedure to prepare 1,3-dienes stereospeci? cally by the reaction of vinylic iodides with vinylic Grignard reagents. 34 Palladium-catalyzed cross-coupling of Grignard reagents with organic halides has been a very active area in organic synthesis.Reference 25 reviews (up to 2002) its application in (alkenyl) MgX-ArX, ArMgX-(alkenyl)X, and (alkenyl)MgX-(alkenyl)X coupling processes. A further chapter in this book deals with ArMgX-Ar? X coupling. 35 Another surge of research activity on cross-coupling of Grignard reagents with organic halides started around the turn of the century and still appears to be in progress at the present time (January 2009). Interest has revived in the use of iron complexes as precatalysts for the cross- and homocoupling of Grignard reagents,36 since iron complexes are cheaper than those of palladium and are nontoxic.The iron-catalyzed cross-coupling of organomagnesium bromides with vinylic bromides, although it produced ole? ns in good yield, was of interest to Jay Kochi, as noted above, primarily from the point of view of its reaction mechanism rather than of its potential for application in organic synthesis. After some 25 years several research groups carried out much experimental work which has shown iron-c atalyzed cross-coupling and homocoupling of Grignard reagents to be broadly applicable and very useful additions to the methods of organic synthesis.In 1995 Gerard Cahiez, at the Universite Pierre et Marie Curie ? ? in Paris, during the course of his extensive investigations of organomanganese chemistry, found that the cross-coupling of vinylic bromides with alkyl, vinylic, and phenylmanganese chlorides could be effected in good yield in the presence of 3 mol % of iron(III) acetylacetonate in a THF/N-methyl-2pyrrolidinone (NMP) mixed solvent at room temperature. 37 In a thorough study, this reaction was extended to the crosscoupling of vinylic halides with alkylmagnesium halides using 1 mol % of Fe(acac)3 and the same solvent mixture. 8 High yields of ole? nic products were obtained. Successful crosscoupling of Grignard reagents with AcO(CH2)6CHdCHCl, CH3C(O)(CH2)3CHdCHCl, Cl(CH2)4CBrdCH2, 9, and 10 are noteworthy as examples of the selectivity and functional group tolerance of this reaction. The scope of this chemistry was extended further when some of Knochel’s functionally substituted aryl Grignard reagents17 (vide supra) were reacted with vinylic bromides and iodides. 39 The cross-coupling reaction between aryl Grignard reagents and vinylic bromides and iodides also was found by Cahiez and co-workers to give ole? ic products in good yield with Organometallics, Vol. 28, No. 6, 2009 1603 Table 4. Iron-Catalyzed Biaryl Coupling Reactions a Table 5. Iron-Catalyzed Homocoupling of Grignard Reagents with Atmospheric Oxygen as Oxidanta a Taken from: J. Am. Chem. Soc. 2007, 129, 13788. palladium or nickel precatalysts. 42 Of these procedures, that of Cahiez et al. 41f appears to be the most useful. Alkyl halide/ alkylmagnesium halide cross-coupling is not a practical process. 43 RMgX + R? X 9 R-R? + MgX2 8 [Fe] (8)Iron-catalyzed reactions of aryl Grignard reagents with aryl halides to give biaryls generally are not synthetically useful. The desired cross-co upling products are obtained in only poor yield, the main product being the homocoupled biaryl derived from the aryl Grignard reagent (eq 9) (recall the Gilman/ Lichtenwalter and Kharasch/Fields reactions, vide supra). ArMgX + Ar? X f Ar-Ar? + (low yield) (major Ar-Ar product) (9) a Taken from: J. Am. Chem. Soc. 2007, 129, 9844. retention of geometric con? guration when carried out in THF solution in the presence of 10 mol % of MnCl2. 0 As noted above, Kharasch and Fuchs had found that attempts to cross-couple aryl Grignard reagents with alkyl halides in the presence of catalytic amounts of CoCl2 were unsuccessful. On the other hand, such reactions do occur in the presence of an iron precatalyst and various additives (eq 8, R? ) alkyl), as summarized in ref 36. A number of other groups have reported the results of their research directed toward development of an effective procedure for the process shown in eq 8, all using an iron precatalyst of one kind or another, various additives such as TMEDA, NMP, etc. nd generally diethyl ether (but sometimes THF) as solvent. 41 It is noteworthy that primary and secondary alkyl halides, i. e. , ones that contain hydrogen substituents on the carbon atom, can be cross-coupled with aryl Grignard reagents, a process that cannot be realized using (34) Dang, H. P. ; Linstrumelle, G. Tetrahedron Lett. 1978, 191. (35) Anastasia, L. ; Negishi, E. -i. Chapter II. 2. 5, pp 311-344, in ref 25. (To date palladium and nickel catalysts have been widely used to effect aryl-aryl cross-coupling reactions. However, arylmagnesium halides were found to undergo cross-coupling with aryl halides that contain electron-withdrawing activating substituents ortho or para with respect to the halogen substituent in the presence of 10 mol % of manganese(II) chloride (eq 10). 44 Cyclohexyl and 2-methylpropenyl Grignard reagents reacted with such substituted halobenzenes in a similar manner. Very (36) (a) Cahiez, G. ; Duplais, C. â€Å"Iron-Catalyzed Re actions of Grignard Reagents†, Chapter 13, pp 594-630 in ref 16e. (b) Furstner, A. ; Leitner, ? A. ; Mendez, M. ; Kraus, H. J. Am.Chem. Soc. 2002, 124, 13856 (a long ? paper that brings an excellent discussion of the literature, of questions concerning mechanism, and original results). (c) Sherry, B. D. ; Furstner, ? A. Acc. Chem. Res. 2008, 41, 1500. (37) Cahiez, G. ; Marquis, S. Tetrahedron Lett. 1996, 37, 1773. (38) Cahiez, G. ; Avedissian, H. Synthesis 1998, 1199. (39) Dohle, W. ; Kopp, F. ; Cahiez, G. ; Knochel, P. Synlett 2001, 1901. 1604 Organometallics, Vol. 28, No. 6, 2009 Table 6. Manganese-Catalyzed Homocoupling of Grignard Reagents with Atmospheric Oxygen as Oxidanta Scheme 4THF to a mixture of 3 mol % of FeF3  · 3H2O and 9 mol % of an N-heterocyclic carbene (SIPr  · HCl). In one example, chlorobenzene (1. 0 equiv) and p-CH3C6H4MgBr (1. 2 equiv) were added to this catalyst system and the reaction mixture was stirred at 60  °C for 1 day. The desired product, p -CH3C6H4-C6H5, was obtained in 98% yield. The homocoupling product, biphenyl, was present only in trace amount, while CH3C6H4C6H4CH3 was formed in 3% yield. Some examples of the application of this remarkable reaction are shown in Table 4. Good results were obtained only with aryl chlorides.Aryl bromides and iodides gave low biaryl yields. A German group reported similar MnCl2-catalyzed cross-coupling between various heterocyclic chlorides and aryl as well as alkyl Grignard reagents: e. g. , eq 11. 46 a Taken from: J. Am. Chem. Soc. 2007, 129, 13788. The homocoupling reaction of aryl Grignard reagents, mentioned earlier, also has received renewed attention recently, and synthetically useful procedures have resulted. Nagano and Hayashi developed a procedure in which the reaction is carried out in re? uxing diethyl ether in the presence of 1-5 mol % of FeCl3, NMP and 1. molar equiv of 1,2-dichloroethane (which serves as the oxidant). 47 Cahiez and co-workers have improved this procedu re by using THF as solvent, in which arylmagnesium halides, including the chlorides, are more easily prepared. 48 This procedure works well with Knochel’s functional arylmagnesium halides (Scheme 3). Of interest also is the clever construction of the tricyclic system 11 by intramolecular homocoupling (Scheme 4). (40) (a) Cahiez, G. ; Gager, O. ; Lecomte, F. Org. Lett. 2008, 10, 5255. (b) Alami, M. ; Ramiandrasoa, P. ; Cahiez, G. Synlett 1998, 325. 41) A selection: (a) Martin, R. ; Furstner, A. Angew. Chem. , Int. Ed. ? 2004, 43, 3955 (see also ref 36b and references cited therein). (b) Nagano, T. ; Hayashi, T. Org. Lett. 2004, 6, 1297. (c) Bedford, R. B. ; Bruce, D. W. ; Frost, R. M. ; Goodby, J. W. ; Hird, M. Chem. Commun. 2004, 2822. (d) Nakamura, N. ; Matsuo, K. ; Ito, S. ; Nakamura, E. J. Am. Chem. Soc. 2004, 126, 3686. (e) Bedford, R. B. ; Bruce, D. W. ; Frost, R. M. ; Hird, M. Chem. Commun. 2005, 4161. (f) Cahiez, G. ; Habiak, V. ; Duplais, C. ; Moyeux, A. Angew. Chem. , Int. Ed. 2007, 46, 4364. g) Cahiez, G. ; Duplais, C. ; Moyeux, A. Org. Lett. 2007, 9, 3253. (h) Guerinot, A. ; Reymond, S. ; Cossy, J. Angew. ? Chem. , Int. Ed. 2007, 46, 6521. (42) However, Terao and Kambe have recently developed new Pd- and Ni-based precatalyst systems which avoid the problem of -elimination of primary and secondary alkyl groups: Terao, J. ; Kambe, M. Acc. Chem. Res. 2008, 41, 1545. (43) (a) Tamura, M. ; Kochi, J. J. Organomet. Chem. 1971, 31, 289. (b) Rollick, K. L. ; Nugent, W. A. ; Kochi, J. K. J. Organomet. Chem. 1982, 225, 279. (44) Cahiez, G. ; Lepifre, F. Ramiandrasoa, P. Synthesis 1999, 2138. (45) Hatakeyama, T. ; Nakamura, M. J. Am. Chem. Soc. 2007, 129, 9844. (46) Rueping, M. ; Ieawsuwan, W. Synlett 2007, 247. (47) Nagano, T. ; Hiyama, T. Org. Lett. 2005, 7, 491. (48) Cahiez, G. ; Chaboche, C. ; Mahuteau-Betzer, F. Org. Lett. 2005, 7, 1943. Scheme 3 special, but generally applicable, reaction conditions developed by Japanese workers45 have ? nally prov ided the possibility of clean aryl-aryl cross-coupling reactions in which competitive homocoupling of the aryl Grignard reagent has been almost completely suppressed.In this procedure an active catalyst system was prepared by addition of 18 mol % of C2H5MgBr in Organometallics, Vol. 28, No. 6, 2009 1605 A further improvement resulted when it was found that atmospheric oxygen could replace the 1,2-dihaloethane as oxidant in the homocoupling of aryl, vinylic, and alkynyl Grignard reagents using either Fe or Mn catalyst precursors. 49 As Tables 5 and 6 show, this procedure gave excellent results. The most recent contribution to iron-catalyzed cross-coupling, which appeared during the preparation of the ? al draft of this paper, involves application of the old one-pot Barbier procedure in which FeCl3 served as precatalyst and stoichiometric amounts of magnesium turnings and TMEDA additive were used. A mixture of an alkyl and an aryl bromide was added to the mixture of precatalyst, TMEDA , magnesium, and solvent at 0  °C. Good yields of cross-coupled products were obtained. 50 There has been a great deal of activity in the areas of Grignard reagent/organic halide cross-coupling and aryl Grignard reagent homocoupling, and the coverage in this essay, whose focus is on the historical aspects, is far from exhaustive.Attention is called to the 2005 review by Frisch and Beller51 and especially (49) Cahiez, G. ; Moyeux, A. ; Buendia, J. ; Duplais, C. J. Am. Chem. Soc. 2007, 129, 13789. (50) Czaplik, W. M. ; Mayer, M. ; von Wangelin, A. J. Angew. Chem. , Int. Ed. 2009, 48, 607. (51) Frisch, A. C. ; Beller, M. Angew. Chem. , Int. Ed. 2005, 44, 674. to the recent Accounts of Chemical Research special issue on cross-coupling. 52 Since ? st reported in 1943, the cross-coupling of Grignard reagents with organic halides, thanks to further development by many later workers, has become a broadly applicable, very useful reaction in organic synthesis. There is much more about Grign ard reagents that I have not covered: the various procedures used in their preparation, the mechanism of their formation (which is still controversial), the more complex organomagnesium compounds such as bis(cyclopentadienyl)magnesium, magnesium butadiene, and magnesium anthracene, and the many kinds of reactions that Grignard reagents have been reported to undergo.But this is only a short essay, and so I have been able to cover only a few selected topics, ones which I hope will be of interest to the reader. More information can be found in the books that I have cited earlier. 16 Acknowledgment. My thanks, as always, to Professor Arnold L. Rheingold for the cover ? gure. OM900088Z (52) Acc. Chem. Res. 2008, 41, No. 11, 1439-1564, special issue. A collection of 11 reviews, many of them relevant to the subject matter of the present essay, with useful, up-to-date references.

Causes of Road Accidents in Malaysia Essay

The Causes Of Road Accidents In Malaysia Time to time, half a million of Malaysians died because of road accidents and the highest cases of road accidents are caused by the drivers’ behaviour, equipment failure and the road conditions and infrastructure. Because of the road accidents many people have lose their family member or close friend. Besides, the road accidents also may effected to government when they have to repair for the broken infrastructure that caused by the accident like lamp stand, road divider, cleaning people blood from the road, and many more.It also will give a traffic jam for a while to all drivers. According to Road Transport department research (2002)Accident casualty and deaths by vehicles for Malaysia 2000-2006, the number of road accidents increased to 400 cases and it decreased in 2006 that was only about 600 cases (21,600 cases) had been reported. The first thing that contributes to the reason for the road accidents that happen in Malaysia is the d rivers’ behaviour. Humans are always do mistake and not careful. When a problem or unwanted thing happens, they tend to blame somebody or something else for what they have done.Most people that get an accident believe the other party involved could have done something different to avoid the accident. According to The Royal Malaysian Police, PDRM (2006) report saying that 90% of accidents happen from this reason. Moreover they also mentioned that speeding also has caused quite a number of accidents. Actually, until recently many drivers, especially male driver took the chance of night time in driving in federation and state roads. PDRM, (2006) reported the faster speed of a vehicle, the greater the risk of an accident.Speeding, even if the vehicle going five miles per hour over, in the wrong place at the wrong time, it can bring death to somebody. Speeding is also based on the traffic on an area, road conditions, weather and lighting. When driver speeding, they had to risk the ir lives when had to alert about what condition will they face. Despite all major highways have speed trap, it still cannot prevent drivers to speed and get into trouble, such an accident. In addition, careless driver are another drivers’ behaviour that caused the road accidents.This factor is the highest factors that drivers get involved in road accidents. Some drivers not only speeding but also drive recklessly, breaking road rules, does not have their vehicle license and beating traffic lights. Moreover, drivers either man or women cannot prevent to be careless driver. The main cause that driver become un careful while driving on roads are talking on a cell phone, eating, falling asleep, tiredness, driving under the influence of alcohol and so on. Because of the small mistake can caused a big problem to others who using the road o involved in the accidents.However, the most important cause of an accident is aggressive driver behaviour and selfish attitudes. From e-how, des cribed, safe standards are manufactured for modern cars by engineer to minimize the effect of accident. The aggressive driver behaviour and selfish attitudes are the most impossible thing to change. The examples of aggressive driver behaviour and selfish attitudes are aggressive tailgating, failure to signal, and failure to use the right way side. Aggressive tailgating happen when you follow in front of other vehicle too close.With two vehicle drive too close in high speed, there will be a huge accident if unexpected thing happen on the road, such as animal crossing the road and required front vehicle stop immediately or evade from being crush into the animal. Furthermore, failure to signal when taking left or right road at the corner of the road. When this happen, other vehicle does not know which way you want to go either left or right. Especially heavy vehicles, they do not see where you want to turn if you does not turn on the signal light from your vehicle.There also a lot of p roblem happen if driver do not use the right way side, it will make other driver mad. When they angry, they will flash light at the back of your vehicle, because of you drive to slow also in wrong way side of the road. Other example is every festive season, like Chinese New Year, Hari Raya Aidilftri ,Deepavali, Christmas including New Years, Malaysians especially, always excited of going back to their village or better known as ‘balik kampung’. With the excited feeling of going back to their home towns, we can see many of them and their family trying their best to reach home quickly as they can.Thus they will become selfish and does not care about their safety. Some of them will take express bus to arrive at their home to avoid driving a car at night. But they will be unlucky if they get selfish and careless driver bus attitudes that always take the wrong side of the road which should not used by heavy vehicle just want to reach the destination early. The most the endan ger transportation is heavy vehicle like bus and lorry because they are big and easy to smash small vehicle.Other than that, many selfish motorcyclists who did not followed traffic rules and fastened safety helmets properly. Another factor that listed as one of the causes of road accident is equipment failure of a vehicle. From smartmotorist. com, it state that the most important types of equipment failure are loss of brkes, tire blow outs or tread separation, and suspension failure. Thus, with all exception of the recent rash of Firestone light-truck tire failures, calculated the totals that less than 5% of all motorvehicle accidents have reported equipment failure accounts.All drivers should drive with perfect car condition. So, before drive any vehicle, they have to do some conformation. They need to check their vehicle to make sure if it safe to drive or not. As example, they must check the condition of water, brake, battery and lamp always be in good condition. There are some d rivers that never take care of this problem. They feel it is a small matter to think about the problem and can do it later at any time. They do not care about the safety factor of their car.Such as they do not change the worn out tires, when it was worn out, the vehicle absolutely cannot grasp tightly the road surface perfectly. So, it will be more dangerous if in rainy day situation, it because the stranglehold between tires and road surface will be more weak than sunny day condition. There are so clear that worn out tires can caused the accident easily. Besides, there are many people cannot accept a fact that almost nine million vehicle in this country involved in road accident because the using of illegal equipment which gain the worst level.The amount of that vehicle is about 80 percent from the 11 million of the vehicle in our country. The president of Persatuan Pemilik kenderaan Bermotor Malaysia (MOVA), Ahmad Zaki Arifin said that more than half from the driver in our country face the risk to involved in accident and death about this behaviour. Although, the other reason that caused the accident is the road conditions and infrastructure. Usually, the road will become danger in rainy day. It will make the road become more slippery for the vehicle to handle.In addition, many potholes could endanger motorist (Road Transport Department, 2002). It because, deep hole can make motorist cannot control their vehicle and will cause the accident. It become worst if it involved with the motorcyclist. The un flat surface of road also can make a nightmare for road user. It because, the road user cannot see the hole while driving. Most accidents that involved pothole problem happen during night time, because at that time many driver could not recognize the hole when they driving.Other than that, insufficient and improper of street light, also caused the accident. Usually, The street lights are hard to find in village area. So, the authorities should take care the vill age area too. In some place, the street light cannot be used by people because the street light is already broken and not repaired by authorities. In other case, the insufficient of traffic light also lead us to road accident, interstate highways remain safest road because their flow of traffic is in one direction and complete with traffic light.Many case of accident caused by insufficient of traffic light such as there are no traffic light at one road that always full with vehicle and the effect is it will produce a huge traffic jam. It will become worst when some drivers do not think about other road user and drive in high speed when taking a corner or change to the other side of road. However, roadway identifications sign also play the role to make the road safe for road user. It useful to inform road user to locate and know the road condition, such as the location of landslide, school location, hospital and many more.If the driver was informed properly the accident will not happ en easily. It is possible that motorcyclist also need specific lane for them. They should be separate from other ‘big’ user like car, lorry, bus and other type of transport that bigger than motorcycle. It will make them more safe and secure from unwanted accident. In conclusion, driver behaviour and the equipment failure of a vehicle, as well as the road conditions and infrastructure seem to be causes of road accidents in Malaysia.To reduce the total amount of road accident, first thing that should we do are change our attitude. In addition, we also need to be alert about our vehicle condition and always check them. The rate of road accident in our country today has become a nightmare for all of us. So, the authorities may need to do a drastic step to overcome this worst problem. They need to use their power to serve the best road conditions and infrastructure for us. We need to realize that our live is most valuable thing. ‘Drive safety and safe our soul’.

7 More Fixes for Dangling Modifiers

7 More Fixes for Dangling Modifiers 7 More Fixes for Dangling Modifiers 7 More Fixes for Dangling Modifiers By Mark Nichol Some time ago, I pointed out the perils of dangling modifiers, presenting sample sentences and offering annotated revisions. Unfortunately, my stock of such specimens, discovered in the course of my editing work and in leisure reading alike, has grown rather than diminished. I therefore here inflict another set of them on you, one of as many rounds as are necessary to finally eradicate dangling modifiers from the face of the Earth. As a guest columnist for DailyWritingTips explained quite well in her post on the topic, â€Å"The dangling modifier is usually a phrase or an elliptical clause (a dependent clause in which some words have intentionally been left out), often at the beginning of a sentence, that either doesn’t modify anything specific in the sentence or modifies the wrong word or part of the sentence.† Here’s a dissection of sentences entangled by dangling modifiers: 1. â€Å"Drawn from a series of wildly popular cookbooks, international culinary celebrity, Australia-based Steve James, presents practical versions of the world’s greatest vegetarian cuisine.† The sentence implies that the celebrity in question is drawn from the cookbooks. Whenever you’re confronted with such a contextual contortion, start with the subject. While you’re at it, level the adjectival stack by relaxing the person’s description: â€Å"Steve James, an international culinary celebrity based in Australia, presents practical versions of the world’s greatest vegetarian cuisine drawn from a series of wildly popular cookbooks.† 2. â€Å"Once used to store ice, food, and alcohol, guests can still explore the mine and enjoy its cool temperature all year round.† Guests can consume ice, food, and alcohol, but they can’t store it. That’s the mine’s job, so recast the sentence to say as much by, as in the previous example, simply starting with the subject, followed by the reference to its earlier purpose: â€Å"The mine was once used to store ice, food, and alcohol, and guests can still explore the tunnels and enjoy their cool temperature all year round.† 3. â€Å"Originally founded as a purveyor of trinkets for Japanese festivals and carnivals, the company’s rise to prominence began in the early 1970s.† The use of a possessive form of a noun immediately after an introductory modifier is a screaming sign of a syntactical screw-up. The subject of the sentence is not â€Å"the company,† but â€Å"the company’s rise to prominence,† so it is the company’s rocket to stardom, not the company itself, that is incorrectly being identified as having been founded. Recast the sentence so that the company itself, not its ascendancy, is the subject: â€Å"The company, originally founded as a purveyor of trinkets for Japanese festivals and carnivals, rose to prominence beginning in the early 1970s.† 4. â€Å"As your mortgage loan originator, you will receive the benefit of my lending experience and ongoing education to help guide you throughout the entire loan process.† I’ve heard of self-service, but this is ridiculous. This sentence seems to be confused about the identity of my mortgage loan originator, who (in this case, anyway), inappropriately puts the customer first. The writer is offering their expertise, so the subject must be a first-person pronoun: â€Å"As your mortgage loan originator, I offer you the benefit of my lending experience and ongoing education to help guide you throughout the entire loan process.† 5. â€Å"While going to the bar one last time, my ‘Mike Johnson’ campaign sign accidentally falls out of my jacket pocket.† The writer’s â€Å"Mike Johnson† campaign sign has obviously gone to the bar too many times already if it can’t prevent itself from falling out of his jacket pocket. The writer must introduce themselves into the modifier to make it clear that they, not the sign, are frequenting the bar: â€Å"While I’m going to the bar one last time, my ‘Mike Johnson’ campaign sign accidentally falls out of my jacket pocket.† (Also, the quotation marks around the candidate’s name are optional, but because those words are presumably featured on the sign, the marks are appropriate.) 6. â€Å"Bordered by Libya, Sudan, Niger, Nigeria, Cameroon, and the Central African Republic, the CIA list for natural hazards includes ‘periodic droughts and locust plagues,’ which places Chad in a proper biblical context.† Chad, not the CIA list, is bordered by the other named nations, so why is it relegated to the end of the sentence? Introduce it, appropriately, in the introductory phrase: â€Å"The list of natural hazards for Chad, bordered by Cameroon, the Central African Republic, Libya, Niger, Nigeria, and Sudan, includes ‘periodic droughts and locust plagues,’ which places the nation in a proper biblical context.† (Notice, also, that I reordered the heretofore randomly listed names of countries alphabetically; for geographical entities, a sequence corresponding to relative location is also appropriate. Avoid arbitrarily ordered lists.) 7. â€Å"Since releasing their 2002 debut, the biggest criticism directed at the band has been that they couldn’t replicate their raucous live energy in the studio.† Is â€Å"the Biggest Criticism† the name of the band? No. The unnamed band released the debut, so the sentence must be heavily revised to shift â€Å"the band† to immediately follow the introductory modifier: â€Å"Since the release of their 2002 debut, the band has been the subject of criticism, primarily that it couldn’t replicate its raucous live energy in the studio.† (Also in American English, at least a band is a single entity and should be referred to by single pronouns.) Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Grammar category, check our popular posts, or choose a related post below:20 Types and Forms of HumorLatin Plural EndingsThe Difference Between "Shade" and "Shadow"

A Comparison of Freud and Fromm essays

A Comparison of Freud and Fromm essays Sigmund Freud was born in Monrovia on May 6,1856. He entered the University of Vienna in 1873 at the age of 17. He finished his degree in 1881. Freud died in England in 1939. He was an active therapist, theorist and writer to the very end. ( Ewen 19-20) Erich Fromm was born four years after Freud in 1900 in Frankfurt, Germany. Unlike Freud, Fromm had no medical training in his background. He received his PHD from the University of Heidelberg and later studied at Berlin Psychoanalytic Institute. Erich Fromm died March 16, 1980 in Switzerland. (Ewen 187) While Freud and Fromm were contemporaries and shared some basic beliefs, their approach to most issues varied greatly. Freuds attitude was purely scientific. Fromm desired to humanize things. Fromm accepted the importance of unconscious, biological drives, repression and defense mechanisms, but rejected Freuds theory of id, ego and superego. Fromm did not believe in specific developmental stages. He believed that the growing child slowly learns to distinguish between I and not I, through contact with the environment, notably those involving the parents.(Ewen 194) Fromm contends that personality development continues into adulthood. He believes that if a child keeps up with the increasing feelings of isolation, that anxiety can be kept to a minimal and personality development proceeds normally. Freuds well-known theory is that the personality is determined during the first five years of life. He believes we proceed through a series of psychosexual stages: oral, anal, urethral, phallic, a latency period and genital. Freud contends that the genital stage is the goal of normal development and that it represents true maturity. ( Hansen 25-26) Fromm warns against pathogenic behavior because it can damage the childs sense of reliance. He believed healthy pers...