有机合成入门教材-How to Tackle Organic Syntheses？ word格式，共34页，部分内容如下： http://orac.sunderland.ac.uk/~hs0bcl/org1.htm how to tackle organic syntheses - a beginner's guide by prof otto meth-coh n introduction does the following . . . . . . make you want to become a nun or a monk? if so, take heart! by the time you have worked through this little weblet (the web equivalent of a booklet) you'll be surprisingly good at this vital art. why is synthesis so important anyway, you might well ask. i reckon it is one of the most important things that make the uk still able to compete in the tough business world of today. britain is uniquely good at organic synthesis. it is the most important contribution to our positive balance-of-payments. or, in other words, it is the most important area of work in the uk today. if you end up in the pharmaceutical industry, then you'll be part of a team making drugs - that's synthesis! but anything that is so important isn't necessarily easy - so this weblet is to give you the unfair advantage over others - to make you a good synthesiser! so where do we start? if we think of synthesising as being like building then first you need a toolkit with some tools in it. that's the point of part 1. then you need a little practice - part 2. but first you need to understand a few simple ideas. if you haven't been a builder before - where do we start??? with the foundations - and that's where we start but in synthesis we then do an odd thing - we work backwards............................!!! synthesis is considered difficult because you need to have a grasp of lots of reactions. well i want to show you that if you have an understanding of simple basic organic chemistry plus a few special 'tools' that i'll equip you with, you can do a surprising amount - and enjoy the challenge! synthesis is mostly to do with making c-c bonds and then adjusting a functional group or two. so the key thing to learn is how best to make c-c bonds. the most important methods for making c-c bonds that we will focus on all involve using carbanions which, not surprisingly, react with electron-poor reagents electrophiles so here goes with filling your toolkit..........the first reaction involves the amazing organo-magnesium derivatives - the grignard reaction. the grignard reaction victor grignard was an enthusiastic young french chemist who discovered how to make organomagnesium halides (rmgx) while working for his ph.d. his boss, barbier, had been trying this sort of chemistry for some time, but victor was the genius who solved the problem. this discovery in 1901 changed the course of organic chemistry and won him the nobel prize in 1912. we now refer to such compounds as grignard reagents - and they are the first tool in your bag. victor's breakthrough came with two discoveries - an ether solvent was vital and the whole chemistry must be carried out bone dry . you take an alkyl halide (preferably a bromide or iodide but a very reactive chloride such as tertiary-butyl chloride or benzyl chloride will be ok) magnesium metal and ether (dried with sodium metal) and with a little persuasion you get a vigorous reaction resulting in a grignard reagent. the reagent is used in solution (it is soluble in ether) and is never isolated. the metal is positively polarised and the alkyl group thus is like a carbanion. it certainly behaves as a carbanion. all kinds of alkyl halides react - and amazingly, even bromobenzene and other aryl bromides and iodides react easily with magnesium. this is particularly surprising since the aromatic halogen is so unreactive. for example, it is inert to refluxing aqueous sodium hydroxide even above 200c. reactions of grignards they react vigorously with compounds with 'active' hydrogens- oh, nh and others. that's why the solution must be dry. grignards react enthusiastically with all kinds of c=o bonds. 查看更多
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