初来扎到，想咨询下楼主，无醛乙醇除了国标规定的制取方法外有其余的好的办法么？利用国标做出来的效果达不到要求，希望能知道答案 [/quote]
Ethanol [64-17-51 M 46.1, b 78.3O, d15 0.79360, d5 0.78506, n 1.36139, pKZ5 15.93. Usual
impurities of fermentation alcohol are fusel oils (mainly higher alcohols, especially pentanols), aldehydes,
esters, ketones and water. With synthetic alcohol, likely impurities are water, aldehydes, aliphatic esters,
acetone and diethyl ether. Traces of *benzene are present in ethanol that has been dehydrated by azeotropic
distillation with *benzene. Anhydrous ethanol is very hygroscopic. Water (down to 0.05%) can be detected by
formation of a voluminous ppte when aluminium ethoxide in *benzene is added to a test portion, Rectified spirit (95% ethanol) is converted to absolute (99.5%) ethanol by refluxing with freshly ignited CaO (250gL) for
6h, standing overnight and distilling with precautions to exclude moisture.
Numerous methods are available for further drying of absolute ethanol for making "Super dry ethanol". Lund
and Bjermm [Chem Ber 64 210 19311 used reaction with magnesium ethoxide, prepared by placing 5g of clean
dry magnesium turnings and 0.5g of iodine (or a few drops of CCl4), to activate the Mg, in a 2L flask, followed
by 50-75 mL of absolute ethanol, and warming the mixture until a vigorous reaction occurs. When this
subsides, heating is continued until all the magnesium is converted to magnesium ethoxide. Up to 1L of
ethanol is added and, after an hour's reflux, it is distd off. The water content should be below 0.05%. Walden,
Ulich and Laun [Z Phys Chem 114 275 19251 used amalgamated aluminium chips, prepared by degreasing
aluminium chips (by washing with Et20 and drying in a vac to remove grease from machining the Al), treating
with alkali until hydrogen was vigorously evolved, washing with H20 until the washings were weakly alkaline
and then stirring with 1% HgC12 soln. After 2min, the chips were washed quickly with H20, then alcohol, then
ether, and dried with filter paper. (The amalgam became warm.) These chips were added to the ethanol, which
was then gently warmed for several hours until evolution of hydrogen ceased. The alcohol was distd and
aspirated for some time with pure dry air. Smith [J Chem Soc 1288 19271 reacted 1L of absolute ethanol in a
2L flask with 7g of clean dry sodium, and added 25g of pure ethyl succinate 27g of pure ethyl phthalate was an
alternative), and refluxed the mixture for 2h in a system protected from moisture, and then distd the ethanol. A
modification used 40g of ethyl formate, instead, so that sodium formate separated out and, during reflux, the
excess of ethyl formate decomposed to CO and ethanol.
Drying agents suitable for use with ethanol include Linde type 4A molecular sieves, calcium metal, and CaH2.
The calcium hydride (2g) was crushed to a powder and dissolved in lOOmL absolute ethanol by gently boiling.
About 7OmL of the ethanol were distd off to remove any dissolved gases before the remainder was poured into
1L of ca 99.9% ethanol in a still, where it was boiled under reflux for 20h, while a slow stream of pure, dry
hydrogen (better use nitrogen or Ar) was passed through. It was then distd [Ruber Z Elektrochem 29 334
19231. If calcium was used for drying, about ten times the theoretical amount should be taken, and traces of
ammonia (from some calcium nitride in the Ca metal) would be removed by passing dry air into the vapour
during reflux.
Ethanol can be freed from traces of basic materials by distn from a little 2,4,6-trinitrobenzoic acid or sulfanilic
acid. *Benzene can be removed by fractional distn after adding a little water (the *benzene/water/ethanol
azeotrope distils at 64.9O); the alcohol is then redried using one of the methods described above. Alternatively,
careful fractional distn can separate *benzene as the *benzene/ethanol azeotrope (b 68.2O). Aldehydes can be
removed from ethanol by digesting with 8-log of dissolved KOH and 5-log of aluminium or zinc per L,
followed by distn. Another method is to heat under reflux with KOH (20g/L) and AgN03 (lOg/L) or to add 2.5-
3g of lead acetate in 5mL of water to 1L of ethanol, followed (slowly and without stirring) by 5g of KOH in
25mL of ethanol: after lhr the flask is shaken thoroughly, then set aside overnight before filtering and distilling.
The residual water can be removed by standing the distillate over activated aluminium amalgam for 1 week, then
filtering and distilling. Distn of ethanol from Raney nickel eliminates catalyst poisons.
Other purification procedures include pre-treatment with conc H2SO4 (3mL/L) to eliminate amines, and [i][u][b]with
KMnO4 to oxidise aldehydes, followed by refluxing with KOH to resinify aldehydes, [/b][/u][/i]and distilling to remove
traces of H3P04 and other acidic impurities after passage through silica gel, and drying over CaS04. Water can
be removed by azeotropic distn with dichloromethane (azeotrope boils at 38.1O and contains 1.8% water) or
2,2,Ctrimethylpentane.
不知道够不够详细？ 谢谢楼主的资料，很详细，不知道该说什么。 请教:
我在做一个由酮肟还原成氨基的课题,由于产物(2-氨基)很容易转化成1-氨基的杂质,所以对反应的还原试剂和条件比较苛刻.我试过用甲酸铵-甲酸-钯碳,氢气-甲醇-钯碳等体系,效果都比较差.听说可以用NaBH4就可以.可是我又找不到相关的文献.不知专家能否给出中肯的建议和类似的资料.谢谢. [quote]原帖由 [i]dsh0707[/i] 于 2008-6-13 11:25 发表 [url=http://www.6yes.com/bbs/redirect.php?goto=findpost&pid=954959&ptid=157627][img]http://www.6yes.com/bbs/images/common/back.gif[/img][/url]
请教:
我在做一个由酮肟还原成氨基的课题,由于产物(2-氨基)很容易转化成1-氨基的杂质,所以对反应的还原试剂和条件比较苛刻.我试过用甲酸铵-甲酸-钯碳,氢气-甲醇-钯碳等体系,效果都比较差.听说可以用NaBH4就可 ... [/quote]
提供你n篇文献，[attach]14707[/attach] 谢谢meiming3030,辛苦了,资料已下载.另外,我想再请教一下专家.酮肟可否转化为酰胺,条件是什么?谢谢. [quote]原帖由 [i]dsh0707[/i] 于 2008-6-16 11:15 发表 [url=http://www.6yes.com/bbs/redirect.php?goto=findpost&pid=956263&ptid=157627][img]http://www.6yes.com/bbs/images/common/back.gif[/img][/url]
谢谢meiming3030,辛苦了,资料已下载.另外,我想再请教一下专家.酮肟可否转化为酰胺,条件是什么?谢谢. [/quote]
兄弟看下附件吧！ 我是新手，想请教一下meiming3030大侠，能不能给推荐有关有机立体化学方面的书，着重讲书写手性产生的过程，即详细画出favorable transition state，以及转变成产物的过程。像手性合成－不对称反应及其应用、Principles.and.Applications.of.Asymmetric.Synthesis这样的书不错，但书里有关书写、预测过程并不够详细。英文的最好。非常感谢！:) [quote]原帖由 [i]siliang581[/i] 于 2008-6-17 22:57 发表 [url=http://www.6yes.com/bbs/redirect.php?goto=findpost&pid=957134&ptid=157627][img]http://www.6yes.com/bbs/images/common/back.gif[/img][/url]
我是新手，想请教一下meiming3030大侠，能不能给推荐有关有机立体化学方面的书，着重讲书写手性产生的过程，即详细画出favorable transition state，以及转变成产物的过程。像手性合成－不对称反应及其应用、Princip ... [/quote]
看看附件这本，还有Organic Reaction Mechanisms, 2003、Organic Stereochemistry、Chiral Auxiliaries in Cycloadditions、Chirality in Drug Research、有机化学中的立体电子效应、不对称合成、高选择性有机合成
[[i] 本帖最后由 3030583 于 2008-6-18 08:22 编辑 [/i]] 谢谢meiming3030,辛苦了,资料已下载. 非常感谢meiming3030兄！Stereoselective Heterocyclic Synthesis III是本不错的书啊。:) meiming3030专家 你好 能否提供一些关于苯腈还原成苄胺的文献 麻烦你了 [quote]原帖由 [i]hongyintao[/i] 于 2008-6-20 14:05 发表 [url=http://www.6yes.com/bbs/redirect.php?goto=findpost&pid=958538&ptid=157627][img]http://www.6yes.com/bbs/images/common/back.gif[/img][/url]
meiming3030专家 你好 能否提供一些关于苯腈还原成苄胺的文献 麻烦你了 [/quote]
兄弟下次还是请到scifinder求助区吧，呵呵。 你好,我是学植花,想转到有机和成,不知道难不难,请赐教
回复 173# 3030583 的帖子
呵呵 谢谢meiming3030的帮助 好人会有好报的 请教专家,次卤酸盐在10度左右会氧化孤立的双键吗,如果氧化,程度如何,该怎样控制?谢谢. [quote]原帖由 [i]jinchi333[/i] 于 2008-6-20 23:40 发表 [url=http://www.6yes.com/bbs/redirect.php?goto=findpost&pid=958786&ptid=157627][img]http://www.6yes.com/bbs/images/common/back.gif[/img][/url]你好,我是学植花,想转到有机和成,不知道难不难,请赐教 [/quote]
首先学习有机化学要有本科的有机化学理论基础，因为有机化学知识又多又杂，信息量非常大。然后要有较强的动手能力，还要不怕吃苦，因为搞有机合成很苦很累毒性也较大。最后就是你的决心有多大，因为你属于转行了啊。有志者事竟成，只要肯下功夫应该可以的，但也要考虑实际，花个10年时间你学成了，那就已经老了。看你自己了。什么事情都是难了不会，会了不难，所以也就不存在难与不难的说法，只要功夫深铁杵磨成针嘛。
[[i] 本帖最后由 3030583 于 2008-6-22 20:03 编辑 [/i]] [quote]原帖由 [i]dsh0707[/i] 于 2008-6-21 19:30 发表 [url=http://www.6yes.com/bbs/redirect.php?goto=findpost&pid=959036&ptid=157627][img]http://www.6yes.com/bbs/images/common/back.gif[/img][/url]
请教专家,次卤酸盐在10度左右会氧化孤立的双键吗,如果氧化,程度如何,该怎样控制?谢谢. [/quote]
兄弟你的问题我没有接触过，我做环氧化都是用m-CPBA，效果很好，不过我对次卤酸盐氧化双键感兴趣，所以我查了一下相关文献，很不幸，只查到一篇，真是凤毛麟角，提供给你：Liebigs Annalen der Chemie, (2), 171-5; 1989。不过兄弟要是底物不要求非做过氧化物，我倒觉得兄弟不妨试试m-CPBA。 [quote]原帖由 [i]3030583[/i] 于 2008-6-22 20:20 发表 [url=http://www.6yes.com/bbs/redirect.php?goto=findpost&pid=959462&ptid=157627][img]http://www.6yes.com/bbs/images/common/back.gif[/img][/url]
兄弟你的问题我没有接触过，我做环氧化都是用m-CPBA，效果很好，不过我对次卤酸盐氧化双键感兴趣，所以我查了一下相关文献，很不幸，只查到一篇，真是凤毛麟角，提供给你：Liebigs Annalen der Chemie, (2), ... [/quote]
先谢谢你的热心,我这个问题也是在合成主题产物的一个副反应,我不是在做环氧,我们做环氧一般也是用m-CPBA,效果很好.能否将你查到的Liebigs Annalen der Chemie文献传电子版的给我,我查外文文献不方便.谢谢! [quote]原帖由 [i]dsh0707[/i] 于 2008-6-23 11:42 发表 [url=http://www.6yes.com/bbs/redirect.php?goto=findpost&pid=959710&ptid=157627][img]http://www.6yes.com/bbs/images/common/back.gif[/img][/url]
先谢谢你的热心,我这个问题也是在合成主题产物的一个副反应,我不是在做环氧,我们做环氧一般也是用m-CPBA,效果很好.能否将你查到的Liebigs Annalen der Chemie文献传电子版的给我,我查外文文献不方便.谢谢! [/quote]
我是用scifinder查到的，这篇文献我也没有下载权限，兄弟是否方便时到文献互助区区求助一下。对不住啊！
