The Preparation of Sodium Borohydride by the High Temperature Reaction of Sodium Hydride with Borate Esters1
The Preparation of Sodium Borohydride by the High Temperature Reaction of Sodium Hydride with Borate Esters1
复制标题
DOI：
10.1021/ja01097a054
复制
发表时间：
1953
影响因子：
15
通讯作者：
H. Schlesinger;H. Brown;A. E. Finholt
中科院分区：
文献类型：
--
作者：
H. Schlesinger;H. Brown;A. E. Finholt
在230 ℃下用三甲氧基硼氢化钠NaBH（OCH_3）_3反硝化，得到比母体化合物更富氢的产物。但是，除非从反应混合物中连续除去硼酸甲酯，否则反应不会完全进行到硼氢化钠的形成。即使在这些条件下，反应也不是完全的，因为一些二甲氧基硼HB（OCH 3）2与硼酸甲酯一起沿着放出，并且没有得到纯的硼氢化钠。制备后者的一种简单得多的方法是在225-275 ℃下使1摩尔硼酸甲酯与4摩尔氢化钠快速反应：4 NaH + B（OCH 3）3-*NaBH +3 NaOCH 3。异丙胺从反应产物中萃取硼氢化钠，得到几乎定量产率的基本上纯的硼氢化钠。三甲氧基硼氢化钠或四甲氧基硼氢化钠以及酯，如硼酸乙酯或正丁酯，也与氢化钠反应产生三甲氧基硼氢化钠。此外，氢化锂可以通过类似的反应转化为硼氢化锂。在330-350 ℃下，氢化钠和氧化硼反应生成硼氢化钠，产率高达60%。该反应似乎遵循4 NaH +2B 2 O3-* 3 NaBO 2 + NaBH的过程，相对缓慢，并且迄今已证明不如基于氢化钠和硼酸甲酯的制备令人满意。观察到氢气在压力下与金属钠和硼酸甲酯反应，产生三甲氧基硼氢化钠和少量硼氢化钠。
By disproportionation ofsodium trimethoxyborohydride, NaBH (OCH3) 3, at 230, products richer in hydrogen than the parent compound, are obtained. But the reactions donot go completely to the formation of sodium borohydride unless methyl borate is continuously removed from the reaction mixture. Even under these conditions the reaction is not clean-cut, since some dimethoxyborine, HB (OCH3) 2, is evolved along with the methyl borate and pure sodium borohydride is not ob-tained. A far simpler method of preparation of the latter is affordedby the rapid reaction at 225-275 of one mole of methyl borate with four moles of sodiumhydride: 4NaH+ B (OCH3) 3-*NaBH,+ 3NaOCHs. Isopropylamine extracts the sodium borohydride from the reaction product and nearly quantitative yields of essentially pure sodium borohydride are obtained. Sodium trimethoxyborohydride or tetramethoxyborohydride as well as esters, such as ethyl or «-butyl borates, also react with sodium hydride to producesodium borohydride. Moreover, lithium hydride can be converted into lithium borohydride by similar reactions. At 330-350 sodium hydride and boric oxidereact to produce up to 60% yields of sodium borohydride. The reaction, which appears to follow the course: 4NaH+ 2B203-* 3NaB02+ NaBH,, is relatively slow, and has thus far proved less satisfactory than the preparation based on sodium hydride and methyl borate. The reaction of hydrogen under pressure with sodium metal and methyl borate was observed to yield sodium trimethoxyborohydride and small quantities of sodium borohydride.