Homolytic organometallic reactions. Part IV. Homolytic alkylthiyldealkylation of organoboranes
Homolytic organometallic reactions. Part IV. Homolytic alkylthiyldealkylation of organoboranes
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均相有机金属反应。
DOI：
10.1039/j29710001830
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发表时间：
1971
期刊：
影响因子：
--
通讯作者：
B. P. Roberts
中科院分区：
文献类型：
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作者：
A. G. Davies;B. P. Roberts
三烷基硼烷与1-硫醇丁烷反应生成二烷基丁基硫代硼烷，R2 BSBun，通过自由基链机制，涉及双分子均裂取代的丁基硫基自由基在硼。通过三烷基硼烷与辛烯竞争丁硫基自由基，得到了SH_2进攻硼原子和加成到烯烃上的相对速率，并考虑了丁硫基加成到烯烃上的可逆性。电子自旋共振（e.s.r.）的观察也表明了SH 2过程的发生。当含有三烷基硼烷和二烷基或二芳基二硫化物的溶液在E.S.R.的空腔中光解时，被置换的烷基的光谱。三烷基硼烷和辛-1-烯的相对反应活性的顺序为Bun 3B> Bu 13 B> Bus 3B>辛-1-烯> Bun 2BSBun。烷硫基脱烷基化的绝对速率系数与烷基过氧基和烷氧基自由基与有机硼烷的SH 2反应的绝对速率系数具有相同的量级（105-107 M-1 s-1）。
Trialkylboranes react with butane-1-thiol to give dialkylbutylthioboranes, R2BSBun, by a free radical chain mechanism involving bimolecular homolytic substitution by the butylthiyl radical at boron. By competing the trialkylborane with oct-1-ene for the butylthiyl radical relative rates of SH2 attack at boron and addition to the olefin were found. The reversibility of the addition of the thiyl radical to the olefin was taken into account. The occurrence of the SH2 process was also shown by the observation of the e.s.r. spectrum of the displaced alkyl radical when a solution containing a trialkylborane and a dialkyl or a diaryl disulphide was photolysed in the cavity of an e.s.r. spectrometer.The relative reactivities of the trialkylboranes and oct-1-ene were shown to be in the order Bun3B > Bui3B > Bus3B > oct-1-ene > Bun2BSBun. The absolute rate coefficients for alkylthiyldealkylation were of the same magnitude (105–107 M–1 s–1) as those found for the SH2 reactions of alkylperoxyl and alkoxyl radicals with organoboranes.