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苯硫酚与苯乙炔、对溴苯乙炔、对硝基苯乙炔及丙炔酸在室温进行直接加成时,生成相应的1:1加成物,其主体构型均属反式,分别为反-β-苯硫基苯乙烯(Ⅰa),反-β-苯硫基对溴苯乙烯(Ⅱa),反-β-苯硫基对硝基苯乙烯(Ⅲa)及反-β-苯硫基丙烯酸(Ⅳa)。加成物的得率按以下顺序而递減:Ⅰa>Ⅱa>Ⅲa>Ⅳa。在低温(-45～-35°)苯硫酚与四种炔烃在溶液中反应时,除对硝基苯乙炔不起反应外,其它三种炔化合物均给出全部或绝大部分顺式构型产物(反式加成),分别为顺-β-苯硫基苯乙烯(Ⅰb,100％),顺-β-苯硫基对溴苯乙烯(Ⅱb,75％)及顺-β-苯硫基丙烯酸(Ⅳb,80％)。所有顺式构型产物在反应条件下都稳定,只是在加热到160°以上时才转化为反式构型产物。苯硫酚对炔烃的直接加成为一自由基反应,所观察到的立体化学结果被解释为加成反应中形成的中间体自由基(Ⅴ),由于R(苯基或羧基)与处于顺式位置的C_6H_5S基的空间位阻,在与苯硫酚进行链转移之前发生异构化所致。因为Ⅴ的异构化为Ⅵ需要一定的活化能,故在低温下的加成全部或绝大部分按反式加成进行,在温度升高时全部转为顺式加成。苯硫酚与对硝基苯乙炔在无水乙醚中在—60°形成一深紫色溶液,两小时后颜色逐渐变淡,这似乎表明有自由基的形成。苯硫酚与四种炔化合物在乙氧基负离子催化下进行加成时,得到全部为反式加成的产物,分别为Ⅰb,Ⅱb,顺-β-苯硫基对硝基苯乙烯(Ⅲb)及Ⅳb。
Thiophenol and phenylacetylene, p-bromo phenylacetylene, p-nitrophenylacetylene and propynoic acid at room temperature when the direct addition, the formation of the corresponding 1: 1 adduct, the main configuration is trans, were Β-phenylthio styrene (Ia), trans-β-phenylthio-p-bromostyrene (IIa), trans-β-phenylthio p-nitrostyrene (IIIa) Acrylic acid (IVa). The adduct yield decreases in the following order: Ia> IIa> IIIa> IVa. In the low temperature (-45 ~ -35 °) thiophenol with four alkynes in solution reaction, in addition to p-nitrophenylacetylene can not react, the other three alkyne compounds are given all or most of the cis Β-phenylthiostyrene (Ib, 100%), cis-β-phenylthio-p-bromostyrene (Ⅱb, 75%) and cis-β- Phenylthioacrylic acid (IVb, 80%). All cis configuration products are stable under the reaction conditions and are only converted to trans configuration products when heated above 160 ° C. The direct addition of the thiophenol to the alkyne is a free radical reaction. The observed stereochemical results are interpreted as intermediate free radicals formed in the addition reaction (V). Since R (phenyl or carboxyl) The steric hindrance of the C_6H_5S group in the formula isomerised prior to chain transfer with thiophenol. Because of the isomerization of V to VI requires a certain activation energy, so all or most of the addition at low temperature by trans-addition, all at temperature increases into cis-addition. Thiophenol and p-nitrophenylacetylene formed a dark violet solution at -60 ° in anhydrous ether, gradually fades color after two hours, which seems to indicate the formation of free radicals. Thiophenol and four alkyne compounds in the ethoxy anion catalyzed addition, all the trans addition products were obtained, respectively, Ⅰ b, Ⅱ b, cis-β-phenylthio p-nitrostyrene (Ⅲ b ) And IVb.