CARBON-DIOXIDE AS A PHOSGENE REPLACEMENT - SYNTHESIS AND MECHANISTIC STUDIES OF URETHANES FROM AMINES, CO2, AND ALKYL CHLORIDES
CARBON-DIOXIDE AS A PHOSGENE REPLACEMENT - SYNTHESIS AND MECHANISTIC STUDIES OF URETHANES FROM AMINES, CO2, AND ALKYL CHLORIDES
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DOI：
10.1021/jo00114a035
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发表时间：
1995-05-05
影响因子：
3.6
通讯作者：
PARNAS, B
中科院分区：
文献类型：
--
作者：
MCGHEE, W;RILEY, D;PARNAS, B
以胺、二氧化碳和烷基氯为原料合成了几种氨基甲酸酯。发现添加的碱对氨基甲酸酯形成的产率和选择性的影响是非常重要的，其中使用空间位阻胍碱得到最好的结果。进行了相对速率研究，给出了乙腈中氨基甲酸酯阴离子与苄基氯之间的反应性顺序，得到氨基甲酸酯：Et（2）NCO（2）（-）= Bu（2）NCO（2）（-）> t-BuNHCO（2）（-）CyNHCO（2）（-）= s-BuNHCO（2）（-）> PhNHCO（2）（-）> CyCH（2）NHCO（2）=正辛基NHCO（2）（-）= n-BuNHCO（2）（-）。用氨基甲酸二乙酯、仲丁基、苯基和正丁基酯进行速率研究，并确定活化参数为Et（2）NCO（2）（-），Δ H-双刃= 11.8 kcal/mol，Δ S-双刃= -33 eu; s-BuNHCO（2）（-），Δ H-双刃= 12.8 kcal/mol，Δ S-双刃= -33 eu; PhNHCO（2）（-），Δ H-双匕首= 14.3 kcal/mol，Δ S-双匕首= -28 eu; n-BuNHCO（2）（-），Δ H-双匕首= 23.4 kcal/mol，Δ S-双匕首= -3 eu。使用n-BuNHCO（2）（-）得到的不寻常结果促使进一步的研究表明，反应速率与二氧化碳压力成反比（20 psig CO2，k = 4.84 x 10（-4）M（-1）s（-1）; 120 psig CO2，k = 1.83 x 10（-4）M（-1）s（-1））。通过用N-15胺和C-13富集的二氧化碳进行标记研究，氮NMR光谱表明，从在乙腈中将两个二氧化碳添加到乙胺中形成了双插入产物。
Several carbamate esters were synthesized from amines, carbon dioxide, and alkyl chlorides. The effect of added base on the yield and selectivity of carbamate ester formation was found to be highly important with the use of sterically hindered guanidine bases giving the best results. Relative rate studies were carried out giving the following order of reactivity between carbamate anions in acetonitrile with benzyl chloride giving carbamate esters: Et(2)NCO(2)(-) = Bu(2)NCO(2)(-) > t-BuNHCO(2)(-) CyNHCO(2)(-) = s-BuNHCO(2)(-) > PhNHCO(2)(-) > CyCH(2)NHCO(2) = n-octylNHCO(2)(-) = n-BuNHCO(2)(-). Rate studies were carried out with the diethyl, s-butyl, phenyl, and n-butyl carbamates and activation parameters were determined to be Et(2)NCO(2)(-), Delta H-double dagger = 11.8 kcal/mol, Delta S-double dagger = -33 eu; s-BuNHCO(2)(-), Delta H-double dagger = 12.8 kcal/mol, Delta S-double dagger = -33 eu; PhNHCO(2)(-), Delta H-double dagger = 14.3 kcal/mol, Delta S-double dagger = -28 eu; n-BuNHCO(2)(-), Delta H-double dagger: = 23.4 kcal/mol, Delta S-double dagger = -3 eu. The unusual results obtained from the use of n-BuNHCO(2)(-) prompted further studies which showed that the rate of reaction was inversely dependent on carbon dioxide pressure (20 psig CO2, k = 4.84 x 10(-4) M(-1) s(-1); 120 psig CO2, k = 1.83 x 10(-4) M(-1) s(-1)). Nitrogen NMR spectroscopy indicated, via a labeling study with N-15 amines and C-13 enriched carbon dioxide, the formation of a doubly inserted product from the addition of two carbon dioxides to ethylamine in acetonitrile.