THE BASIC STRENGTHS OF METHYLATED GUANIDINES
THE BASIC STRENGTHS OF METHYLATED GUANIDINES
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DOI：
10.1039/jr9510002492
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发表时间：
1951-01-01
期刊：
影响因子：
--
通讯作者：
WARBURTON, WK
中科院分区：
文献类型：
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作者：
ANGYAL, SJ;WARBURTON, WK
Davis和Elderfield （J. Amer）报道了取代胍基强度的一个有趣的异常现象。化学。SOC。， 1932, 54, 1499)。他们发现，与母体物质一样，n -甲基、n -二甲基和NN- n ' ' -三甲基衍生物的碱强度与无机氢氧化物相当，但NN ' ' -二烷基胍要弱得多，其pK约为10.3。鲍林（《化学键的性质》，1940年，第213页）试图用共振理论来解释这种反常现象；他预测NNN ' N ' -四甲基衍生物应该是一个更弱的碱（吉尔曼，“有机化学，”1943年，第2卷，第1966页）。提到鲍林的论点，惠兰（《共振理论》，1944年，第180页）评论说：“鲍林对这些事实给出了一个巧妙的解释，但这个问题可能需要进一步的实验研究。”这项调查现在已经进行，令人惊讶的结果是，要解释的异常根本不存在。
AN interesting anomaly in the base strengths of substituted guanidines was reported by Davis and Elderfield (J. Amer. Chem. SOC., 1932, 54, 1499). They found that, like the parent substance, the N-methyl, NN-dimethyl-, and NN’N”-trimethyl derivatives were bases comparable in strength with the inorganic hydroxides, but the NN’-dialkylguanidines were much weaker, having a pK, of about 10.3. Pauling (“The Nature of the Chemical ‘Bond,” 1940, p. 213) has attempted an explanation of this anomaly in terms of the resonance theory; he predicted that the NNN ‘N’-tetramethyl derivative should be an even weaker base (Gilman,“Organic Chemistry,” 1943, Vol. 2, p. 1966). Referring to his arguments, Wheland (“TheTheory of Resonance,” 1944, p. 180) commented:“An ingenious explanation of these facts has been given by Pauling, but the problem might repay further experimental investigation.” This investigation has now been carried out with the surprising result that the anomaly to be explained does not exist at all.