腈钠

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腈钠是指类化合物和离子形成的盐,这类盐被认为是反应中存在的中间体。腈钠可由腈和氨基钠、取代氨基钠或金属钠反应得到。但由于腈钠的高度不稳定性,其固体的分离特别困难。[1]

乙腈钠

乙腈钠(NaCH2CN,Mr=63.0)被认为是一种白色固体,可由乙腈和NaN(SiMe3)2反应得到:[2]

CH3CN + 3 NaN(SiMe3)2乙醚→ NaCH2CN + HN(SiMe3)2 + 2 NaN(SiMe3)2

该反应中,乙腈只有1个氢原子被钠取代。

由于乙腈的α-H具有一定的酸性,因此与氨基钠液氨中反应,生成了一种被认为是NaCH2CN·xNH3或(CH2CN)-Na+·xNH3的产物。但当这种化合物在液氨中结晶时,产生的却是CH3C(=NH)NHNa(的钠盐)。[3]

乙腈钠可以和卤代烃反应:

NaCH2CN + RX → NaX + RCH2CN

苯乙腈钠

苯乙腈钠(C16H13N2Na,Mr=256.3)可由苯乙腈和金属钠直接反应得到,其产物为二聚体的钠盐:[1]

3 C6H5CH2CN + 2 Na → NaCN + C6H5CH3 + C16H13N2Na

Fred等认为苯乙腈钠的结构应该是(C6H5)HC=C=N-Na(Mr=139.1)[4]

2 (C6H5)H-C=C=N-H + 2 Na → 2 (C6H5)H-C=C=N-Na
(C6H5)H-C=C=N-Na + H2 → C6H5CH3 + NaCN (副反应)

其化学性质活泼,高温下发生分解反应,产生二苯乙烯氰化钠

2 (C6H5)H-C=C=N-Na → NaCN + (C6H5)H-C=C-H(C6H5)

它和空气中的氧气反应,得到苯甲酸和氰化钠:

2 (C6H5)H-C=C=N-Na + O2 → C6H5COOH + NaCN

它和硝酸银在无水乙醇中反应,得到相应的银盐。

腈的其它金属盐

乙腈和叔丁基锂反应,可以得到Li2CHCN。[2]

苯乙腈和钾的反应可以得到相应的钾盐,反应按如下方程式发生:[5]

2 C6H5CH2CN + 2 K → 2 C6H5HC=C=NK + H2

产物C6H5HC=C=NK对水蒸气和二氧化碳敏感,酸会将其分解,放出氰化氢。它和(C6H5)(CN)HCK有着互变异构,虽然该异构体不占主导,但能够和碘乙烷反应,产生该异构体的取代物:

(C6H5)(CN)HCK + C2H5I → (C6H5)(CN)HC(C2H5) + KI

腈的镁、铜[6]、锌盐[7]也被制得,它们和钠盐一样,都是很强的亲核试剂。这些腈的金属盐中碳氮键的三键性质之外,通过X射线分析,还有部分碳碳双键的性质。[8]

参考文献

  1. 1.0 1.1 Mary M. Rising, Tsoh-Wu Zee. SODIUM SALTS OF AROMATIC NITRILES. I. J. Am. Chem. Soc., 1928, 50 (6), pp 1699–1707. DOI: 10.1021/ja01393a028
  2. 2.0 2.1 Robert West, Gerald A. Gornowicz. Polylithium compounds. IV. Polylithiation of nitriles and the preparations of trisilyl ynamines. J. Am. Chem. Soc., 1971, 93 (7), pp 1714–1720. DOI: 10.1021/ja00736a025
  3. F. W. Bergstrom, Robert Agostinho. The Alkylation and Arylation of Aliphatic Nitriles in Liquid Ammonia. J. Am. Chem. Soc., 1945, 67 (12), pp 2152–2154. DOI: 10.1021/ja01228a025
  4. Fred W. Upson, Robert T. Maxwell, Howard M. Parmelee. STRUCTURE OF THE SALTS OF AROMATIC NITRILES. J. Am. Chem. Soc., 1930, 52 (5), pp 1971–1975. DOI: 10.1021/ja01368a031
  5. Mary M. Rising, Irving E. Muskat, Edmund W. Lowe. SALTS OF AROMATIC NITRILES. II. POTASSIUM PHENYLACETONITRILE. J. Am. Chem. Soc., 1929, 51 (1), pp 262–265. DOI: 10.1021/ja01376a033
  6. Matthew Purzycki, Wang Liu, Göran Hilmersson, et al. Metalated nitriles: N- and C-coordination preferences of Li, Mg, and Cu cations. Chem. Commun., 2013,49, 4700-4702. DOI: 10.1039/C3CC41703D
  7. Xun Yang, Dinesh Nath, and Fraser F. Fleming. Chemoselective Alkylations with N- and C-Metalated Nitriles. Org. Lett., 2015, 17 (19), pp 4906–4909 DOI: 10.1021/acs.orglett.5b02481
  8. Fraser F. Fleming , Zhiyu Zhang , Wang Liu, et al. Metalated Nitriles: Organolithium, -magnesium, and -copper Exchange of α-Halonitriles. J. Org. Chem., 2005, 70 (6), pp 2200–2205. DOI: 10.1021/jo047877r