The hydrochlorination of 4,4â²-methylenedianiline, NH2C6H4CH2C6H4NH2 (MDA), in chlorobenzene to produce 4,4â²-methylenedianiline dihydrochloride, [H3NC6H4CH2C6H4NH3]Cl2 (MDA·2HCl) is an important reaction for the production of isocyanates, which are used to manufacture polyurethanes. This reaction is examined here. MDA is moderately soluble in chlorobenzene, whereas MDA·2HCl is effectively insoluble. Controlled addition of anhydrous HCl to MDA in chlorobenzene led to the isolation of a solid whose stoichiometry is MDA·HCl. Crystals obtained from solutions of MDA·HCl in methanol were found by X-ray analysis to consist of the basic hydrochloride salt, [MDAH2][Cl]2[MDA]2H2O, which is stabilised by complex hydrogen-bonding. The starting material MDA has an H-bonded structure in which the molecules are linked in a one-dimensional chain. Hydrogen-bonding is extensive in MDA·2HCl which contains ladders of [H3NC6H4CH2C6H4NH3]2+ dications stabilised by NâHâ¯Cl linkages. Energy calculations on the crystalline systems allow an identification of the main factors in intermolecular cohesion; these are related to melting temperature and solubility data. Such improvements in understanding of soluteâsolute interactions are prerequisites for improving the atom economy of this important stage within the polyurethane manufacture process chain. The solid phase IR spectrum of MDA·2HCl is diagnostic, principally as a result of a Fermi resonance process.
4,4â²-亚甲基
二苯胺 NH2C6H4CH2C6H4NH2(
MDA)在
氯苯中的
盐酸化反应生成 4,4â²-亚甲基
二苯胺二盐酸盐 [H3NC6H4CH2C6H4NH3]Cl2(
MDAÂ-2HCl)是生产
异氰酸酯的一个重要反应,
异氰酸酯用于生产聚
氨酯。本文对该反应进行了研究。
MDA 在
氯苯中的溶解度适中,而
MDAÂ-2HCl 实际上是不溶的。将无
水 HCl 有控制地加入
氯苯中的
MDA 后,可分离出一种固体,其
化学计量为
MDAÂ-HCl。通过 X 射线分析发现,从
MDAÂ-HCl 在
甲醇中的溶液中获得的晶体由碱性盐酸盐 [M
DAH2][Cl]2[
MDA]2H2O组成,该盐酸盐通过复杂的氢键作用而稳定。起始原料
MDA 具有氢键结构,其中的分子以一维链的形式连接。在
MDAÂ-2HCl 中,氢键的作用非常广泛,它含有阶梯状的 [H3NC6H4CH2C6H4NH3]2+ 双阳离子,并通过 NâHâCl 链接稳定下来。通过对晶体系统的能量计算,可以确定分子间内聚力的主要因素;这些因素与熔化温度和溶解度数据有关。加深对溶质与溶质之间相互作用的理解,是提高聚
氨酯生产过程链中这一重要阶段的原子经济性的先决条件。
MDAÂ-2HCl 的固相红外光谱具有诊断性,主要是费米共振过程的结果。