无溶剂或少溶剂的固态化学反应

Solvent-Free or Less-Solvent Solid State Reactions

根据热力学,固态化学反应一般具有一旦发生就必完全的特征;但在固体之间存在组成可连续变化的溶液(固熔体)时,固态化学反应体系有可能出现化学平衡。固态化学反应还可能导致立体选择性产物、产物颗粒不易长大、最低反应温度等特征。本文特别指出,为了促进固态化学反应快速、有效、安全地发生,可使用少量溶剂而不用担心固态化学反应无平衡特征的丧失,同时获得良好流动性的反应物浆料,并因此能使用适当的搅拌技术来促进反应;其次,任何复杂的固态化学反应都可以分解成若干双组分反应,可以按一定步骤实现复杂化合物的合成或装配。因此,研究固态化学反应可能会产生更加绿色的化学过程,具有非常现实的理论和应用价值。本文以固态配位化学反应为例来说明如上理论推演结果。这里,固态配位化学反应是固体无机金属化合物与固体有机或无机配体之间的化学反应,它们与固态有机化学反应一样,可以在室温~300℃的温度下、不存在任何溶剂的情况下发生。

According to thermodynamics,solid state reactions will generally proceed to their 100%completion once they start;however,they may stop at the equilibrium state in case that there is a solid solution with continuously changing concentration.Solid state reactions also have the following characteristics:(1)they could produce stereoselective products;(2)the particle size of the products could be very small(nano-sized);(3)there is the lowest temperature for the reaction to be initiated.Here,it is particularly pointed out that a little solvent can be employed to accelerate solid state reactions with consequent safety and effectivity,but not the equilibrium;also,the solvent can make the solid mixture more fluidized,thus the mass transportation can be speeded up by a proper blender.In addition,solid state reactions can be used to assemble materials step by step,since any complex reactions can be decomposed to a series of reactions of two reactants.Consequently,studies on solid state reactions can lead to greener chemical processes.All those are demonstrated in this paper with solid state coordination reactions,which are the reactions of solid inorganic metal compounds and solid organic or inorganic ligands.The solid state coordination reactions are well known that they take place at near room temperature up to 300℃without the help of solvents,just like the solid state organic reactions.