Abstract
It is counterintuitive that chemical reactions can be accelerated by freezing, but this amazing phenomenon was discovered as early as the 1960s. In frozen systems, the increase in reaction rate is caused by various mechanisms and the freeze concentration effect is the main reason for the observed acceleration. Some accelerated reactions have great application value in the chemistry synthesis and environmental fields; at the same time, certain reactions accelerated at low temperature during the storage of food, medicine, and biological products should cause concern. The study of reactions accelerated by freezing will overturn common sense and provide a new strategy for researchers in the chemistry field. In this review, we mainly introduce various mechanisms for accelerating reactions induced by freezing and summarize a variety of accelerated cryochemical reactions and their applications.
Highlights
Attention to frozen systems was mainly based on the practical problem of food storage in refrigerators
The reaction rate of ethylene chlorohydrin and sodium hydroxide in was increased by 1000-fold in a frozen solution [17]. This phenomenon could be explained by the freeze concentration effect: at 5 ◦C, 0.001 M initial reactant concentration, 99.9% of the frozen solution was solid, and the reaction would proceed at 1000 times the initial rate in the remaining 0.1% of liquid
Sergeev and Batyuk described in detail the kinetic equations of the reaction rates in the liquid microphase of frozen systems, the analytical expressions for the time variation of concentration of reactants or reaction products, and the extrema of the general temperature dependence of the reaction rate in the frozen solution [59]
Summary
Attention to frozen systems was mainly based on the practical problem of food storage in refrigerators. Crystallized solvents form in non-aqueous media in a frozen state This leaves liquid pockets of highly concentrated solutes where reactions occur at a faster rate. The reaction rate of ethylene chlorohydrin and sodium hydroxide in was increased by 1000-fold in a frozen solution [17] This phenomenon could be explained by the freeze concentration effect: at 5 ◦C, 0.001 M initial reactant concentration, 99.9% of the frozen solution was solid, and the reaction would proceed at 1000 times the initial rate in the remaining 0.1% of liquid. The structures of ice-like water containing “cavities” provide a rapid proton transport mechanism [8,10] During this period, the discovery of many accelerated reactions in frozen systems aroused the interest of researchers. A known reaction is accelerated apparently as a result of freezing [18] This type of reaction is explained by the freeze concentration effect. This article mainly introduces the mechanism of accelerated cryoreactions and some accelerated cryoreaction examples to provide new exploration conditions for the reactions that are difficult to carry out at room or high temperature
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
