No abstract

A number of years have elapsed since the last comprehensive review of the chemical properties of carbonyl sulfide (COS) was presented in 1957. Since that time, some important new issues have arisen regarding this fluid. The presence of COS in industrial product streams has always been an important consideration for chemical engineers. An example of a relatively new industrial issue is the presence of naturally occurring COS in liquefied petroleum gas (LPG). It is believed that the hydrolysis of this COS is the cause of corrosion and compliance-testing failures in the LPG industry. New applications of COS have arisen in recent years, such as its use as an agricultural fumigant. Environmental issues also have become more of a concern recently. These issues, as well as many other chemical and physical property issues in science and industry, make this an appropriate time to revisit the chemistry of this interesting fluid, paying special attention to recent observations. In this review, we treat the chemical preparation of COS, its major physical properties, and its major chemical reactions, and then we discuss engineering consequences, applications, and environmental issues.

No abstract

Several computational methods including the conductor-like polarizable continuum model, CPCM with both UAKS and UAHF cavities, Cramer and Truhlar's generalized Born solvation model, SM5.4(AM1), SM5.4(PM3), and SM5.43R(mPW1PW91/6-31+G(d)), and mixed QM/MM-Ewald simulations were used to calculate the pK(a) values of acetate and bicarbonate anions in aqueous solution. This work provided a critical and comprehensive assessment of the quality of these theoretical models in the calculation of aqueous solvation free energies for the singly charged acetate and bicarbonate ions, as well as the doubly charged acetate dianion and carbonate dianion. It was shown that QM/MM-Ewald simulations could give an accurate and consistent evaluation of the pK(a) values of acetate and bicarbonate based on both the relative and absolute pK(a) formulas, while other methods could yield satisfactory results only for certain calculations. However, this does not mean that the current QM/MM-Ewald protocol is superior to other methods. The useful information obtained in this investigation is that both the absolute and relative pK(a) formulas should better be tested in accurate calculations of pK(a) values based on any methods.