The present invention relates to a method for preparing methyl mercaptan, in batches or continuously, preferably continuously, said method including at least the following steps: a) reacting at least one hydrocarbon feedstock in the presence of hydrogen sulphide (H.sub.2S) and optionally sulphur (S) such as to form carbon disulphide (CS.sub.2) and hydrogen (H.sub.2); b) reacting said carbon disulphide (CS.sub.2) by hydrogenation in the presence of said hydrogen (H.sub.2) obtained in step a) such as to form methyl mercaptan (CH.sub.3SH), hydrogen sulphide (H.sub.2S) and possibly hydrogen (H.sub.2); c) optionally recirculating said hydrogen sulphide (H.sub.2S) formed during step b) to step a); and d) recovering the methyl mercaptan.

According to one embodiment, in producing polythiols in a manner similar to a conventional method, a polythiol having improved storage stability may be produced in a convenient manner by adjusting reaction conditions so as to prevent thiourea from remaining within products. In particular, the equivalent weight of thiourea to be used in a reaction may be adjusted to a predetermined range, thereby reducing the amount of unreacted thiourea, and thiourea may be removed once more in a sub sequent process, thereby effectively removing remaining thiourea while achieving a high yield. The polythiol thus produced does not contain residual thiourea, and thus does not show discoloration or cloudiness caused by precipitates even under prolonged storage or high-temperature conditions.

The embodiments relate to a process for preparing a polythiol composition, which comprises reacting a halogen compound or an alcohol compound with thiourea to prepare a thiouronium salt solution; and adding a basic solution to the thiouronium salt solution to hydrolyze it. The hydrolysis reaction is terminated when the area of peak A in the graph measured by gel permeation chromatography of the reactant in the hydrolysis step under certain conditions is 0.5% to 8% based on the total peak area. A tetrafunctional polythiol composition having high purity can be obtained. Thus, an optical lens having excellent color, transparency, and refractive index can be obtained.

The present invention discloses an amino mercaptan compound, preparation method thereof and use thereof in radiation protection. The compound has the structure of formula I, wherein A.sub.1, A.sub.2, R.sup.1, R.sup.2, R.sup.5, R.sup.6, and R.sup.3 and R.sup.4 are defined herein. The compound has the effects of reducing the biological damage caused by ionizing radiation, extending the survival period and survival rate of the radiated animals, and significantly alleviating the side effects of radiotherapy, and has a low toxicity. The present invention opens up a new way for protection and treatment of ionizing radiation damage. ##STR00001##

The present invention discloses an amino mercaptan compound, preparation method thereof and use thereof in radiation protection. The compound has the structure of formula I, wherein A.sub.1, A.sub.2, R.sup.1, R.sup.2, R.sup.5, R.sup.6, and R.sup.3 and R.sup.4 are defined herein. The compound has the effects of reducing the biological damage caused by ionizing radiation, extending the survival period and survival rate of the radiated animals, and significantly alleviating the side effects of radiotherapy, and has a low toxicity. The present invention opens up a new way for protection and treatment of ionizing radiation damage. ##STR00001##

The present application relates to mass spectrometry methods for use in identifying proteins or other biomolecules which are bound irreversibly by test compounds.

The present application relates to mass spectrometry methods for use in identifying proteins or other biomolecules which are bound irreversibly by test compounds.

The present invention discloses processes for producing methyl ethyl sulfide by contacting dimethyl sulfide and diethyl sulfide in the presence of a suitable catalyst. Methyl ethyl sulfide can be used as an odorant in natural gas. Integrated mercaptan and sulfide manufacturing systems and integrated methods for making mercaptans and sulfides also are disclosed.

The present invention discloses processes for producing methyl ethyl sulfide by contacting dimethyl sulfide and diethyl sulfide in the presence of a suitable catalyst. Methyl ethyl sulfide can be used as an odorant in natural gas. Integrated mercaptan and sulfide manufacturing systems and integrated methods for making mercaptans and sulfides also are disclosed.

Methods for synthesizing a mercaptan compound include the steps of contacting a nickel-molybdenum catalyst with H.sub.2S at a sulfiding temperature of less than or equal to 235 C. to form a supported sulfur-containing catalyst, and then contacting an alcohol compound or an olefin compound, H.sub.2S, and the supported sulfur-containing catalyst to form a reaction mixture containing the mercaptan compound.