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 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 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.

Polymerizable compounds, processes and intermediates for their preparation, compositions containing them, polymers made from the compounds or compositions, and uses of the polymerizable compounds, compositions and polymers.

Polymerizable compounds, processes and intermediates for their preparation, compositions containing them, polymers made from the compounds or compositions, and uses of the polymerizable compounds, compositions and polymers.

A process for the preparation of a polyunsaturated thiol comprising: (1) reacting a polyunsaturated alcohol in the presence of a compound of formula R.sub.2—SO.sub.2Hal wherein R.sub.2 is a C.sub.1-20 hydrocarbyl group, such an C.sub.1-10 alkyl group, to form a polyunsaturated sulphonyl ester; (2) converting the polyunsaturated sulphonyl ester to a polyunsaturated thioester by reacting with an anion of formula .sup.−SC(═O)R.sub.4 wherein R.sub.4 is a C.sub.1-20 hydrocarbyl group; (3) converting the polyunsaturated thioester to form a polyunsaturated thiol optionally in the presence of an antioxidant, e.g. using a metal carbonate. (4) reacting said polyunsaturated thiol with a compound (LG)R.sup.3COX wherein X is an electron withdrawing group and R.sup.3 is an alkylene group carrying a leaving group (LG), such as LG-CH.sub.2— forming

##STR00001## where X is an electron withdrawing group and LG is a leaving group; optionally in the presence of an antioxidant, so as to form a polyunsaturated ketone compound.

A process for the preparation of a polyunsaturated thiol comprising: (1) reacting a polyunsaturated alcohol in the presence of a compound of formula R.sub.2—SO.sub.2Hal wherein R.sub.2 is a C.sub.1-20 hydrocarbyl group, such an C.sub.1-10 alkyl group, to form a polyunsaturated sulphonyl ester; (2) converting the polyunsaturated sulphonyl ester to a polyunsaturated thioester by reacting with an anion of formula .sup.−SC(═O)R.sub.4 wherein R.sub.4 is a C.sub.1-20 hydrocarbyl group; (3) converting the polyunsaturated thioester to form a polyunsaturated thiol optionally in the presence of an antioxidant, e.g. using a metal carbonate. (4) reacting said polyunsaturated thiol with a compound (LG)R.sup.3COX wherein X is an electron withdrawing group and R.sup.3 is an alkylene group carrying a leaving group (LG), such as LG-CH.sub.2— forming

##STR00001## where X is an electron withdrawing group and LG is a leaving group; optionally in the presence of an antioxidant, so as to form a polyunsaturated ketone compound.

A process for the preparation of a polyunsaturated thiol comprising: (1) reacting a polyunsaturated alcohol in the presence of a compound of formula R.sub.2—SO.sub.2Hal wherein R.sub.2 is a C.sub.1-20 hydrocarbyl group, such an C.sub.1-10 alkyl group, to form a polyunsaturated sulphonyl ester; (2) converting the polyunsaturated sulphonyl ester to a polyunsaturated thioester by reacting with an anion of formula .sup.−SC(═O)R.sub.4 wherein R.sub.4 is a C.sub.1-20 hydrocarbyl group; (3) converting the polyunsaturated thioester to form a polyunsaturated thiol optionally in the presence of an antioxidant, e.g. using a metal carbonate. (4) reacting said polyunsaturated thiol with a compound (LG)R.sup.3COX wherein X is an electron withdrawing group and R.sup.3 is an alkylene group carrying a leaving group (LG), such as LG-CH.sub.2— forming

##STR00001## where X is an electron withdrawing group and LG is a leaving group; optionally in the presence of an antioxidant, so as to form a polyunsaturated ketone compound.

The invention relates to an improved process for preparing unsymmetrical dialkyl sulfides by reacting a monoalkyl sulfide with at least one alkyl halide in the presence of base.

The invention relates to an improved process for preparing unsymmetrical dialkyl sulfides by reacting a monoalkyl sulfide with at least one alkyl halide in the presence of base.