In the embodiments, an aqueous hydrochloric acid solution and an organic solvent instead of hydrogen chloride gas and solid triphosgene instead of phosgene gas may be used in the process of preparing a diisocyanate from a diamine through a diamine hydrochloride. In addition, the embodiments provide processes for preparing a diisocyanate composition and an optical lens, which are excellent in yield and quality with mitigated environmental problems by controlling the total content of metals, cations, or anions in a diamine hydrochloride composition.

In the embodiments, an aqueous hydrochloric acid solution and an organic solvent instead of hydrogen chloride gas and solid triphosgene instead of phosgene gas may be used in the process of preparing a diisocyanate from a diamine through a diamine hydrochloride. In addition, the embodiments provide processes for preparing a diisocyanate composition and an optical lens, which are excellent in yield and quality with mitigated environmental problems by controlling the total content of metals, cations, or anions in a diamine hydrochloride composition.

The objective of the present invention is to reduce the content of dialkylcarbamoyl chloride contained in a (meth)acrylic acid ester compound having an isocyanate group. The present invention includes a method for producing a (meth)acrylic acid ester compound having an isocyanate group in which the content of dialkylcarbamoyl chloride is 0.1 mass % or less, where the method includes a step (2) in which a predetermined compound (B) and phosgene are brought into contact in the presence of an N-disubstituted formamide compound (A) to obtain a phosgene reaction product, and a step (3) in which the phosgene reaction product obtained in step (2) and a hydroxylamine hydrochloride compound are brought into contact to obtain a (meth)acrylic acid ester compound having a predetermined isocyanate group.

The objective of the present invention is to reduce the content of dialkylcarbamoyl chloride contained in a (meth)acrylic acid ester compound having an isocyanate group. The present invention includes a method for producing a (meth)acrylic acid ester compound having an isocyanate group in which the content of dialkylcarbamoyl chloride is 0.1 mass % or less, where the method includes a step (2) in which a predetermined compound (B) and phosgene are brought into contact in the presence of an N-disubstituted formamide compound (A) to obtain a phosgene reaction product, and a step (3) in which the phosgene reaction product obtained in step (2) and a hydroxylamine hydrochloride compound are brought into contact to obtain a (meth)acrylic acid ester compound having a predetermined isocyanate group.

The objective of the present invention is to reduce the content of dialkylcarbamoyl chloride contained in a (meth)acrylic acid ester compound having an isocyanate group. The present invention includes a method for producing a (meth)acrylic acid ester compound having an isocyanate group in which the content of dialkylcarbamoyl chloride is 0.1 mass % or less, where the method includes a step (2) in which a predetermined compound (B) and phosgene are brought into contact in the presence of an N-disubstituted formamide compound (A) to obtain a phosgene reaction product, and a step (3) in which the phosgene reaction product obtained in step (2) and a hydroxylamine hydrochloride compound are brought into contact to obtain a (meth)acrylic acid ester compound having a predetermined isocyanate group.

A method of producing a thiourethane resin raw material, the method including comprising the step of generating the thiourethane resin raw material by reacting a thiourethane resin and an active hydrogen compound with each other.

A method of producing a thiourethane resin raw material, the method including comprising the step of generating the thiourethane resin raw material by reacting a thiourethane resin and an active hydrogen compound with each other.

The present invention relates to a process for preparing an isocyanate comprising the steps of (A) reacting an amine with a stoichiometric excess of phosgene using an aromatic solvent of formula C.sub.6H.sub.6-XCl.sub.X, wherein X=1 or 2, (a) as a diluent during the reaction and/or (b) as a means for cooling the reaction mixture formed from the reaction of the amine with phosgene (so-called quench) to obtain (optionally after a decompression) a liquid product mixture comprising the isocyanate and the aromatic solvent employed and a gaseous product mixture containing phosgene and hydrogen chloride; followed by (B) isolating the isocyanate from the liquid product mixture obtained in step (A) comprising the step of a final distillation in which the isolated isocyanate is obtained as a product stream, wherein in the final distillation or in a distillation step upstream of the final distillation at least one stream comprising aromatic solvent of formula C.sub.6H.sub.6-YCl.sub.Y, wherein Y=X+1, is (at intervals or continuously) discharged such that the isolated isocyanate has a mass fraction, based on its total mass, of aromatic solvent of formula C.sub.6H.sub.6-YCl.sub.Y in the range from 0.0 ppm to 9.9 ppm, preferably 0.0 ppm to 5.0 ppm, particularly preferably 0.0 ppm to 3.0 ppm.

The present invention relates to a process for preparing an isocyanate comprising the steps of (A) reacting an amine with a stoichiometric excess of phosgene using an aromatic solvent of formula C.sub.6H.sub.6-XCl.sub.X, wherein X=1 or 2, (a) as a diluent during the reaction and/or (b) as a means for cooling the reaction mixture formed from the reaction of the amine with phosgene (so-called quench) to obtain (optionally after a decompression) a liquid product mixture comprising the isocyanate and the aromatic solvent employed and a gaseous product mixture containing phosgene and hydrogen chloride; followed by (B) isolating the isocyanate from the liquid product mixture obtained in step (A) comprising the step of a final distillation in which the isolated isocyanate is obtained as a product stream, wherein in the final distillation or in a distillation step upstream of the final distillation at least one stream comprising aromatic solvent of formula C.sub.6H.sub.6-YCl.sub.Y, wherein Y=X+1, is (at intervals or continuously) discharged such that the isolated isocyanate has a mass fraction, based on its total mass, of aromatic solvent of formula C.sub.6H.sub.6-YCl.sub.Y in the range from 0.0 ppm to 9.9 ppm, preferably 0.0 ppm to 5.0 ppm, particularly preferably 0.0 ppm to 3.0 ppm.

The embodiments provide processes for preparing a diisocyanate composition and an optical lens, which are excellent in yield and quality with mitigated environmental problems by using a solid triphosgene composition instead of phosgene gas in the process of preparing a diisocyanate from a diamine through a hydrochloride thereof and by controlling the content of a decomposition product in a triphosgene composition, the b* value according to CIE color coordinate of the triphosgene composition in an organic solvent, or the content of water in the triphosgene.