An object of the present invention is to provide a method for manufacturing methionine capable of achieving an improvement in ammonia removal efficiency. The manufacturing method of the present invention comprises a removal step of supplying a liquid containing a methionine salt, which is obtained by reacting 3-methylmercaptopropionaldehyde and hydrocyanic acid, or a compound obtained by reacting 3-methylmercaptopropionaldehyde and hydrocyanic acid, with carbon dioxide and ammonia to obtain a liquid containing 5-(2-methylmercaptoethyl)hydantoin and then hydrolyzing the 5-(2-methylmercaptoethyl)hydantoin, to a diffusion tower from an upper portion thereof while supplying a stripping gas to the diffusion tower from a lower portion thereof to remove ammonia contained in the liquid through stripping, and the stripping gas contains a process gas generated in a process of manufacturing methionine.

The present invention includes pharmaceutical composition comprising (2R,2R)-3,3-disulfanediyl bis(2-acetamidopropanamide)(diNACA) or D.sub.3-N-acetyl cysteine amide, or a physiologically acceptable salt thereof, having a deuterium enrichment above the natural abundance of deuterium, and derivatives or solids thereof, and methods of using diNACA to treat eye diseases and other diseases associated with oxidative damage including, e.g., antivenom, beta-thallassemia, cataract, chronic obstructive pulmonary disease, macular degeneration, contrast-induced nephropathy, asthma, lung contusion, methamphetamine-induced oxidative stress, multiple sclerosis, Parkinson's disease, platelet apoptosis, Tardive dyskinesia, Alzheimer disease, HIV-1-associated dementia, mitochondrial diseases, myocardial myopathy, neurodegenerative diseases, pulmonary fibrosis, skin pigmentation, skin in need of rejuventation, antimicrobial infection, Friedreich's ataxia.

The present invention includes pharmaceutical composition comprising (2R,2R)-3,3-disulfanediyl bis(2-acetamidopropanamide)(diNACA) or D.sub.3-N-acetyl cysteine amide, or a physiologically acceptable salt thereof, having a deuterium enrichment above the natural abundance of deuterium, and derivatives or solids thereof, and methods of using diNACA to treat eye diseases and other diseases associated with oxidative damage including, e.g., antivenom, beta-thallassemia, cataract, chronic obstructive pulmonary disease, macular degeneration, contrast-induced nephropathy, asthma, lung contusion, methamphetamine-induced oxidative stress, multiple sclerosis, Parkinson's disease, platelet apoptosis, Tardive dyskinesia, Alzheimer disease, HIV-1-associated dementia, mitochondrial diseases, myocardial myopathy, neurodegenerative diseases, pulmonary fibrosis, skin pigmentation, skin in need of rejuventation, antimicrobial infection, Friedreich's ataxia.

The present invention includes pharmaceutical composition comprising (2R,2R)-3,3-disulfanediyl bis(2-acetamidopropanamide)(diNACA) or D.sub.3-N-acetyl cysteine amide, or a physiologically acceptable salt thereof, having a deuterium enrichment above the natural abundance of deuterium, and derivatives or solids thereof, and methods of using diNACA to treat eye diseases and other diseases associated with oxidative damage including, e.g., antivenom, beta-thallassemia, cataract, chronic obstructive pulmonary disease, macular degeneration, contrast-induced nephropathy, asthma, lung contusion, methamphetamine-induced oxidative stress, multiple sclerosis, Parkinson's disease, platelet apoptosis, Tardive dyskinesia, Alzheimer disease, HIV-1-associated dementia, mitochondrial diseases, myocardial myopathy, neurodegenerative diseases, pulmonary fibrosis, skin pigmentation, skin in need of rejuventation, antimicrobial infection, Friedreich's ataxia.

A method for producing a polythiol compound includes reacting a polyol compound with thiourea in which a content of ammonium thiocyanate is 0.05% by mass or less to obtain an isothiuronium salt.

A method for producing a polythiol compound includes reacting a polyol compound with thiourea in which a content of ammonium thiocyanate is 0.05% by mass or less to obtain an isothiuronium salt.

A production method in which a mercaptophenol compound is obtained using an industrially preferred sulfur atom introduction reaction, and intermediate compounds of the mercaptophenol compound are provided. A method for producing a mercaptophenol compound in which a phenyl carbamate compound is produced using a phenol compound as a raw material, and then a sulfur atom is regioselectively introduced by a reaction with sulfur monochloride, and a phenyl mercaptocarbamate compound is produced as an intermediate.

A production method in which a mercaptophenol compound is obtained using an industrially preferred sulfur atom introduction reaction, and intermediate compounds of the mercaptophenol compound are provided. A method for producing a mercaptophenol compound in which a phenyl carbamate compound is produced using a phenol compound as a raw material, and then a sulfur atom is regioselectively introduced by a reaction with sulfur monochloride, and a phenyl mercaptocarbamate compound is produced as an intermediate.

A production method in which a mercaptophenol compound is obtained using an industrially preferred sulfur atom introduction reaction, and intermediate compounds of the mercaptophenol compound are provided. A method for producing a mercaptophenol compound in which a phenyl carbamate compound is produced using a phenol compound as a raw material, and then a sulfur atom is regioselectively introduced by a reaction with sulfur monochloride, and a phenyl mercaptocarbamate compound is produced as an intermediate.

The present invention relates to a method for producing a specified -amino acid, the method including allowing a specified -amino acid amide and water to react with each other in the presence of a zirconium compound which contains zirconium and at least one metal element selected from the group consisting of lithium, nickel, copper, zinc, cesium, barium, hafnium, tantalum, cerium, and dysprosium.