The present invention relates to a process for the preparation of methionine comprising the step of contacting a solution or suspension comprising 2-amino-4-(methylthio)butanenitrile and/or 2-amino-4-(methylthio)butaneamide with water in the presence of a catalyst to give a methionine comprising mixture, wherein the catalyst comprises CeO.sub.2 comprising particles, wherein the CeO.sub.2 comprising particles comprise from 50 to 100 wt.-% of CeO.sub.2, have a BET surface area of from 35 to 65 m.sup.2/g measured according to DIN ISO 9277-5 (2003), a mean maximum Feret diameter x.sub.Fmax, mean of from 10 to 40 nm and a mean minimum Feret diameter x.sub.Fmin, mean of from 5 to 30 nm, both measured according to DIN ISO 9276-6 (2012).

The present invention relates to a process for the preparation of methionine comprising the step of contacting a solution or suspension comprising 2-amino-4-(methylthio)butanenitrile and/or 2-amino-4-(methylthio)butaneamide with water in the presence of a catalyst to give a methionine comprising mixture, wherein the catalyst comprises CeO.sub.2 comprising particles, wherein the CeO.sub.2 comprising particles comprise from 50 to 100 wt.-% of CeO.sub.2, have a BET surface area of from 35 to 65 m.sup.2/g measured according to DIN ISO 9277-5 (2003), a mean maximum Feret diameter x.sub.Fmax, mean of from 10 to 40 nm and a mean minimum Feret diameter x.sub.Fmin, mean of from 5 to 30 nm, both measured according to DIN ISO 9276-6 (2012).

The present invention relates to a process for the preparation of methionine comprising the step of contacting a solution or suspension comprising 2-amino-4-(methylthio)butanenitrile and/or 2-amino-4-(methylthio)butaneamide with water in the presence of a catalyst to give a methionine comprising mixture, wherein the catalyst comprises CeO.sub.2 comprising particles, wherein the CeO.sub.2 comprising particles comprise from 50 to 100 wt.-% of CeO.sub.2, have a BET surface area of from 35 to 65 m.sup.2/g measured according to DIN ISO 9277-5 (2003), a mean maximum Feret diameter x.sub.Fmax, mean of from 10 to 40 nm and a mean minimum Feret diameter x.sub.Fmin, mean of from 5 to 30 nm, both measured according to DIN ISO 9276-6 (2012).

The invention refers to the use of a particulate catalyst containing 60.0 to 99.5 wt. % ZrO.sub.2 stabilised with an oxide of the element Hf and at least one oxide of the element M, wherein M=Ce, Si, Ti, or Y, for the hydrolysis reaction of methionine amide to methionine, wherein the median particle size x.sub.50 of the particulate catalyst is in the range of from 0.8 to 9.0 mm, preferably of from 1.0 to 7.0 mm. The invention also refers to a process for preparing methionine comprising a step of contacting a solution or suspension comprising methionine amide and water with said particulate catalyst to provide a reaction mixture comprising methionine and/or its ammonium salt from which methionine can be isolated.

The invention refers to the use of a particulate catalyst containing 60.0 to 99.5 wt. % ZrO.sub.2 stabilised with an oxide of the element Hf and at least one oxide of the element M, wherein M=Ce, Si, Ti, or Y, for the hydrolysis reaction of methionine amide to methionine, wherein the median particle size x.sub.50 of the particulate catalyst is in the range of from 0.8 to 9.0 mm, preferably of from 1.0 to 7.0 mm. The invention also refers to a process for preparing methionine comprising a step of contacting a solution or suspension comprising methionine amide and water with said particulate catalyst to provide a reaction mixture comprising methionine and/or its ammonium salt from which methionine can be isolated.

The invention refers to the use of a particulate catalyst containing 60.0 to 99.5 wt. % ZrO.sub.2 stabilised with an oxide of the element Hf and at least one oxide of the element M, wherein M=Ce, Si, Ti, or Y, for the hydrolysis reaction of methionine amide to methionine, wherein the median particle size x.sub.50 of the particulate catalyst is in the range of from 0.8 to 9.0 mm, preferably of from 1.0 to 7.0 mm. The invention also refers to a process for preparing methionine comprising a step of contacting a solution or suspension comprising methionine amide and water with said particulate catalyst to provide a reaction mixture comprising methionine and/or its ammonium salt from which methionine can be isolated.

An embodiment relates to an aromatic polythiol compound for optical materials, and the aromatic polythiol compound according to the embodiment contains a phenyl group and a large number of sulfur atoms in its polythiol structure so that a polymerizable composition and an optical material obtained therefrom have excellent optical properties such as high refractive index and low specific gravity, as well as excellent mechanical properties such as low cure shrinkage; thus, they can be advantageously used for producing various plastic optical lenses such as eyeglass lenses and camera lenses.

An embodiment relates to an aromatic polythiol compound for optical materials, and the aromatic polythiol compound according to the embodiment contains a phenyl group and a large number of sulfur atoms in its polythiol structure so that a polymerizable composition and an optical material obtained therefrom have excellent optical properties such as high refractive index and low specific gravity, as well as excellent mechanical properties such as low cure shrinkage; thus, they can be advantageously used for producing various plastic optical lenses such as eyeglass lenses and camera lenses.

The present invention relates to a transition metal complex having a PNNP4 ligand, which is easy to manufacture and handle and is relatively inexpensively available, and a method for manufacturing the same, as well as a method using this transition metal complex as a catalyst for hydrogenation reduction of ketones, esters and amides to manufacture corresponding alcohols, aldehydes, hemiacetals and hemiaminals, a method using this transition metal complex as a catalyst for oxidation of alcohols, hemiacetals and hemiaminals to manufacture corresponding carbonyl compounds, and a method using this transition metal complex as a catalyst for dehydrogenation condensation between alcohols and amines to manufacture alkylamines.

The present invention relates to a transition metal complex having a PNNP4 ligand, which is easy to manufacture and handle and is relatively inexpensively available, and a method for manufacturing the same, as well as a method using this transition metal complex as a catalyst for hydrogenation reduction of ketones, esters and amides to manufacture corresponding alcohols, aldehydes, hemiacetals and hemiaminals, a method using this transition metal complex as a catalyst for oxidation of alcohols, hemiacetals and hemiaminals to manufacture corresponding carbonyl compounds, and a method using this transition metal complex as a catalyst for dehydrogenation condensation between alcohols and amines to manufacture alkylamines.