The present invention relates to a process for preparing alpha-hydroxycarboxylic esters proceeding from hydrogen cyanide, wherein the ammonia formed in the step of alcoholysis of the corresponding alpha-hydroxycarboxamide is recycled into a hydrogen cyanide preparation process after a purification step.

The present invention relates to a process for preparing alpha-hydroxycarboxylic esters proceeding from hydrogen cyanide, wherein the ammonia formed in the step of alcoholysis of the corresponding alpha-hydroxycarboxamide is recycled into a hydrogen cyanide preparation process after a purification step.

There is described a method of reducing polymer tar build-up in the production of methyl methacrylate and/or methacrylic acid by the acetone cyanohydrin process. In the method a stabiliser is contacted with the amide stage reaction medium. The stabiliser includes a hydrocarbon moiety capable of donating a labile hydrogen atom to a methacrylamide derivative capable of reaction with said labile hydrogen atom under the conditions in the said medium. The method herein is especially useful for the continuous production of methyl methacrylate and/or methacrylic acid.

There is described a method of reducing polymer tar build-up in the production of methyl methacrylate and/or methacrylic acid by the acetone cyanohydrin process. In the method a stabiliser is contacted with the amide stage reaction medium. The stabiliser includes a hydrocarbon moiety capable of donating a labile hydrogen atom to a methacrylamide derivative capable of reaction with said labile hydrogen atom under the conditions in the said medium. The method herein is especially useful for the continuous production of methyl methacrylate and/or methacrylic acid.

There is described a method of reducing polymer tar build-up in the production of methyl methacrylate and/or methacrylic acid by the acetone cyanohydrin process. In the method a stabiliser is contacted with the amide stage reaction medium. The stabiliser includes a hydrocarbon moiety capable of donating a labile hydrogen atom to a methacrylamide derivative capable of reaction with said labile hydrogen atom under the conditions in the said medium. The method herein is especially useful for the continuous production of methyl methacrylate and/or methacrylic acid.

A method for converting an N,N-dialkylamide compound into an ester compound includes using a fourth period transition metal complex as a catalyst. The fourth period transition metal complex is obtained by a reaction of a precursor having a fourth period transition metal with a nitrogen-containing compound or a phosphorus-containing compound.

A method for converting an N,N-dialkylamide compound into an ester compound includes using a fourth period transition metal complex as a catalyst. The fourth period transition metal complex is obtained by a reaction of a precursor having a fourth period transition metal with a nitrogen-containing compound or a phosphorus-containing compound.

The invention relates to an esterification unit (150) and esterification process for producing crude methyl methacrylate (MMA) from methacrylamide (MAM), which enable particularly to improve the yield, meaning that the organics spent acids are low; and at the same time, providing crude MMA with rather good quality, meaning that MMA concentration in crude MMA is rather high and preferably from 50 wt % to 80 wt %. According to the invention, the esterification unit comprises esterification reactors (1, . . . , 5 (or 6) set up in a serial way so that there is a counter current flow between gaseous phase and liquid phase, the liquid phase flowing from first reactor (1) of the series to last reactor (5 (or 6)), and the gaseous phase flowing from reactor to first reactor (1).

The invention relates to an esterification unit (150) and esterification process for producing crude methyl methacrylate (MMA) from methacrylamide (MAM), which enable particularly to improve the yield, meaning that the organics spent acids are low; and at the same time, providing crude MMA with rather good quality, meaning that MMA concentration in crude MMA is rather high and preferably from 50 wt % to 80 wt %. According to the invention, the esterification unit comprises esterification reactors (1, . . . , 5 (or 6) set up in a serial way so that there is a counter current flow between gaseous phase and liquid phase, the liquid phase flowing from first reactor (1) of the series to last reactor (5 (or 6)), and the gaseous phase flowing from reactor to first reactor (1).

The invention relates to an esterification unit (150) and esterification process for producing crude methyl methacrylate (MMA) from methacrylamide (MAM), which enable particularly to improve the yield, meaning that the organics spent acids are low; and at the same time, providing crude MMA with rather good quality, meaning that MMA concentration in crude MMA is rather high and preferably from 50 wt % to 80 wt %. According to the invention, the esterification unit comprises esterification reactors (1, . . . , 5 (or 6) set up in a serial way so that there is a counter current flow between gaseous phase and liquid phase, the liquid phase flowing from first reactor (1) of the series to last reactor (5 (or 6)), and the gaseous phase flowing from reactor to first reactor (1).