The present invention relates to a process for preparing an ester having formula R—COO—R′ (I), wherein R represents a group selected from: (i) a linear or branched alkyl, containing from 1 to 20 carbon atoms, (ii) an aryl containing from 6 to 12 carbon atoms, (iii) a heterocycle with 4 to 12 carbon atoms containing at least one heteroatom selected from O, N, P and S, R′ represents a linear or branched alkyl containing from 1 to 12 carbon atoms, said process comprising at least a phase of reacting a reaction mixture comprising at least one aldehyde having formula R—CHO (II), wherein R has the meanings defined above, and at least one alcohol having general formula R′—OH (III), wherein R′ has the meanings defined above, in the presence of at least one solid basic catalyst, at a temperature within the range of 120° C.-300° C., obtaining said ester having formula (I).

The present invention relates to a process for preparing an ester having formula R—COO—R′ (I), wherein R represents a group selected from: (i) a linear or branched alkyl, containing from 1 to 20 carbon atoms, (ii) an aryl containing from 6 to 12 carbon atoms, (iii) a heterocycle with 4 to 12 carbon atoms containing at least one heteroatom selected from O, N, P and S, R′ represents a linear or branched alkyl containing from 1 to 12 carbon atoms, said process comprising at least a phase of reacting a reaction mixture comprising at least one aldehyde having formula R—CHO (II), wherein R has the meanings defined above, and at least one alcohol having general formula R′—OH (III), wherein R′ has the meanings defined above, in the presence of at least one solid basic catalyst, at a temperature within the range of 120° C.-300° C., obtaining said ester having formula (I).

A process for continuously removing water in situ from an oxidative esterification reaction includes (a) conducting a first oxidative esterification reaction in a first reactor or reaction zone, wherein the total number of reactors or reaction zones is n and n is at least 2; (b) removing a crude product stream from the first reactor or reaction zone; (c) introducing the crude product stream to a distillation column to generate a column overheads stream and a column bottoms stream; (d) passing at least a portion of the columns bottoms stream to the product recovery zone; and (e) passing at least a portion of the column overheads stream to a subsequent reactor or reaction zone; and (f) repeating steps (a)-(e) for each subsequent reactor or reaction zone such that the number of distillation columns less than n, and wherein the at least a portion of the column overheads stream contains less than 1 weight percent (wt %) water based on the total weight of the at least a portion of the column overheads stream.

A process for continuously removing water in situ from an oxidative esterification reaction includes (a) conducting a first oxidative esterification reaction in a first reactor or reaction zone, wherein the total number of reactors or reaction zones is n and n is at least 2; (b) removing a crude product stream from the first reactor or reaction zone; (c) introducing the crude product stream to a distillation column to generate a column overheads stream and a column bottoms stream; (d) passing at least a portion of the columns bottoms stream to the product recovery zone; and (e) passing at least a portion of the column overheads stream to a subsequent reactor or reaction zone; and (f) repeating steps (a)-(e) for each subsequent reactor or reaction zone such that the number of distillation columns less than n, and wherein the at least a portion of the column overheads stream contains less than 1 weight percent (wt %) water based on the total weight of the at least a portion of the column overheads stream.

A process for removing water from an oxidative esterification reactor includes (a) conducting an oxidative esterification reaction in a reactor; (b) removing a crude product stream from the reactor; (c) passing a first portion of the crude product stream directly to a product recovery zone; (d) introducing a second portion of the crude product stream to a distillation column to generate a column overheads stream and a column bottoms stream; (e) passing at least a portion of the columns bottoms stream to the product recovery zone; and (f) recycling a recycle stream comprising at least a portion of the overheads stream to the reactor; wherein the recycle stream contains less than 1 weight percent (wt %) water based on the total weight of the recycle stream, wherein the weight ratio of the first portion to the second portion is at least 1:10, and wherein the amount of the recycle stream recycled to the reactor is such that the reactor contains less than or equal to 2.5 wt % water, based on the weight of the reactor contents.

A process for removing water from an oxidative esterification reactor includes (a) conducting an oxidative esterification reaction in a reactor; (b) removing a crude product stream from the reactor; (c) passing a first portion of the crude product stream directly to a product recovery zone; (d) introducing a second portion of the crude product stream to a distillation column to generate a column overheads stream and a column bottoms stream; (e) passing at least a portion of the columns bottoms stream to the product recovery zone; and (f) recycling a recycle stream comprising at least a portion of the overheads stream to the reactor; wherein the recycle stream contains less than 1 weight percent (wt %) water based on the total weight of the recycle stream, wherein the weight ratio of the first portion to the second portion is at least 1:10, and wherein the amount of the recycle stream recycled to the reactor is such that the reactor contains less than or equal to 2.5 wt % water, based on the weight of the reactor contents.

A process for preparing amides by reacting a primary amine and a primary alcohol in the presence of a Ruthenium complex to generate the amide and molecular hydrogen. Primary amines are directly acylated by equimolar amounts of alcohols to produce amides and molecular hydrogen (the only byproduct) in high yields and high turnover numbers. Also disclosed are processes for hydrogenation of amides to alcohols and amines; hydrogenation of organic carbonates to alcohols; hydrogenation of carbamates or urea derivatives to alcohols and amines; amidation of esters; acylation of alcohols using esters; coupling of alcohols with water and a base to form carboxylic acids; dehydrogenation of beta-amino alcohols to form pyrazines and cyclic dipeptides; and dehydrogenation of secondary alcohols to ketones. These reactions are catalyzed by a Ruthenium complex which is based on a dearomatized PNN-type ligand of formula A1 or precursors thereof of formulae A2 or A3.

A process for preparing amides by reacting a primary amine and a primary alcohol in the presence of a Ruthenium complex to generate the amide and molecular hydrogen. Primary amines are directly acylated by equimolar amounts of alcohols to produce amides and molecular hydrogen (the only byproduct) in high yields and high turnover numbers. Also disclosed are processes for hydrogenation of amides to alcohols and amines; hydrogenation of organic carbonates to alcohols; hydrogenation of carbamates or urea derivatives to alcohols and amines; amidation of esters; acylation of alcohols using esters; coupling of alcohols with water and a base to form carboxylic acids; dehydrogenation of beta-amino alcohols to form pyrazines and cyclic dipeptides; and dehydrogenation of secondary alcohols to ketones. These reactions are catalyzed by a Ruthenium complex which is based on a dearomatized PNN-type ligand of formula A1 or precursors thereof of formulae A2 or A3.

A process for preparing amides by reacting a primary amine and a primary alcohol in the presence of a Ruthenium complex to generate the amide and molecular hydrogen. Primary amines are directly acylated by equimolar amounts of alcohols to produce amides and molecular hydrogen (the only byproduct) in high yields and high turnover numbers. Also disclosed are processes for hydrogenation of amides to alcohols and amines; hydrogenation of organic carbonates to alcohols; hydrogenation of carbamates or urea derivatives to alcohols and amines; amidation of esters; acylation of alcohols using esters; coupling of alcohols with water and a base to form carboxylic acids; dehydrogenation of beta-amino alcohols to form pyrazines and cyclic dipeptides; and dehydrogenation of secondary alcohols to ketones. These reactions are catalyzed by a Ruthenium complex which is based on a dearomatized PNN-type ligand of formula A1 or precursors thereof of formulae A2 or A3.

A process is useful for producing optical molding materials on the basis of methyl methacrylate (MMA), wherein this MMA has been produced by an optimized method and the molding materials feature in particular a very low yellowness index. This MMA has been produced by direct oxidative esterification of methacrolein. In particular, an optimized workup of the reactor output from the oxidative esterification of methacrolein is useful for removing particularly discoloring byproducts. This process moreover has the advantage that fewer demands than described in related art are placed on plant apparatus configuration.