A process can be used for producing hydroxyalkyl (meth)acrylate esters, in particular hydroxyethyl methacrylate (HEMA). The process involves a first reaction of (meth)acrolein with at least one polyhydric alcohol, in particular ethylene glycol, in the presence of a first catalyst C1, wherein a first reaction product containing a cyclic acetal is obtained. The process then involves a second reaction of the first reaction product with oxygen in the presence of a second catalyst C2, wherein a second reaction product containing at least one hydroxyalkyl (meth)acrylate ester is obtained. After the first reaction, water and optionally further components, in particular (meth)acrolein and/or the polyhydric alcohol, e.g. ethylene glycol, are at least partially removed from the first reaction product.

A process can be used for producing hydroxyalkyl (meth)acrylate esters, in particular hydroxyethyl methacrylate (HEMA). The process involves a first reaction of (meth)acrolein with at least one polyhydric alcohol, in particular ethylene glycol, in the presence of a first catalyst C1, wherein a first reaction product containing a cyclic acetal is obtained. The process then involves a second reaction of the first reaction product with oxygen in the presence of a second catalyst C2, wherein a second reaction product containing at least one hydroxyalkyl (meth)acrylate ester is obtained. After the first reaction, water and optionally further components, in particular (meth)acrolein and/or the polyhydric alcohol, e.g. ethylene glycol, are at least partially removed from the first reaction product.

The invention provides a built-in micro-interface oxidation system for preparing terephthalic acid from p-xylene. The oxidation system includes a first reactor, a rectifying tower and a second reactor which are sequentially connected. A first outlet is disposed on a side wall of the first reactor; a first inlet is disposed on a side wall of the second reactor; a material inlet is disposed on a side wall of the rectifying tower; and a material outlet is disposed at a bottom of the rectifying tower. The first outlet is connected with the material inlet of the rectifying tower; the first inlet is connected with the material outlet of the rectifying tower. Micro-interface units are arranged in the first reactor and the second reactor for dispersing and crushing air into bubbles. Through disposing micro-interface units in reactors, problems of high energy consumption, high raw material consumption and low reaction efficiency are solved.

The invention provides a built-in micro-interface oxidation system for preparing terephthalic acid from p-xylene. The oxidation system includes a first reactor, a rectifying tower and a second reactor which are sequentially connected. A first outlet is disposed on a side wall of the first reactor; a first inlet is disposed on a side wall of the second reactor; a material inlet is disposed on a side wall of the rectifying tower; and a material outlet is disposed at a bottom of the rectifying tower. The first outlet is connected with the material inlet of the rectifying tower; the first inlet is connected with the material outlet of the rectifying tower. Micro-interface units are arranged in the first reactor and the second reactor for dispersing and crushing air into bubbles. Through disposing micro-interface units in reactors, problems of high energy consumption, high raw material consumption and low reaction efficiency are solved.

A process can be used for producing optical molding materials on the basis of methyl methacrylate (MMA). The MMA 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. An optimized workup of the reactor output from the oxidative esterification of methacrolein can be used for removing particularly discoloring byproducts. This process moreover has the advantage that fewer demands are placed on plant apparatus configuration.

A process can be used for producing optical molding materials on the basis of methyl methacrylate (MMA). The MMA 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. An optimized workup of the reactor output from the oxidative esterification of methacrolein can be used for removing particularly discoloring byproducts. This process moreover has the advantage that fewer demands are placed on plant apparatus configuration.

A process can be used for producing optical molding materials on the basis of methyl methacrylate (MMA). The MMA 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. An optimized workup of the reactor output from the oxidative esterification of methacrolein can be used for removing particularly discoloring byproducts. This process moreover has the advantage that fewer demands are placed on plant apparatus configuration.

The present invention relates to an optimized process for the preparation of methacrolein. Methacrolein is used in chemical synthesis particularly as an intermediate for the preparation of methacrylic acid, methyl methacrylate or even active ingredients, fragrances or flavourings. In particular the present invention relates to the optimization of the process parameters by which, inter alia, a reduction of the content of harmful dimeric methacrolein in the end product may be achieved.

The present invention relates to an optimized process for the preparation of methacrolein. Methacrolein is used in chemical synthesis particularly as an intermediate for the preparation of methacrylic acid, methyl methacrylate or even active ingredients, fragrances or flavourings. In particular the present invention relates to the optimization of the process parameters by which, inter alia, a reduction of the content of harmful dimeric methacrolein in the end product may be achieved.

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).