This invention relates to a preparation method of an ester compound that can reduce energy consumption due to convenient post-treatment process, and simultaneously, can produce products of high purities.

An esterification reaction apparatus and an esterification reaction method, the esterification reaction apparatus comprising a reaction tank having an accommodation part, in which a raw material containing carboxylic acid and alcohol is accommodated, a heating unit configured to individually heat partition regions that are partitioned into N regions in a vertical direction of the accommodation part, and a controller configured to control the heating unit so that only the partition regions in which a liquid is accommodated among the N partition regions are heated, thereby performing an esterification reaction of the raw material.

An esterification reaction apparatus and an esterification reaction method, the esterification reaction apparatus comprising a reaction tank having an accommodation part, in which a raw material containing carboxylic acid and alcohol is accommodated, a heating unit configured to individually heat partition regions that are partitioned into N regions in a vertical direction of the accommodation part, and a controller configured to control the heating unit so that only the partition regions in which a liquid is accommodated among the N partition regions are heated, thereby performing an esterification reaction of the raw material.

The invention relates to bimesogenic compounds of formula I

##STR00001##

wherein R.sup.11, R.sup.12, MG.sup.11, MG.sup.12 and CG.sup.1 have the meaning given in claim 1, to the use of bimesogenic compounds of formula I in liquid crystal media and particular to flexoelectric liquid crystal devices comprising a liquid crystal medium according to the present invention.

The invention relates to bimesogenic compounds of formula I

##STR00001##

wherein R.sup.11, R.sup.12, MG.sup.11, MG.sup.12 and CG.sup.1 have the meaning given in claim 1, to the use of bimesogenic compounds of formula I in liquid crystal media and particular to flexoelectric liquid crystal devices comprising a liquid crystal medium according to the present invention.

The invention relates to a multifunctional acrylic product having a number-average functionality f of acrylate groups greater than 2.1, which is the product of reaction by esterification and by etherification, via Michael addition reaction, between a) a polyol or a mixture of polyols R(OH).sub.m having a functionality m of at least 3 for a polyol alone or having an average functionality greater than 2.1 for a mixture of polyols, and b) the acrylic acid (R.sub.1OH) in the presence of c) at least one cyclic polycarboxylic anhydride or of its polyacid form having a carboxy functionality z of at least 2 and up to 4, the ratio r.sub.1 of number of carboxy groups of said anhydride or polyacid c) with respect to those of the acrylic acid b) r.sub.1=CO.sub.2Hc/CO.sub.2Hb being from 0.01 to 0.4 with overall r=CO.sub.2H/OH<1, said acrylic product comprising in its composition both: units A) of oligoether-ester acrylate that are derived from a) and b) and units B) of oligoester acrylate that are derived from c),
said acrylic product being a mixture of acrylic products comprising at least one acrylic product p1 chemically linking, in its molecular structure, the two types of units A) and B) as defined above.

The invention also relates to a process for preparing said product, to crosslinkable compositions comprising same and to the use thereof in coatings, sealing, moulding or composite compositions, chemical sealing compositions, 3D printing compositions or compositions for 3D objects produced layer-by-layer. One particular advantage of these compositions is their low shrinkage despite their high functionality.

The invention relates to a multifunctional acrylic product having a number-average functionality f of acrylate groups greater than 2.1, which is the product of reaction by esterification and by etherification, via Michael addition reaction, between a) a polyol or a mixture of polyols R(OH).sub.m having a functionality m of at least 3 for a polyol alone or having an average functionality greater than 2.1 for a mixture of polyols, and b) the acrylic acid (R.sub.1OH) in the presence of c) at least one cyclic polycarboxylic anhydride or of its polyacid form having a carboxy functionality z of at least 2 and up to 4, the ratio r.sub.1 of number of carboxy groups of said anhydride or polyacid c) with respect to those of the acrylic acid b) r.sub.1=CO.sub.2Hc/CO.sub.2Hb being from 0.01 to 0.4 with overall r=CO.sub.2H/OH<1, said acrylic product comprising in its composition both: units A) of oligoether-ester acrylate that are derived from a) and b) and units B) of oligoester acrylate that are derived from c),
said acrylic product being a mixture of acrylic products comprising at least one acrylic product p1 chemically linking, in its molecular structure, the two types of units A) and B) as defined above.

The invention also relates to a process for preparing said product, to crosslinkable compositions comprising same and to the use thereof in coatings, sealing, moulding or composite compositions, chemical sealing compositions, 3D printing compositions or compositions for 3D objects produced layer-by-layer. One particular advantage of these compositions is their low shrinkage despite their high functionality.

The present invention relates to a process for the preparation of dimethyl fumarate, a compound of formula I, in a purity of at least 99.0% as determined by HPLC, containing less than 400 ppm of an anion of a mineral acid and less than 5 ppm of dimethyl maleate.

The present invention relates to a process for the preparation of dimethyl fumarate, a compound of formula I, in a purity of at least 99.0% as determined by HPLC, containing less than 400 ppm of an anion of a mineral acid and less than 5 ppm of dimethyl maleate.

In a process for producing a tetrabromophthalic diester composition, a liquid reaction mixture is prepared comprising tetrabromophthalic anhydride (TBPA), a C.sub.2 to C.sub.6 polyhydric aliphatic alcohol (PAA) and an alkylene oxide (AO) selected from the group consisting of ethylene oxide and propylene oxide, said reaction mixture being substantially free of an organic solvent. While agitating the reaction mixture, the temperature of the reaction mixture is raised to at least 50° C. to allow the TBPA to react with the PAA and AO to produce a diester composition. The reaction is terminated when the diester composition has an acid value equal to or less than 0.25 mg KOH/gm of the diester composition.