The invention relates to a process for preparing a semi-aromatic polyamide from diamine and dicarboxylic acid, comprising steps of •(i) dosing a liquid diamine to an agitated powder comprising an aromatic dicarboxylic acid thereby forming a powder comprising a diamine/dicarboxylic acid salt (DD-salt), and •(ii) solid-state polymerizing the DD-salt to obtain the polyamide.

The invention relates to a process for preparing a semi-aromatic polyamide from diamine and dicarboxylic acid, comprising steps of •(i) dosing a liquid diamine to an agitated powder comprising an aromatic dicarboxylic acid thereby forming a powder comprising a diamine/dicarboxylic acid salt (DD-salt), and •(ii) solid-state polymerizing the DD-salt to obtain the polyamide.

Processes are described for purifying a biphenyldicarboxylic acid product containing one or more impurities, particularly at least formylbiphenylcarboxylic acid. In the processes, a mixture comprising the biphenyldicarboxylic acid product is contacted with hydrogen in the presence of a hydrogenation catalyst under conditions to selectively reduce at least part of the formylbiphenylcarboxylic acid to produce a hydrogenation effluent comprising (i) hydroxymethylbiphenylcarboxylic acid and/or methylbiphenylcarboxylic acid, and (ii) biphenylcarboxylic acid. At least a portion of the biphenyldicarboxylic acid is then separated from the hydrogenation effluent. Advantageously, a polyester product may be produced from the separated biphenyldicarboxylic acid.

Processes are described for purifying a biphenyldicarboxylic acid product containing one or more impurities, particularly at least formylbiphenylcarboxylic acid. In the processes, a mixture comprising the biphenyldicarboxylic acid product is contacted with hydrogen in the presence of a hydrogenation catalyst under conditions to selectively reduce at least part of the formylbiphenylcarboxylic acid to produce a hydrogenation effluent comprising (i) hydroxymethylbiphenylcarboxylic acid and/or methylbiphenylcarboxylic acid, and (ii) biphenylcarboxylic acid. At least a portion of the biphenyldicarboxylic acid is then separated from the hydrogenation effluent. Advantageously, a polyester product may be produced from the separated biphenyldicarboxylic acid.

A process for oxidizing methyl-substituted biphenyl compounds comprises contacting a mixture comprising isomers of at least one methyl-substituted biphenyl compound with a source of oxygen, wherein the mixture comprises at least 20 wt % of isomer(s) having a methyl group at a 2-position or a 3-position on at least one benzene ring and at least 50 wt % of isomer(s) having a methyl group at a 4-position on at least one benzene ring, wherein said percentages are based on the total weight of the at least one methylbiphenyl compound in the mixture.

A process for oxidizing methyl-substituted biphenyl compounds comprises contacting a mixture comprising isomers of at least one methyl-substituted biphenyl compound with a source of oxygen, wherein the mixture comprises at least 20 wt % of isomer(s) having a methyl group at a 2-position or a 3-position on at least one benzene ring and at least 50 wt % of isomer(s) having a methyl group at a 4-position on at least one benzene ring, wherein said percentages are based on the total weight of the at least one methylbiphenyl compound in the mixture.

The method according to this disclosure is a method for separating an unsaturated hydrocarbon having 2 or 3 carbon atoms and a halogenated unsaturated carbon compound formed by replacing at least one of hydrogen atoms included in the unsaturated hydrocarbon with a fluorine atom, from each other and is a method for selectively adsorbing either the unsaturated hydrocarbon or the halogenated unsaturated carbon compound by a porous coordination polymer that includes a metallic ion having a valence of 2 to 4 and an aromatic anion having 1 to 6 aromatic ring(s).

A process for selective oxidation of at least one dimethylbiphenyl compound to the corresponding biphenyldicarboxylic acid, where the dimethylbiphenyl compound is supplied to at least one reaction zone together with an acidic solvent, an oxidizing medium, and a catalyst comprising cobalt, manganese, and bromine. The dimethyl biphenyl compound and oxidizing medium are contacted with the catalyst in the at least one reaction zone at a temperature of 150 to 210 C. to oxidize the dimethylbiphenyl compound to the corresponding biphenyldicarboxylic acid. The supply of dimethylbiphenyl compound to the at least one reaction zone is then terminated, but the supply of oxidizing medium and catalyst is continued with the at least one reaction zone at a temperature of 150 to 210 C. A reaction product comprising at least 95 wt % of the biphenyldicarboxylic acid based on the total weight of oxidized dimethylbiphenyl compound is then recovered from the at least one reaction zone.

A process for selective oxidation of at least one dimethylbiphenyl compound to the corresponding biphenyldicarboxylic acid, where the dimethylbiphenyl compound is supplied to at least one reaction zone together with an acidic solvent, an oxidizing medium, and a catalyst comprising cobalt, manganese, and bromine. The dimethyl biphenyl compound and oxidizing medium are contacted with the catalyst in the at least one reaction zone at a temperature of 150 to 210 C. to oxidize the dimethylbiphenyl compound to the corresponding biphenyldicarboxylic acid. The supply of dimethylbiphenyl compound to the at least one reaction zone is then terminated, but the supply of oxidizing medium and catalyst is continued with the at least one reaction zone at a temperature of 150 to 210 C. A reaction product comprising at least 95 wt % of the biphenyldicarboxylic acid based on the total weight of oxidized dimethylbiphenyl compound is then recovered from the at least one reaction zone.

Processes are described for purifying a biphenyldicarboxylic acid product containing one or more impurities, particularly at least formylbiphenylcarboxylic acid. In the processes, a mixture comprising the biphenyldicarboxylic acid product is contacted with hydrogen in the presence of a hydrogenation catalyst under conditions to selectively reduce at least part of the formylbiphenylcarboxylic acid to produce a hydrogenation effluent comprising (i) hydroxymethylbiphenylcarboxylic acid and/or methylbiphenylcarboxylic acid, and (ii) biphenylcarboxylic acid. At least a portion of the biphenyldicarboxylic acid is then separated from the hydrogenation effluent. Advantageously, a polyester product may be produced from the separated biphenyldicarboxylic acid.