The invention relates to a composition comprising: at least one alkane-sulphonic acid R—SO.sub.3H wherein R represents a saturated, linear or branched, hydrocarbon chain comprising from 1 to 4 carbon atoms, which can or cannot be substituted by at least one halogen atom; sulphuric acid; and optionally at least one solvent;
of which the proportions are defined in the description. The invention also relates to the use of the composition as a fatty acid esterification catalyst.

The invention relates to a composition comprising: at least one alkane-sulphonic acid R—SO.sub.3H wherein R represents a saturated, linear or branched, hydrocarbon chain comprising from 1 to 4 carbon atoms, which can or cannot be substituted by at least one halogen atom; sulphuric acid; and optionally at least one solvent;
of which the proportions are defined in the description. The invention also relates to the use of the composition as a fatty acid esterification catalyst.

The di(meth)acrylate compound of the present disclosure is represented by the following formula (1):

##STR00001##

wherein Z.sup.1a and Z.sup.1b each represent an arene ring, R.sup.1a and R.sup.1b each represent a substituent, k1 and k2 each denote an integer of not less than 0, m1 and m2 each denote an integer of 0 to 4, and at least one of m1 and m2 denotes 1 or more, R.sup.2a and R.sup.2b each represent a substituent, n1 and n2 each denote an integer of 0 to 4, m1+n1 and m2+n2 each denote 4 or less, A.sup.1a and A.sup.1b each represent a straight- or branched-chain alkylene group, A.sup.2a and A.sup.2b each represent a straight- or branched-chain alkylene group, p1 and p2 each denote an integer of not less than 0, and R.sup.3a and R.sup.3b each represent a hydrogen atom or a methyl group.

The di(meth)acrylate compound is a novel compound having a high refractive index.

The di(meth)acrylate compound of the present disclosure is represented by the following formula (1):

##STR00001##

wherein Z.sup.1a and Z.sup.1b each represent an arene ring, R.sup.1a and R.sup.1b each represent a substituent, k1 and k2 each denote an integer of not less than 0, m1 and m2 each denote an integer of 0 to 4, and at least one of m1 and m2 denotes 1 or more, R.sup.2a and R.sup.2b each represent a substituent, n1 and n2 each denote an integer of 0 to 4, m1+n1 and m2+n2 each denote 4 or less, A.sup.1a and A.sup.1b each represent a straight- or branched-chain alkylene group, A.sup.2a and A.sup.2b each represent a straight- or branched-chain alkylene group, p1 and p2 each denote an integer of not less than 0, and R.sup.3a and R.sup.3b each represent a hydrogen atom or a methyl group.

The di(meth)acrylate compound is a novel compound having a high refractive index.

The present disclosure relates to a synthetic vegetable oil and an environmental-friendly flame-retardant hydraulic oil composition including the same, and a preparation method thereof, and provides a method of preparing a glycerin-ester-based lubricating base oil through a catalyst-free and rinsing-free process, a glycerin-ester-based lubricating base oil that is a synthetic vegetable oil obtained by the method, and an environmental-friendly flame-retardant hydraulic oil composition that contains the glycerin-ester-based lubricating base oil and that is capable of reducing electricity consumption by 7 to 8% compared to mineral oil-based lubricating oils due to excellent flame retardancy (with self-extinguishing function) and lubricity.

The present disclosure relates to a synthetic vegetable oil and an environmental-friendly flame-retardant hydraulic oil composition including the same, and a preparation method thereof, and provides a method of preparing a glycerin-ester-based lubricating base oil through a catalyst-free and rinsing-free process, a glycerin-ester-based lubricating base oil that is a synthetic vegetable oil obtained by the method, and an environmental-friendly flame-retardant hydraulic oil composition that contains the glycerin-ester-based lubricating base oil and that is capable of reducing electricity consumption by 7 to 8% compared to mineral oil-based lubricating oils due to excellent flame retardancy (with self-extinguishing function) and lubricity.

In a process for purifying fatty acid alkyl esters, particularly methyl and ethyl esters, by means of vacuum distillation in a distillation column, water or steam is introduced into the distillation column and, during distillation, brought into contact with the fatty acid alkyl esters in the gas phase. This results in a significant reduction in the sulphur content and in the acid number of the fatty acid alkyl ester.

In a process for purifying fatty acid alkyl esters, particularly methyl and ethyl esters, by means of vacuum distillation in a distillation column, water or steam is introduced into the distillation column and, during distillation, brought into contact with the fatty acid alkyl esters in the gas phase. This results in a significant reduction in the sulphur content and in the acid number of the fatty acid alkyl ester.

In order to provide a chemical reaction apparatus that can suppress a situation where microwaves are concentrated on a partial portion in a reactor, and that can more uniformly irradiate a content with the microwaves, a chemical reaction apparatus includes: a horizontal flow-type reactor in which a liquid content horizontally flows with an unfilled space being provided thereabove; a microwave generator that generates microwaves; and a waveguide that transmits the microwaves generated by the microwave generator to the unfilled space in the reactor, wherein a top of the reactor is curved with respect to a flow direction of the content.

In order to provide a chemical reaction apparatus that can suppress a situation where microwaves are concentrated on a partial portion in a reactor, and that can more uniformly irradiate a content with the microwaves, a chemical reaction apparatus includes: a horizontal flow-type reactor in which a liquid content horizontally flows with an unfilled space being provided thereabove; a microwave generator that generates microwaves; and a waveguide that transmits the microwaves generated by the microwave generator to the unfilled space in the reactor, wherein a top of the reactor is curved with respect to a flow direction of the content.