Disclosed is a process for recovering paraxylene in which a first simulated moving bed adsorption unit is used to produce two extract streams—one rich in paraxylene and a paraxylene-rich extract stream that is lean in ethylbenzene and an ethylbenzene-rich extract stream that is lean in paraxylene- and a paraxylene-depleted raffinate stream. A significant amount of the ethylbenzene is removed in the ethylbenzene-rich extract stream (at least enough to limit buildup in the isomerization loop), so the paraxylene-depleted raffinate stream may be isomerized in the liquid phase. Avoiding vapor phase isomerization saves energy and capital, as liquid phase isomerization requires less energy and capital than the vapor phase isomerization process due to the requirement of vaporizing the paraxylene-depleted stream and the use of hydrogen, which requires an energy and capital intensive hydrogen recycle loop.

Disclosed is a process for recovering paraxylene in which a first simulated moving bed adsorption unit is used to produce two extract streams—one rich in paraxylene and a paraxylene-rich extract stream that is lean in ethylbenzene and an ethylbenzene-rich extract stream that is lean in paraxylene- and a paraxylene-depleted raffinate stream. A significant amount of the ethylbenzene is removed in the ethylbenzene-rich extract stream (at least enough to limit buildup in the isomerization loop), so the paraxylene-depleted raffinate stream may be isomerized in the liquid phase. Avoiding vapor phase isomerization saves energy and capital, as liquid phase isomerization requires less energy and capital than the vapor phase isomerization process due to the requirement of vaporizing the paraxylene-depleted stream and the use of hydrogen, which requires an energy and capital intensive hydrogen recycle loop.

Provided is an alkyldiphenylmethane protective agent, which can prevent solidification or insolubilization of a compound by protecting a functional group of the compound to achieve easy separation and purification after a reaction. An alkyldiphenylmethane compound represented by general formula (1): ##STR00001## wherein Y represents —OR.sup.19 (wherein R.sup.19 represents a hydrogen atom or an active ester-type protecting group), —NHR.sup.20 (wherein R.sup.20 represents a hydrogen atom, a C.sub.1-6 linear or branched alkyl group, or an aralkyl group), isocyanate group, an azide group, or a halogen atom, Z represents a C.sub.1-4 linear or branched alkyl group, an alkenyl group, or a cycloalkyl group, at least one of R.sup.1 to R.sup.10 represents a group represented by formula (2):
—O—R.sup.11—X-A  (2) and the others each independently represent a hydrogen atom, a halogen atom, a C.sub.1-4 alkyl group, or a C.sub.1-4 alkoxy group; R.sup.11 represents a C.sub.1-16 linear or branched alkylene group; X represents O or CONR.sup.21 (wherein R.sup.21 represents a hydrogen atom or a C.sub.1-4 alkyl group); and A represents, for example, a group represented by formula (3): ##STR00002## wherein R.sup.12, R.sup.13, and R.sup.14 may be the same or different and each independently represent a C.sub.1-6 linear or branched alkyl group or an optionally substituted aryl group; R.sup.15 represents a single bond or a C.sub.1-3 linear or branched alkylene group; and R.sup.16, R.sup.17, and R.sup.18 each independently represent a C.sub.1-3 linear or branched alkylene group.

Provided is an alkyldiphenylmethane protective agent, which can prevent solidification or insolubilization of a compound by protecting a functional group of the compound to achieve easy separation and purification after a reaction. An alkyldiphenylmethane compound represented by general formula (1): ##STR00001## wherein Y represents —OR.sup.19 (wherein R.sup.19 represents a hydrogen atom or an active ester-type protecting group), —NHR.sup.20 (wherein R.sup.20 represents a hydrogen atom, a C.sub.1-6 linear or branched alkyl group, or an aralkyl group), isocyanate group, an azide group, or a halogen atom, Z represents a C.sub.1-4 linear or branched alkyl group, an alkenyl group, or a cycloalkyl group, at least one of R.sup.1 to R.sup.10 represents a group represented by formula (2):
—O—R.sup.11—X-A  (2) and the others each independently represent a hydrogen atom, a halogen atom, a C.sub.1-4 alkyl group, or a C.sub.1-4 alkoxy group; R.sup.11 represents a C.sub.1-16 linear or branched alkylene group; X represents O or CONR.sup.21 (wherein R.sup.21 represents a hydrogen atom or a C.sub.1-4 alkyl group); and A represents, for example, a group represented by formula (3): ##STR00002## wherein R.sup.12, R.sup.13, and R.sup.14 may be the same or different and each independently represent a C.sub.1-6 linear or branched alkyl group or an optionally substituted aryl group; R.sup.15 represents a single bond or a C.sub.1-3 linear or branched alkylene group; and R.sup.16, R.sup.17, and R.sup.18 each independently represent a C.sub.1-3 linear or branched alkylene group.

Quaternary ammonium tribromides and quaternary phosphonium tribromides are recovered from an organic solvent by washing with an aqueous hydrazine solution. The hydrazine reacts to form nitrogen, hydrobromic acid and a quaternary ammonium or quaternary phosphonium monobromide. The hydrobromic acid and quaternary ammonium or quaternary phosphonium migrate to the aqueous phase, thereby effecting the removal of the tribromides from the organic solvent. The hydrobromic acid can be neutralized with a quaternary ammonium or quaternary phosphonium hydroxide to produce a quaternary ammonium or quaternary phosphonium monobromide. The monobromides produced can be reacted with elemental bromine to regenerate a tribromide brominating agent.

An object of the present invention is to provide a chemical liquid purification method which makes it possible to obtain a chemical liquid having excellent defect inhibition performance. Another object of the present invention is to provide a chemical liquid. The chemical liquid purification method according to an embodiment of the present invention is a chemical liquid purification method including obtaining a chemical liquid by purifying a substance to be purified containing an organic solvent, in which a content of the stabilizer in the substance to be purified with respect to the total mass of the substance to be purified is equal to or greater than 0.1 mass ppm and less than 100 mass ppm.

The present invention relates to the use of a stabilizing composition comprising at least one N-oxyl compound and at least one polymerization inhibitor other than an N-oxyl compound, for inhibiting transesterification catalyst degradation in a process for the synthesis of aminoalkyl (meth)acrylates. Preferably, the transesterification catalyst is a titanium organometallic compound and the stabilising composition comprises at least one N-oxyl derivative and at least one polymerization inhibitor chosen from phenolic compounds and phenothiazine compounds in a weight ratio of between 1 and 10, preferably between 4 and 10, limits inclusive.

An object of the present invention is to provide a chemical liquid purification method which makes it possible to obtain a chemical liquid having excellent defect inhibition performance. Another object of the present invention is to provide a chemical liquid. The chemical liquid purification method according to an embodiment of the present invention is a chemical liquid purification method including obtaining a chemical liquid by purifying a substance to be purified containing an organic solvent, in which a content of the stabilizer in the substance to be purified with respect to the total mass of the substance to be purified is equal to or greater than 0.1 mass ppm and less than 100 mass ppm.

A method of stabilizing perfluoro(2-methylene-4-methyl-1,3-dioxolane) (hereinafter simply referred to as a “stabilization method”), including incorporating at least one selected from the group consisting of a hydroxy group-containing fluoroaromatic compound represented by General Formula (1) below and a hydroxy group-containing fluoroaromatic compound represented by General Formula (2) below into a composition containing perfluoro(2-methylene-4-methyl-1,3-dioxolane):

##STR00001##

(in the formula, R.sup.1 to R.sup.6 each independently represent one selected from the group consisting of a fluorine atom, a perfluoroalkyl group and a hydroxy group, and at least one of R.sup.1 to R.sup.6 is a hydroxy group);

##STR00002##

(in the formula, R.sup.7 to R.sup.14 each independently represent one selected from the group consisting of a fluorine atom, a perfluoroalkyl group and a hydroxy group, and at least one of R.sup.7 to R.sup.14 is a hydroxy group).

The present invention relates to a method for stabilizing radiosynthetic intermediates used in synthesis of .sup.18F radiolabeled aromatic amino acid derivatives toward decomposition caused by beta and gamma radiations by the use of radical scavengers and/or reductants and/or antioxidants.