Abstract: A cross-linked polyallylamine or an acid addition salt thereof has both high phosphate adsorption capability and low degree of swelling, and a medical use thereof. The cross-linked polyallylamine or an acid addition salt thereof is obtained by copolymerization of allylammonium dihydrogen phosphate with an acid addition salt of N,N?-diallyl-1,3-diaminopropane in an amount of 5 to 25 mol % with respect to the amount of the allylammonium dihydrogen phosphate, the cross-linked polyallylamine or an acid addition salt thereof having a phosphate adsorption capacity of 2.7 to 5.0 mmol/g; and a degree of swelling of 2.0 to 5.0. The cross-linked polyallylamine or an acid addition salt thereof is useful as a therapeutic or prophylactic agent for hyperphosphatemia.

Abstract: An inexpensive method for producing trimethylhydroquinone free from the problem of the disposal of waste catalyst, which method comprises the steps of: (1) reacting isophorone in the presence of an acid catalyst and recovering &bgr;-isophorone by distiiulation, (2) oxidizing the &bgr;-isophorone in the presence of amorphous carbon and a base to obtain 4-oxoisophorone, (3) reacting the 4-oxoisophorone with an acid anhydride in a liquid phase or with a carboxylic acid in a vapor phase in the presence of a solid acid catalyst to obtain trimethylhydroquinones, and (4) hydrolyzing the trimethylhydroquinones to obtaining trimethylhydroquinone.

Abstract: Adipic acid diester is caused to react with alkoxide M(OR)n, wherein R is an alkyl group and M is an alkali metal or alkaline earth metal, the reaction product is successively subjected either to coupling with halomethylstyrene followed by carbonylation, or to coupling with 2-(halomethylphenyl)propionic acid or its ester followed by decarboxylation and hydrolysis. With this process, it is possible to produce more efficiently a specific 2-substituted propionic acid, loxoprofen.

Abstract: An inexpensive method for producing trimethylhydroquinone free from the problem of the disposal of waste catalyst, which method comprises the steps of: (1) reacting isophorone in the presence of an acid catalyst and recovering &bgr;-isophorone by distillation, (2) oxidizing the &bgr;-isophorone in the presence of amorphous carbon and a base to obtain 4-oxoisophorone, (3) reacting the 4-oxoisophorone with an acid anhydride in a liquid phase or with a carboxylic acid in a vapor phase in the presence of a solid acid catalyst to obtain trimethylhydroquinones, and (4) hydrolyzing the trimethylhydroquinones to obtaining trimethylhydroquinone.

Abstract: Adipic acid diester is caused to react with alkoxide M(OR)n, wherein R is an alkyl group and M is an alkali metal or alkaline earth metal, the reaction product is successively subjected either to coupling with halomethylstyrene followed by carbonylation, or to coupling with 2-(halomethylphenyl)propionic acid or its ester followed by decarboxylation and hydrolysis. With this process, it is possible to produce more efficiently a specific 2-substituted propionic acid, loxoprofen.

Abstract: An inexpensive method for producing trimethylhydroquinone free from the problem of the disposal of waste catalyst, which method comprises the steps of: (1) reacting isophorone in the presence of an acid catalyst and recovering &bgr;-isophorone by distiiulation, (2) oxidizing the &bgr;-isophorone in the presence of amorphous carbon and a base to obtain 4-oxoisophorone, (3) reacting the 4-oxoisophorone with an acid anhydride in a liquid phase or with a carboxylic acid in a vapor phase in the presence of a solid acid catalyst to obtain trimethylhydroquinones, and (4) hydrolyzing the trimethylhydroquinones to obtaining trimethylhydroquinone.

Abstract: A mono-olefin hydrocarbon and/or a di-olefin hydrocarbon represented by the following general formula (3) is selectively produced by dehydrogenating or oxidative-dehydrogenating a mixture of any one of hydrocarbons among the hydrocarbons represented by the following general formula (1) and any one of hydrocarbons among the hydrocarbons represented by the following general formula (2), followed by distillation;

Abstract: An inexpensive method for producing trimethylhydroquinone free from the problem of the disposal of waste catalyst, which method comprises the steps of: (1) reacting isophorone in the presence of an acid catalyst and recovering &bgr;-isophorone by distillation, (2) oxidizing the &bgr;-isophorone in the presence of amorphous carbon and a base to obtain 4-oxoisophorone, (3) reacting the 4-oxoisophorone with an acid anhydride in a liquid phase or with a carboxylic acid in a vapor phase in the presence of a solid acid catalyst to obtain trimethylhydroquinones, and (4) hydrolyzing the trimethylhydroquinones to obtaining trimethylhydroquinone.

Abstract: A method for producing cyclopentadienes which comprises the step of cyclodehydration of an unsaturated carbonyl compound having a specific chemical structure in a vapor phase in the presence of a specific solid acid catalyst. The cyclopentadienes of the invention can be produced in a high yield from inexpensive starting materials through a simplified reaction process and are useful as intermediate compounds for organic synthesis.