Disclosed is a method for separating, with a multi-stage distillation column, a mixture containing an active hydrogen-containing compound (A) and a compound (B) that reversibly reacts with the active hydrogen containing compound (A), the method comprising distillation-separating the active hydrogen-containing compound (A) and the compound (B) with the multi-stage distillation column in the presence of an intermediate-boiling-point inactive compound (C) that has a normal boiling point between a normal boiling point of the active hydrogen-containing compound (A) and a normal boiling point of the compound (B) and is chemically inactive for both of the (A) and the compound (B).

Disclosed is a method for separating, with a multi-stage distillation column, a mixture containing an active hydrogen-containing compound (A) and a compound (B) that reversibly reacts with the active hydrogen containing compound (A), the method comprising distillation-separating the active hydrogen-containing compound (A) and the compound (B) with the multi-stage distillation column in the presence of an intermediate-boiling-point inactive compound (C) that has a normal boiling point between a normal boiling point of the active hydrogen-containing compound (A) and a normal boiling point of the compound (B) and is chemically inactive for both of the (A) and the compound (B).

The present invention provides a method for producing a carbamate that includes a step (1) and a step (2) described below: (1) a step of producing a compound (A) having a urea linkage, using an organic primary amine having at least one primary amino group per molecule and at least one compound selected from among carbon dioxide and carbonic acid derivatives, at a temperature lower than the thermal dissociation temperature of the urea linkage; and (2) a step of reacting the compound (A) with a carbonate ester to produce a carbamate.

The present invention provides a method for producing a carbamate that includes a step (1) and a step (2) described below: (1) a step of producing a compound (A) having a urea linkage, using an organic primary amine having at least one primary amino group per molecule and at least one compound selected from among carbon dioxide and carbonic acid derivatives, at a temperature lower than the thermal dissociation temperature of the urea linkage; and (2) a step of reacting the compound (A) with a carbonate ester to produce a carbamate.

The present invention provides a method for producing a carbamate that includes a step (1) and a step (2) described below: (1) a step of producing a compound (A) having a urea linkage, using an organic primary amine having at least one primary amino group per molecule and at least one compound selected from among carbon dioxide and carbonic acid derivatives, at a temperature lower than the thermal dissociation temperature of the urea linkage; and (2) a step of reacting the compound (A) with a carbonate ester to produce a carbamate.

The invention relates to a process for preparing a diisocyanate of the formula (A) ##STR00001## where R is selected from the group consisting of alkyl, aryl, and combinations thereof, comprising the following process steps in the indicated order; 1) providing an intermediate of the formula (B) with a process using lysine and urea ##STR00002## and where R and each R′ are independently selected from the group consisting of alkyl, aryl, and combinations thereof; and 2) thermolytic cleavage of the intermediate of the formula (B), thereby affording the diisocyanate of the formula (A),
and also to the diisocyanate directly prepared therewith.

The invention relates to a process for preparing a diisocyanate of the formula (A) ##STR00001## where R is selected from the group consisting of alkyl, aryl, and combinations thereof, comprising the following process steps in the indicated order; 1) providing an intermediate of the formula (B) with a process using lysine and urea ##STR00002## and where R and each R′ are independently selected from the group consisting of alkyl, aryl, and combinations thereof; and 2) thermolytic cleavage of the intermediate of the formula (B), thereby affording the diisocyanate of the formula (A),
and also to the diisocyanate directly prepared therewith.

There are provided a method of producing a carbonyl compound by a flow type reaction, including introducing a triphosgene solution, a tertiary amine solution, and an active hydrogen-containing compound solution into flow channels different from each other to cause the respective solutions to flow inside the respective flow channels, joining the respective solutions that flow inside the respective flow channels simultaneously or sequentially so that a reaction between phosgene and an active hydrogen-containing compound occurs, and obtaining a carbonyl compound in a joining solution, in which a non-aqueous organic solvent is used as a solvent of each of the respective solutions and a compound having a cyclic structure is used as the tertiary amine; and a flow type reaction system that is suitable for carrying out this production method.

There are provided a method of producing a carbonyl compound by a flow type reaction, including introducing a triphosgene solution, a tertiary amine solution, and an active hydrogen-containing compound solution into flow channels different from each other to cause the respective solutions to flow inside the respective flow channels, joining the respective solutions that flow inside the respective flow channels simultaneously or sequentially so that a reaction between phosgene and an active hydrogen-containing compound occurs, and obtaining a carbonyl compound in a joining solution, in which a non-aqueous organic solvent is used as a solvent of each of the respective solutions and a compound having a cyclic structure is used as the tertiary amine; and a flow type reaction system that is suitable for carrying out this production method.

Disclosed is a process for the synthesis of pimavanserin base with a high yield and purity, which comprises: a) converting tert-butyl-N-[(4-propan-2-yloxyphenyl)methyl]carbamate (Formula (I)) to 1-(isocyanatomethyl)-4-propan-2-yloxybenzene of formula (II) b) adding N-[(4-fluorophenyl)methyl]-1-methylpiperidin-4-amine (Formula (IV)) to the solution obtained in a) to give pimavanserin base, and c) purifying the pimavanserin base obtained in step b). ##STR00001##