A method for producing trans-bis(aminomethyl)cyclohexane includes a trans-isomerization step in which cis-dicyanocyclohexane is isomerized into trans-dicyanocyclohexane by heating dicyanocyclohexane containing cis-dicyanocyclohexane in the presence of a tar component produced by distillation of dicyanocyclohexane; and an aminomethylation step in which trans-dicyanocyclohexane produced by the trans-isomerization step is allowed to contact with hydrogen to produce trans-bis(aminomethyl)cyclohexane.

A method for preparing an aliphatic isocyanate according to an exemplary embodiment of the present disclosure includes a first step of introducing an aliphatic amine and an organic solvent into a reactor, a second step of supplying gaseous hydrogen chloride into the reactor through a sparger, and a third step of stirring the aliphatic amine and the organic solvent, and the hydrogen chloride with a stirrer installed in the reactor, wherein in the third step, a stirring force of the stirrer is controlled to 500 to 4,000 W/m.sup.3.

A method for preparing an aliphatic isocyanate according to an exemplary embodiment of the present disclosure includes a first step of introducing an aliphatic amine and an organic solvent into a reactor, a second step of supplying gaseous hydrogen chloride into the reactor through a sparger, and a third step of stirring the aliphatic amine and the organic solvent, and the hydrogen chloride with a stirrer installed in the reactor, wherein in the third step, a stirring force of the stirrer is controlled to 500 to 4,000 W/m.sup.3.

The invention relates to a method for the preparation of isocyanates. Here it is provided that (i) a first organosilicon compound having at least one silicon atom Si.sup.1 and a unit of formula G-I bound thereto ##STR00001## is converted to a third organosilicon compound having a unit of formula G-II ##STR00002## by silylation of the NH group of the unit of formula G-I with a second organosilicon compound having one silicon atom Si.sup.2; and (ii) the third organosilicon compound is reacted to an isocyanate by thermolysis, whereby the unit of formula G-II is converted to an isocyanate group.

The invention relates to a method for the preparation of isocyanates. Here it is provided that (i) a first organosilicon compound having at least one silicon atom Si.sup.1 and a unit of formula G-I bound thereto ##STR00001## is converted to a third organosilicon compound having a unit of formula G-II ##STR00002## by silylation of the NH group of the unit of formula G-I with a second organosilicon compound having one silicon atom Si.sup.2; and (ii) the third organosilicon compound is reacted to an isocyanate by thermolysis, whereby the unit of formula G-II is converted to an isocyanate group.