A composition is provided including a compound (A) represented by Formula (1) and a compound (B) represented by Formula (2), wherein the compound (B) is contained in an amount of 0.00002 to 0.2 parts by mass with respect to 100 parts by mass of the compound (A): (R.sub.1—COO).sub.n—R.sub.2—(NCO).sub.m . . . (1) (in Formula (1), R.sub.1 is an ethylenically unsaturated group having 2 to 7 carbon atoms; R.sub.2 is an (m+n)-valent hydrocarbon group having 1 to 7 carbon atoms; and n and m are each an integer of 1 or 2) ##STR00001##
(in Formula (2), R is (—R.sub.2—(OCO—R.sub.1), and R.sub.1 and R.sub.2 are the same as those in Formula (1)).

A composition is provided including a compound (A) represented by Formula (1) and a compound (B) represented by Formula (2), wherein the compound (B) is contained in an amount of 0.00002 to 0.2 parts by mass with respect to 100 parts by mass of the compound (A): (R.sub.1—COO).sub.n—R.sub.2—(NCO).sub.m . . . (1) (in Formula (1), R.sub.1 is an ethylenically unsaturated group having 2 to 7 carbon atoms; R.sub.2 is an (m+n)-valent hydrocarbon group having 1 to 7 carbon atoms; and n and m are each an integer of 1 or 2) ##STR00001##
(in Formula (2), R is (—R.sub.2—(OCO—R.sub.1), and R.sub.1 and R.sub.2 are the same as those in Formula (1)).

A method for the preparation of isocyanates in which: (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.

A method for the preparation of isocyanates in which: (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.

A method for the preparation of isocyanates in which: (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.

A method for preparing an isocyanate in a gaseous phase by feeding, in the presence or absence of an inert gas, an amine-containing gas stream and a phosgene-containing gas stream into a reaction region, allowing the amine and the phosgene to contact in gaseous forms and undergo a phosgenation reaction in the reaction region, thus preparing the target isocyanate in a gaseous form in the reaction region. The phosgene-containing stream is subjected to preheating and warming before being fed into the reaction region, and the phosgene-containing stream comprises a substance A at a mass fraction of <1% before being subjected to the preheating and warming up. Substance A is a NCO group-containing substance and/or an olefinic double bond-containing substance. The method reduces the formation of clogging matter in a heat exchanger and a vessel during the preheating and warming of the phosgene and during the reaction process.

A method for preparing an isocyanate in a gaseous phase by feeding, in the presence or absence of an inert gas, an amine-containing gas stream and a phosgene-containing gas stream into a reaction region, allowing the amine and the phosgene to contact in gaseous forms and undergo a phosgenation reaction in the reaction region, thus preparing the target isocyanate in a gaseous form in the reaction region. The phosgene-containing stream is subjected to preheating and warming before being fed into the reaction region, and the phosgene-containing stream comprises a substance A at a mass fraction of <1% before being subjected to the preheating and warming up. Substance A is a NCO group-containing substance and/or an olefinic double bond-containing substance. The method reduces the formation of clogging matter in a heat exchanger and a vessel during the preheating and warming of the phosgene and during the reaction process.

A composition is provided including a compound (A) represented by Formula (1) and a compound (B) represented by Formula (2), wherein the compound (B) is contained in an amount of 0.00002 to 0.2 parts by mass with respect to 100 parts by mass of the compound (A):

(R.sub.1—COO).sub.n—R.sub.2—(NCO).sub.m   (1)

(in Formula (1), R.sub.1 is an ethylenically unsaturated group having 2 to 7 carbon atoms; R.sub.2 is an (m+n)-valent hydrocarbon group having 1 to 7 carbon atoms; and n and m are each an integer of 1 or 2)

##STR00001##

(in Formula (2), R is (—R.sub.2—(OCO—R.sub.1), and R.sub.1 and R.sub.2 are the same as those in Formula (1)).

A composition is provided including a compound (A) represented by Formula (1) and a compound (B) represented by Formula (2), wherein the compound (B) is contained in an amount of 0.00002 to 0.2 parts by mass with respect to 100 parts by mass of the compound (A):

(R.sub.1—COO).sub.n—R.sub.2—(NCO).sub.m   (1)

(in Formula (1), R.sub.1 is an ethylenically unsaturated group having 2 to 7 carbon atoms; R.sub.2 is an (m+n)-valent hydrocarbon group having 1 to 7 carbon atoms; and n and m are each an integer of 1 or 2)

##STR00001##

(in Formula (2), R is (—R.sub.2—(OCO—R.sub.1), and R.sub.1 and R.sub.2 are the same as those in Formula (1)).

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.