Substituteed tetrahydropyrimidine derivatives and their use as polymerization inhibitors for vinyl aromatic compounds

A vinyl containing composition comprising at least one vinyl group containing compound and a polymerization inhibitory effective amount of at least one substituted tetrahydro-pyrimidine derivative of the general formula ##STR7## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, and R.sup.7, which may be the same or different, are hydrogen or alkyl, aryl, cycloalkyl, alkaryl, aralkyl, or substituted derivative thereof, R.sup.6 or R.sup.7 can additionally be --OH or --NR.sup.8 wherein R.sup.8 is hydrogen, alkyl, aryl, cycloalkyl, alkaryl or aralkyl, or substituted derivative thereof, and X is oxyl or hydroxy, it being provided that at least one of R.sup.2 and R.sup.3 and at least one of R.sup.4 and R.sup.5 are other than hydrogen.

A stabilized composition comprising at least one polymer which is susceptible to degradation and in need of stabilization to prevent or inhibit such degradation and a stabilizing effective amount of at least one substituted tetrahydropyrimidine derivative of the general formula ##STR8## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, and R.sup.7, which may be the same or different, are hydrogen or alkyl, aryl, cycloalkyl, alkaryl, aralkyl, or substituted derivative thereof, R.sup.6 or R.sup.7 can additionally be --OH or --NR.sup.8 wherein R.sup.8 is hydrogen, alkyl, aryl, cycloalkyl, alkaryl or aralkyl, or substituted derivative thereof, it being provided that at least one of R.sup.2 and R.sup.3 and at least one of R.sup.4 and R.sup.5 are other than hydrogen.

A method for inhibiting the polymerization of a vinyl aromatic compound which comprises adding thereto a polymerization inhibiting amount of at least one substituted tetrahydropyrimidine derivative of the general formula ##STR9## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, and R.sup.7, which may be the same or different, are hydrogen or alkyl, aryl, cycloalkyl, alkaryl, aralkyl, or substituted derivative thereof, R.sup.6 or R.sup.7 can additionally be --OH or --NR.sup.8 wherein R.sup.8 is hydrogen, alkyl, aryl, cycloalkyl, alkaryl or aralkyl, or substituted derivative thereof, and X is oxyl or hydroxy, it being provided that it least one of R.sup.2 and R.sup.3 and at least one of R.sup.4 and R.sup.5 are other than hydrogen.

A method for stabilizing at least one polymer which is susceptible to degradation and in need of stabilization to prevent or inhibit such degradation which comprises adding thereto a stabilizing effective amount of at least one substituted tetrahydropyrimidine derivative of the general formula ##STR10## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, and R.sup.7, which may be the same or different, are hydrogen or alkyl, aryl, cycloalkyl, alkaryl, aralkyl, or substituted derivative thereof, R.sup.6 or R.sup.7 can additionally be --OH or --NR.sup.8 wherein R.sup.8 is hydrogen, alkyl, aryl, cycloalkyl, alkaryl or aralkyl, or substituted derivative thereof, it being provided that at least one of R.sup.2 and R.sup.3 and at least one of R.sup.4 and R.sup.5 are other than hydrogen.