Abstract: The present invention relates to N-alkyl-N'-poly(oxyalkyl)hexahydropyrimidines of the formula I ##STR1## in which R.sup.1 is C.sub.1 -C.sub.30 -alkyl or C.sub.2 -C.sub.30 -alkenyl,R.sup.2 is hydrogen or C.sub.1 -C.sub.3 -alkyl,A is a 1,2-alkylene group having from 2 to 10, preferably from 2 to 5, carbon atoms andp is a number from 1 to 50.The invention further provides for the use of N-alkyl-N'-poly(oxyalkyl)hexahydropyrimidines of the formula I as corrosion inhibitors in water/oil emulsions as are present in petroleum.

Abstract: The invention relates to alkenylaminoalkane-1,1-diphosphonic acid derivatives of the formula I ##STR1## in which R.sup.1 to R.sup.5, a, b, and Z have the meaning given in the description and to processes for their preparation. The invention furthermore relates to copolymers comprising 0.1-50 mol %, preferably 1-15 mol %, of at least one alkenylaminoalkane-1,1-diphosphonate unit of the formula I and 99.9-50 mol %, preferably 99-85 mol %, of at least one carboxylic acid unit of the formula IIR.sup.6 R.sup.7 C=CR.sup.8 Y (II)in which R.sup.6, R.sup.7, R.sup.8 and Y have the meaning given in the description and to processes for their preparation. These copolymers are used as scale inhibitors, as alkaline earth metal and heavy metal complexing agents and/or sequestering agents and as builders or co-builders in detergents.