Hals phosphonites as stabilizers

A compound of the formula I ##STR46## in which R.sub.1 and R.sub.2, independently of one another, are hydrogen, C.sub.1 -C.sub.25 alkyl, C.sub.2 -C.sub.24 alkenyl, unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted C.sub.5 -C.sub.8 cycloalkyl;

• unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted phenyl;
• unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted C.sub.5 -C.sub.8 cycloalkenyl;
• C.sub.7 -C.sub.9 phenylalkyl or --CH.sub.2 --S--R.sub.7,
• R.sub.3 is hydrogen or methyl,
• R.sub.4 is hydrogen, C.sub.1 -C.sub.25 alkyl, C.sub.2 -C.sub.24 alkenyl, unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted C.sub.5 -C.sub.8 cycloalkyl;
• unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted phenyl;
• unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted C.sub.5 -C.sub.8 cycloalkenyl;
• C.sub.7 -C.sub.9 phenylalkyl, --CH.sub.2 --S--R.sub.7, --(CH.sub.2).sub.p COOR.sub.8 or --(CH.sub.2).sub.q OR.sub.9,
• R.sub.5 is hydrogen, C.sub.1 -C.sub.8 alkyl, O., OH, NO, --CH.sub.2 CN, C.sub.1 -C.sub.18 alkoxy, C.sub.5 -C.sub.12 cycloalkoxy, C.sub.3 -C.sub.6 alkenyl, C.sub.3 -C.sub.6 alkynyl, C.sub.1 -C.sub.8 acyl, or C.sub.7 -C.sub.9 phenylalkyl which is unsubstituted or substituted on the phenyl ring by C.sub.1 -C.sub.4 alkyl;
• or R.sub.5 furthermore is a radical of the formula II ##STR47## in which R.sub.6 is as defined below for n=1,
• if n is 1,
• R.sub.6 is C.sub.1 -C.sub.25 alkyl, C.sub.2 -C.sub.24 alkenyl, unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted C.sub.5 -C.sub.8 cycloalkyl;
• unsubstituted or C.sub.1 -C.sub.4 alkyl- or phenyl-substituted phenyl;
• unsubstituted or C.sub.1 -C.sub.4 -alkyl-substituted C.sub.5 -C.sub.8 cycloalkenyl;
• or C.sub.7 -C.sub.9 phenylalkyl which is unsubsidized or substituted on the phenyl ring by C.sub.1 -C.sub.4 alkyl;
• if n is 2,
• R.sub.6 is a radical of the formula III ##STR48## R.sub.7 is C.sub.1 -C.sub.18 alkyl, unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted C.sub.5 -C.sub.12 cycloalkyl;
• unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted phenyl;
• C.sub.7 -C.sub.9 phenylalkyl or --(CH.sub.2).sub.r COOR.sub.8,
• R.sub.8 is C.sub.1 -C.sub.18 alkyl, unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted C.sub.5 -C.sub.12 cycloalkyl;
• unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted phenyl;
• or C.sub.7 -C.sub.9 phenylalkyl,
• R.sub.9 is C.sub.1 -C.sub.25 alkyl, unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted phenyl;
• C.sub.7 -C.sub.9 phenylalkyl, C.sub.1 -C.sub.25 alkanoyl, C.sub.3 -C.sub.25 alkenoyl, C.sub.2 -C.sub.25 alkanoyl which is interrupted by oxygen, sulfur or >N--R.sub.11 ;
• C.sub.6 -C.sub.9 cycloalkylcarbonyl, unsubstituted or C.sub.1 -C.sub.12 alkyl-substituted benzoyl;
• thienoyl or furoyl,
• R.sub.10 is C.sub.1 -C.sub.18 alkylene, C.sub.4 -C.sub.18 alkylene which is interrupted by oxygen, sulfur or >N--R.sub.11 ;
• C.sub.4 -C.sub.18 alkenylene, phenylethylene, ##STR49## R.sub.11 is hydrogen or C.sub.1 -C.sub.8 alkyl, R.sub.12 and R.sub.13, independently of one another, are hydrogen, CF.sub.3, C.sub.1 -C.sub.12 alkyl or phenyl or
• R.sub.12 and R.sub.13, together with the carbon atom to which they are bonded, form an unsubstituted or C.sub.1 -C.sub.4 alkyl-substituted C.sub.5 -C.sub.8 cycloalkylidene ring;
• X is a direct bond, oxygen, sulfur or ##STR50## n is 1 or 2, p is 0, 1 or 2,
• q is an integer from 3 to 8, and
• r is 1 or 2.