Hydroquinones

Hydroquinone compounds having the formula:

• ##STR14## wherein p is 1 or 2 and q is 0 or 1, provided that p+q is 1 or 2;
• R is a residue of formula:
• ##STR15## wherein Q is selected from the residues:
• --COZR.sub.4 wherein Z is O or NR.sub.5, and R.sub.4 independently is H, a straight or branched chain alkyl having from 1 to 20 carbon atoms, optionally interrupted by 1 to five oxygen atoms, and optionally substituted by a group OR.sub.6 wherein R.sub.6 is C.sub.1 -C.sub.12 alkyl, C.sub.3 -C.sub.12 cycloalkyl, straight or branch C.sub.3 -C.sub.20 alkenyl, C.sub.6 -C.sub.10 aryl or C.sub.7 -C.sub.13 aralkyl, or R.sub.4 is a straight or branched chain alkenyl group having from 3 to 20 carbon atoms, a cycloalkyl group having from 3 to 12 carbon atoms, an aryl group having from 6 to 10 carbon atoms optionally substituted by a C.sub.1 -C.sub.4 alkyl group;
• or an aralkyl group having from 7 to 13 carbon atoms, a 5- or 6-membered heterocycle containing an oxygen atom and optionally substituted by one or two C.sub.1 -C.sub.4 straight- or branch chain alkyl groups;
• or methyl substituted by a 5- or 6-membered heterocycle containing an oxygen atom and optionally substituted by one or two C.sub.1 -C.sub.4 straight- or branch chain alkyl groups;
• and when Z is --NR.sub.5, R.sub.5 is hydrogen or a straight or branched chain alkyl group having from 1 to 20 carbon atoms, or R.sub.4 and R.sub.5 together with the nitrogen atom to which they are each bonded may form a 5- or 6-membered heterocyclic ring, optionally substituted by one or two C.sub.1 -C.sub.4 alkyl groups;
• n is an integer from 1 to 20;
• k is 1 or 2;
• R.sub.2 and R.sub.3 are the same or different and each is straight or branched chain alkyl group having from 1 to 5 carbon atoms and, when Q is CO.sub.2 R.sub.4, either R.sub.2 or R.sub.3 is optionally substituted by a --CO.sub.2 R.sub.4 group, the R.sub.4 groups being independent, or R.sub.2 and R.sub.3 may be so linked to the residue C.sub.n H.sub.2n+1-k that there is formed a C.sub.5 -C.sub.12 cycloalkylene residue substituted by the group --(CO.sub.2 R.sub.4).sub.k, the R.sub.4 groups being independent, wherein R.sub.4 and k have their previous significance, R.sub.1 is C.sub.1 -C.sub.8 straight or branched chain alkyl, or a residue of formula II as hereinbefore defined, and when R.sub.1 is a residue of formula II, then R.sub.1 and R may be the same or different;
• and salts thereof with organic or inorganic acids and bases.