Process for the preparation of hydroxybiarylphosphines and novel compounds of this group of substances

A hydroxybiarylphosphine of the formula I ##STR16## in which Ar-Ar is biphenyl, 1-phenylnaphthyl or 1,1'-binaphthyl, R.sup.1 and R.sup.2 are identical or different and are F or alkoxy having in each case 1 to 8 carbon atoms or are substituted aryl,

• a and b are identical or different and are an integer from 0 to 4, and the Ar-P and the Ar-O bond are each arranged in the ortho-position to the Ar-Ar bond,
• R.sup.3 and R.sup.4 are identical or different and are alkyl having 1 to 8 carbon atoms, cycloalkyl having 4 to 10 carbon atoms, alkaryl having 7 to 9 carbon atoms, Ar.sup.3 -(R.sup.5).sub.n, in which Ar.sup.3 is an aryl radical having 6 to 10 carbon atoms,
• R.sup.5 is alkoxy having in each case 1 to 8 carbon atoms, CF.sub.3, dialkyl-amino having a total of 2 to 8 carbon atoms or
• --CH.sub.2 N(alkyl).sub.2 having 1 to 3 carbon atoms per alkyl and
• n is an integer from 0 to 5, or --R.sup.3 --R.sup.4 -- forms a chain of 3 to 5 members to which one or two aromatic rings or ring systems having 6 to 10 carbon atoms are optionally fused, and, together with the P atom, forms a ring having 4 to 6 members,
• with the proviso that Ar.sup.3 --(R.sup.5).sub.n is not phenyl or a phenyl substituted by halogen, alkyl or alkoxy each having 1 to 8 carbon atoms, if Ar-Ar is biphenyl or 1,1'-binaphthyl and a.dbd.b.dbd.0 and R.sup.3 and R.sup.4 are identical in each case.