A method for the manufacture of compounds containing an α-oxy phosphorus group having the formula: R 3 [-O-C(R 1)(R 2) m (P R a R b) 2-m] n -III- comprising the steps of reacting a compound containing an α-oxy-carboxylic acid group selected from: glycolic acid; diglycolic acid; lactic acid; methoxyacetic acid; sodium methoxyacetate; butoxyacetic acid; 3,6-dioxaheptanoic acid; 3,6,9-trioxadecanoic acid; 3,6-dioxadodecanoic acid; 3,6,9-trioxaundecane-1,11-dioic acid; 5-chloro-3-oxapentanoic acid; 5-amino-3-oxapentanoic acid; 5-phthalimido-3-oxapentanoic acid; 2-tetrahydrofuroic acid; methoxy-phenyl-acetic acid; 2-methoxy-butane-1,4-dioic acid; potassium trans-phenylglycidate; 2-allyloxy-propionic acid; 2,2,2-trifluoroethoxyacetic acid; and a P-O component having at least one P-O-P moiety, whereby at least one phosphorus has the +3 oxidation state, whereby the second phosphorus of the P-O-P moiety in the P-O component has a +3 or +5 oxidation state, and whereby at least 20 mol% of the total P atoms in the P-O component are at the +3 oxidation state, by adding the P-O component to the compound containing an α-oxy carboxylic acid group, or the reverse, in an equivalent ratio of α-oxy carboxylic acid functions in the compound containing an α-oxy carboxylic acid group: P -O-P(III,V) moieties in the P-O component of from 1: 6 to 2: 1; wherein R a and R b are independently selected from a C 1-20 hydrocarbon chain in branched or linear configuration; a silyl group independently substituted by C 1-20 hydrocarbon groups in branched, linear, cyclic or aromatic configuration; or OR" or N(R") 2 wherein R" can be selected from a C 1-20 hydrocarbon chain in branched or linear configuration or a silyl group independently substituted by C 1-20 hydrocarbon groups in branched, linear, cyclic or aromatic configuration; if R a or R b is a N(R") 2 group, then the two R" groups can be connected together with one R" group being a C 1-20 hydrocarbon chain in branched or linear configuration and the other R" being a direct bond; R a and R b can be connected, then R a is a C 1-20 hydrocarbon chain in branched or linear configuration and R b is a direct bond; if R a and R b are OR" groups, then R" of the first OR" group can be a C 1-20 hydrocarbon chain in branched or linear configuration and the R" of the second OR" group a direct bond; if R a and R b are N(R") 2 groups, then one R" group of the first N(R") 2 group can be a C 1-20 hydrocarbon chain in branched or linear configuration and one R" of the second N(R") 2 group is a direct bond to the R"-group of the first N(R") 2 group; or R a and/or R b are OM'; m and n can be 1; M' is represented by H or alkaline, earth alkaline, ammonium or protonated amine species; R 1 is selected from: H, methyl, phenyl, or linked to R 3 to form a OC 2 or OC 4 ring; R 2 is H; R 3 is selected from H, optionally substituted alkyl, or is linked to R 1. glycolic acid; diglycolic acid; lactic acid; methoxyacetic acid; sodium methoxyacetate; butoxyacetic acid; 3,6-dioxaheptanoic acid; 3,6,9-trioxadecanoic acid; 3,6-dioxadodecanoic acid; 3,6,9-trioxaundecane-1,11-dioic acid; 5-chloro-3-oxapentanoic acid; 5-amino-3-oxapentanoic acid; 5-phthalimido-3-oxapentanoic acid; 2-tetrahydrofuroic acid; methoxy-phenyl-acetic acid; 2-methoxy-butane-1,4-dioic acid; potassium trans-phenylglycidate; 2-allyloxy-propionic acid; 2,2,2-trifluoroethoxyacetic acid; R 1 is selected from: H, methyl, phenyl, or linked to R 3 to form a OC 2 or OC 4 ring; R 2 is H; R 3 is selected from H, optionally substituted alkyl, or is linked to R 1.