Patent ID: 7009071

Claim:
A process for preparation of 4-amino-1-hydroxybutylidene-1,1-biphosphonic acid or salts thereof, comprising the steps of: (a) reacting 4-aminobutyric acid with phosphorous acid and phosphorous trichloride in the presence of aralkyl ethoxylates or alkyl ethoxylates, having the formula of R—X—O—(CH 2 CH 2 O) n —H, or in the presence of triglycerides selected from the group consisting of plant oils or animal oils, having the formula of (RCO 2 CH 2 ) 2 CHCOOR, wherein R represents branched or non-branched alkyl groups having 1 to 20 carbon atoms or alkenyl groups having 2 to 20 carbon atoms, n is a number between 1 and 30 and X is a variable which represents phenyl or naphthyl or —CH 2 — when R is an alkenyl group and which represents phenyl or naphthyl when R is an alkyl group; (b) recovering said 4-amino-1-hydroxybutylidene-1,1-biphosphonic acid or salts thereof by an hydrolysis reaction of mono-, di-, tri- or poly phosphorous esters of 4-aminobutyric acid.