# US 5,710,305 A · Flame retardant product and process > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,710,305 A - Document ID: US5710305A - Status: Granted - Kind: A - Application number: 08/691,119 - Filed: 1996-08-01 - Granted: 1998-01-20 - Earliest claimed: 1995-08-16 - Assignees: Albright & Wilson UK Limited - Inventors: Adrian Charles Archer; Christopher John Harris; Gary Woodward; Mohsen Zakikhani - Web page: https://patentgrep.com/patent/US5710305A ## CPC - C07F 9/65742: {non-condensed with carbocyclic rings or heterocyclic rings or ring systems} - C07F 9/657181: {the ring phosphorus atom and, at least, one ring oxygen atom being part of a (thio)phosphonic acid derivative} - C07F 9/65746: {the molecule containing more than one cyclic phosphorus atom} - C08K 5/5357: cyclic - H05K 1/0373: {containing additives, e.g. fillers (H05K1/036 takes precedence)} - C07F: ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM (metal-containing porphyrins C07D487/22) - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract A method for producing alkyl derivatives of phosphonic acids together with hexyl-bis›5-ethyl-2-hexyl-1,3,2-dioxaphosphorinan-5-yl)methyl!ester, P,P'dioxide as a novel product and the use of such a product as, or in connection with, a flame retardant. ## Claims ### Claim 1 A method of producing a flame retardant of general formula (I): ##STR7## in which R is independently selected from the group consisting of linear, branched or cyclic alkyl, alkenyl, and provided that R bonded to the cyclic phosphorus atom is not alkoxy, alkoxyl, R' is selected from the group consisting of linear, branched or cyclic alkyl, alkenyl, alkaryl, aryl, aralkyl, haloaryl, aryloxyalkyl, haloaryloxyalkyl, and hydroxyalkyl, m is 0, 1 or 2, n is 1, 2 or 3 and (n+m) is 3 wherein said method comprises a first step and a second step, and optionally a third step, said first step comprising: (a) reacting a bicyclic phosphite of general formula (II): ##STR8## wherein said R' is as hereinabove defined, with an acid selected from the group consisting of phosphorous acid, phosphoric acid, hypophosphorous acid, phosphonic acid and derivatives or salts thereof, in a molar ratio sufficient to produce a phosphite of general formula (III): ##STR9## wherein said R', n and m are as hereinabove defined, and each X is independently selected from the group consisting of H, OH, alkyl, alkenyl, and alkoxy, and mixtures thereof and said second step comprising: (b) reacting said phosphite (III) with an alkene or alkyne selected from the group consisting of linear, branched or cyclic alkenes or alkynes, and substituted alkenes or alkynes which have at least one .alpha.-unsaturated bond, in the presence of a free radical initiator to produce said flame retardant of general formula (I) and said optional third step comprising: (c) purifying said flame retardant. ### Claim 2 (depends on 1) The method of claim 1, in which each said R group is independently selected from the group consisting of C.sub.2 to C.sub.22 alkyl, alkenyl, and alkoxy. ### Claim 3 (depends on 1) The method of claim 1, in which said R' group is selected from the group consisting of C.sub.1 to C.sub.6 alkyl, alkenyl, and alkoxy. ### Claim 4 (depends on 1) The method of claim 1, in which each said R group is independently selected from the group consisting of C.sub.2 to C.sub.12 alkyls and said R' is C.sub.2 alkyl. ### Claim 5 (depends on 1) The method of claim 1, in which said acid is selected from the group consisting of C.sub.1 to C.sub.22 alkyl phosphonic acids and dialkyl phosphinic acids. ### Claim 6 (depends on 1) The method of claim 1 in which said acid is a monoalkyl alkyl phosphonate. ### Claim 7 (depends on 6) The method of claim 6 in which said monoalkyl alkyl phosphonate is monobutyl butyl phosphonate. ### Claim 8 (depends on 1) The method of claim 1, in which said molar ratio of the bicyclic phosphite (II) to the number of free acid groups of said acid is within the range of 1.2:1 to 1:1.5. ### Claim 9 (depends on 1) The method of claim 1, in which the reaction of said bicyclic phosphite (II) and said acid is carried out at 90.degree. C. to 180.degree. C. for 0.5 to 10 hours. ### Claim 10 (depends on 1) The method of claim 1, in which said alkene is selected from the group consisting of C.sub.2 to C.sub.22 alkenes. ### Claim 11 (depends on 10) The method of claim 10, in which said C.sub.2 to C.sub.22 alkene has one or more further unsaturated bonds. ### Claim 12 (depends on 1) The method of claim 1, in which the molar ratio of said phosphite (III) to said alkene or alkyne or substituted alkene or alkyne is within the range 1:0.7 to 1:5. ### Claim 13 (depends on 1) The method of claim 1, in which said alkyne is acetylene. ### Claim 14 (depends on 1) The method of claim 1, in which said free radical initiator is selected from the group consisting of peroxides and azobisisobutylnitriles. ### Claim 15 (depends on 14) The method of claim 14, in which said free radical initiator is present in an amount of up to 10 mole %, based on the amount of said alkene, or alkyne or substituted alkene or alkyne. ### Claim 16 (depends on 1) The method of claim 1, in which said free radical initiator consists of a non-chemical source selected from UV radiation, ionising radiation and ultra sound radiation. ### Claim 17 (depends on 1) The method of claim 1, wherein the reaction of said phosphite (III) with said alkene or alkyne or substituted alkene or alkyne is carried out over 1 to 50 hours at 100.degree.-200.degree. C. ### Claim 18 (depends on 1) The method of claim 1, wherein said optional third step (c) consists essentially of purifying said flame retardant (I) by means of adding an alkyl halide. ### Claim 19 (depends on 18) The method of claim 18, wherein said alkyl halide is present in an amount of up to 5 mole % based on the amount of said bicyclic phosphite (II). ### Claim 20 (depends on 18) The method of claim 18, in which said alkyl halide is a butyl bromide. ### Claim 21 (depends on 18) The method of claim 18, in which said flame retardant (I) is purified at a temperature of 100.degree. C. to 200.degree. C. for 1 to 15 hours.