Organic compounds -- part of the class 532-570 series – Organic compounds – Phosphorus esters
Patent
1997-10-24
1998-10-13
Ambrose, Michael G.
Organic compounds -- part of the class 532-570 series
Organic compounds
Phosphorus esters
562 23, C07F 96574, C07F 930
Patent
active
058213767
DESCRIPTION:
BRIEF SUMMARY
This application was filed under 35 U.S.C. 371 and is the National Stage of International Application No. PCT/EP96/02715, filed Jun. 21, 1996.
The tautomeric compounds (6H)-dibenzo-(c,e)(1,2)-oxaphosphorin-6-one (=9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), usually referred to as "DOP" in the field, and 6-hydroxy-(6H)-dibenzo-(c,e)(1,2)-oxaphosphorine are known compounds, the reaction products of which with itaconic acid, itaconic acid ester or itaconic acid anhydride are widely used as copolycondensable flameproofing agents for polyester fibres. Copolycondensable flameproofing agents for polyester fibres are incorporated directly into the polyester chain during the polymerisation of the polyester and thereby become an integral constituent of the polyester chain. The flameproofing agents fixedly incorporated into the polyester fibres are by nature far superior to those flameproofing agents with which polyester fibres are subsequently finished. The preparation of the said DOP/itaconic acid derivatives and the use thereof is described in German patent specification no. 26 46 218, for example.
German patent no. 20 34 887 discloses a process for the preparation of DOP and the preparation of 2'-hydroxydiphenyl-2-phosphinic acid, a hydrolysis product of DOP, wherein o-phenylphenol is reacted under reflux with phosphorus trichloride in the presence of a Lewis acid as a catalyst, with the release of hydrogen chloride, and the resulting reaction mixtures are hydrolysed, after which crystalline products are ultimately obtained. However, none of the modifications of the process disclosed in the named patent was satisfactory for the preparation of DOP on a commercial scale, in particular for reasons of safety in the workplace, environmental protection and the cost of the apparatus needed to carry out the process.
In a modification of the known process (example 1), phosphorus trichloride and o-phenylphenol are gradually heated to 140.degree. C. in a first step. After the release of hydrogen chloride is complete, zinc chloride is added as a catalyst, and one gradually heats to 210.degree. C. in a second step. The reaction product must then be high-vacuum distilled (195.degree. C., 20 torr) in a third step. Therefore, for production on a commercial scale, the entire production plant must meet the prescribed safety requirements for high-vacuum operation.
In another modification of the known process (examples 2 and 3), the first step of the process is carried out as a one-pot reaction; in the second step, however, an excess of phosphorus trichloride must then subsequently be added over a period of 15 hours, which is associated with considerable safety-related expenditure on account of the harmfulness of this chemical. After that, the mixture must be heated to 200.degree. C. to 230.degree. C. and then be high-vacuum distilled.
Hydrolysis of the initially formed 6-chloro-(6H)-dibenzo-(c,e)(1,2)-oxaphosphorine is carried out by the known method either by pouring the oily residue from high-vacuum distillation directly onto ice or into a sodium carbonate solution, to which activated carbon has been added. Both hydrolysis variations are unsatisfactory, with respect to both the yield and the necessary finishing steps (recrystallisation, filtration).
European patent application EP-A-0 582 957 discloses a process for the preparation of 6-chloro-(6H)-dibenzo-(c,e)(1,2)-oxaphosphorine, wherein o-phenylphenol and the catalyst are heated to 180.degree. C. while being stirred. The phosphorus trichloride is then charged to the mixture at a temperature between 170.degree. C. and 220.degree. C. within 8 to 20 hours. The resulting crude product can be directly further processed, e.g. as a 50% solution in toluene or xylene.
However, as phosphorus trichloride is generally used in excess to optimise yields, vacuum distillation (165.degree. C., 0.17 kPa) also has to be carried out in this known process.
The object of the invention is to improve a process for the preparation of 2'-hydroxydiphenyl-2-phosphinic acid in the form of a comme
REFERENCES:
patent: 3702878 (1972-11-01), Saito
patent: 5391798 (1995-02-01), Kleiner
patent: 5481017 (1996-01-01), Kleiner
Haruna et al, "Preparation of Novel Cyclic Phosphonites" Chemical Abstracts, vol. 121, No. 21, 21 Nov. 1994, Abstract No. 246037.
Dietrich Jorg
Rathfelder Paul
Rieckert Horst
Ambrose Michael G.
Schill & Seilacher (GmbH & Co.)
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