CH500228A - Verfahren zur Herstellung von Phosphorsäureestern - Google Patents

Verfahren zur Herstellung von Phosphorsäureestern

Info

Publication number
CH500228A
CH500228A CH836767A CH836767A CH500228A CH 500228 A CH500228 A CH 500228A CH 836767 A CH836767 A CH 836767A CH 836767 A CH836767 A CH 836767A CH 500228 A CH500228 A CH 500228A
Authority
CH
Switzerland
Prior art keywords
preparation
phosphoric acid
acid esters
esters
phosphoric
Prior art date
Application number
CH836767A
Other languages
English (en)
Inventor
Richard Dr Randell Donald
Wilfred Dr Pickles
Original Assignee
Ciba Geigy Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ciba Geigy Ag filed Critical Ciba Geigy Ag
Publication of CH500228A publication Critical patent/CH500228A/de

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10MLUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M1/00Liquid compositions essentially based on mineral lubricating oils or fatty oils; Their use as lubricants
    • C10M1/08Liquid compositions essentially based on mineral lubricating oils or fatty oils; Their use as lubricants with additives
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07FACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F9/00Compounds containing elements of Groups 5 or 15 of the Periodic Table
    • C07F9/02Phosphorus compounds
    • C07F9/06Phosphorus compounds without P—C bonds
    • C07F9/08Esters of oxyacids of phosphorus
    • C07F9/09Esters of phosphoric acids
    • C07F9/12Esters of phosphoric acids with hydroxyaryl compounds
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/49Phosphorus-containing compounds
    • C08K5/51Phosphorus bound to oxygen
    • C08K5/52Phosphorus bound to oxygen only
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00Use of organic ingredients
    • C08K5/49Phosphorus-containing compounds
    • C08K5/51Phosphorus bound to oxygen
    • C08K5/52Phosphorus bound to oxygen only
    • C08K5/521Esters of phosphoric acids, e.g. of H3PO4
    • C08K5/523Esters of phosphoric acids, e.g. of H3PO4 with hydroxyaryl compounds
    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10LFUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L1/00Liquid carbonaceous fuels
    • C10L1/10Liquid carbonaceous fuels containing additives
    • C10L1/14Organic compounds
    • C10L1/26Organic compounds containing phosphorus
    • C10L1/2633Organic compounds containing phosphorus phosphorus bond to oxygen (no P. C. bond)
    • C10L1/2641Organic compounds containing phosphorus phosphorus bond to oxygen (no P. C. bond) oxygen bonds only
    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10MLUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2223/00Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions
    • C10M2223/02Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions having no phosphorus-to-carbon bonds
    • C10M2223/04Phosphate esters
    • C10M2223/041Triaryl phosphates
    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10NINDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00Specified use or application for which the lubricating composition is intended
    • C10N2040/08Hydraulic fluids, e.g. brake-fluids
    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10NINDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2050/00Form in which the lubricant is applied to the material being lubricated
    • C10N2050/015Dispersions of solid lubricants
    • C10N2050/02Dispersions of solid lubricants dissolved or suspended in a carrier which subsequently evaporates to leave a lubricant coating

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Health & Medical Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Polymers & Plastics (AREA)
  • Medicinal Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
  • Fireproofing Substances (AREA)
CH836767A 1966-06-18 1967-06-13 Verfahren zur Herstellung von Phosphorsäureestern CH500228A (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB27316/66A GB1146173A (en) 1966-06-18 1966-06-18 Production of triaryl phosphates

Publications (1)

Publication Number Publication Date
CH500228A true CH500228A (de) 1970-12-15

Family

ID=10257601

Family Applications (1)

Application Number Title Priority Date Filing Date
CH836767A CH500228A (de) 1966-06-18 1967-06-13 Verfahren zur Herstellung von Phosphorsäureestern

Country Status (11)

Country Link
US (1) US3576923A (de)
JP (2) JPS5331863B1 (de)
BE (1) BE700053A (de)
CH (1) CH500228A (de)
CS (1) CS150938B2 (de)
DE (1) DE1618479C3 (de)
ES (1) ES341946A1 (de)
GB (1) GB1146173A (de)
HK (1) HK8777A (de)
NL (1) NL160566C (de)
SE (1) SE343305B (de)

Families Citing this family (81)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4139487A (en) 1965-12-01 1979-02-13 Albright & Wilson Limited Mixed tri-aryl (phenyl and alkylphenyl) phosphate esters
US4093680A (en) * 1966-06-18 1978-06-06 Ciba-Geigy Ag Phosphorylated tertiary butylated phenol/phenol ester reaction mixtures
US4096209A (en) * 1966-06-18 1978-06-20 Ciba-Geigy Ag Phosphorylated secondary butylated phenol/phenol ester mixtures
DE1905095A1 (de) * 1969-02-01 1970-08-13 Dynamit Nobel Ag Verfahren zur Herstellung von Phosphor enthaltenden Verbindungen
GB1414478A (en) * 1972-03-23 1975-11-19 Albright & Wilson Phosphorylation of alkylated phenols
DE2252686C3 (de) * 1972-10-27 1975-09-11 Labofina S.A., Bruessel Polyvinylchloridprä parate
US3859395A (en) * 1973-10-09 1975-01-07 Fmc Corp Triaryl phosphate esters
US3936410A (en) * 1973-10-09 1976-02-03 Fmc Corporation Triaryl phosphate ester plasticizers for polyvinyl chloride compositions
US3931023A (en) * 1974-07-22 1976-01-06 Fmc Corporation Triaryl phosphate ester functional fluids
US3931366A (en) * 1974-12-23 1976-01-06 Stauffer Chemical Company Color improvement of phosphate esters
US4013520A (en) 1975-05-22 1977-03-22 Maxwell Jr Robert W Process for separating 2,6-xylenol from a mixture of cresylic acids
US4315082A (en) * 1978-01-03 1982-02-09 Fmc Corporation Phosphorus compounds
US4246169A (en) * 1978-04-19 1981-01-20 Fmc Corporation Flammable plastics containing a flame retardant amount of polyarylphosphates and the polyarylphosphates
US4207225A (en) * 1979-03-06 1980-06-10 Fmc Corporation Alkoxyalkyl phosphate plasticizing compositions
CA1161456A (en) * 1979-09-17 1984-01-31 Harry H. Beacham Process for the manufacture of mixed phosphoric acid ester compositions
US4378320A (en) * 1979-11-05 1983-03-29 Stauffer Chemical Company Meta-tertiary-butylphenyl diphenyl phosphate
US4351780A (en) * 1980-12-09 1982-09-28 Stauffer Chemical Company Process for preparing isopropylphenyl/phenyl phosphate
US4446265A (en) * 1982-02-01 1984-05-01 Fmc Corporation Flame retardant polyphenylene ether-styrene thermoplastic resin compositions
US4482506A (en) * 1982-10-04 1984-11-13 Fmc Corporation Process for the manufacture of alkyl diaryl phosphate esters
US4443384A (en) * 1982-10-04 1984-04-17 Fmc Corporation Process for the manufacture of mixed phosphoric acid ester compositions
DE3367782D1 (en) * 1982-10-12 1987-01-08 Ciba Geigy Ag Fire-retarding compositions
JPS60164740A (ja) * 1984-02-06 1985-08-27 Japan Synthetic Rubber Co Ltd ポジ型感光性樹脂組成物
US4919833A (en) * 1987-05-21 1990-04-24 Ciba-Geigy Corporation Functional fluids
US4810742A (en) * 1988-02-01 1989-03-07 Occidental Chemical Corporation UV stable, impact resistant, flame retarded ABS composition containing aliphatic resin
GB8823482D0 (en) * 1988-10-06 1988-11-16 Ciba Geigy Ag Flame retardants
US5198483A (en) * 1988-10-06 1993-03-30 Fmc Corporation Flame retardants
US4981615A (en) * 1989-08-21 1991-01-01 Fmc Corporation Process for forming a stable emulsion from a triaryl phosphate reaction mixture residue
JPH0768258B2 (ja) * 1989-12-22 1995-07-26 大八化学工業株式会社 トリス(トリハロネオペンチル)ホスフェートの製造方法
GB9007515D0 (en) * 1990-04-03 1990-05-30 Ciba Geigy Ag Products
JP3199844B2 (ja) * 1991-06-14 2001-08-20 エチル・ペトロリアム・アデイテイブズ・インコーポレーテツド 有機ホスフエート類およびそれらの製造
US6030543A (en) * 1993-03-04 2000-02-29 Great Lakes Chemical Corporation Aircraft hydraulic fluid basestocks
US5630852A (en) * 1994-11-23 1997-05-20 Fmc Corporation Organophosphorus additives for improved fuel lubricity
US6593404B1 (en) 1997-10-23 2003-07-15 Cheil Industries, Inc. Thermoplastic resin composition
US6204257B1 (en) 1998-08-07 2001-03-20 Universtiy Of Kansas Water soluble prodrugs of hindered alcohols
DE69905915T2 (de) * 1998-09-21 2003-11-13 Akzo Nobel N.V., Arnheim/Arnhem Triaryl phosphatesterzusammensetzung
CA2470500C (en) * 2001-12-28 2012-05-15 Guilford Pharmaceuticals, Inc. Aqueous based pharmaceutical formulations of water-soluble prodrugs of propofol
RU2297216C2 (ru) * 2002-04-08 2007-04-20 Эм-Джи-Ай Джи-Пи,Инк. Фармацевтические композиции, содержащие растворимые в воде пролекарства пропофола, и способы их применения
US20040171722A1 (en) * 2003-02-28 2004-09-02 Brown William R. Flame retardant polyurethanes and additive compositions for use in producing them
PL1861458T3 (pl) * 2005-03-21 2010-09-30 Chemtura Corp Opóźniacze płomieni i opóźniające płomień polimery
US8129457B2 (en) 2006-03-22 2012-03-06 Chemtura Corporation Flame retardant blends for flexible polyurethane foam
TW200745148A (en) * 2006-04-24 2007-12-16 Albemarle Corp Low triphenylphosphate, high phosphorous content isopropyl phenyl phosphates with high ortho alkylation
US8834705B2 (en) 2006-06-06 2014-09-16 Exxonmobil Research And Engineering Company Gear oil compositions
US8535514B2 (en) * 2006-06-06 2013-09-17 Exxonmobil Research And Engineering Company High viscosity metallocene catalyst PAO novel base stock lubricant blends
US8921290B2 (en) 2006-06-06 2014-12-30 Exxonmobil Research And Engineering Company Gear oil compositions
US8299007B2 (en) 2006-06-06 2012-10-30 Exxonmobil Research And Engineering Company Base stock lubricant blends
US8501675B2 (en) 2006-06-06 2013-08-06 Exxonmobil Research And Engineering Company High viscosity novel base stock lubricant viscosity blends
US8772210B2 (en) * 2008-03-31 2014-07-08 Exxonmobil Research And Engineering Company High viscosity index PAO with polyurea thickeners in grease compositions
US20090253597A1 (en) * 2008-03-31 2009-10-08 Exxonmobil Research And Engineering Company Lubricant composition with improved varnish deposit resistance
US20090247438A1 (en) * 2008-03-31 2009-10-01 Exxonmobil Research And Engineering Company Hydraulic oil formulation and method to improve seal swell
US8278255B2 (en) * 2008-03-31 2012-10-02 Holt David G L Unexpected shear stability benefits of synthetic oils and viscosity modifier combinations
US8394746B2 (en) * 2008-08-22 2013-03-12 Exxonmobil Research And Engineering Company Low sulfur and low metal additive formulations for high performance industrial oils
US8476205B2 (en) * 2008-10-03 2013-07-02 Exxonmobil Research And Engineering Company Chromium HVI-PAO bi-modal lubricant compositions
US20100105585A1 (en) * 2008-10-28 2010-04-29 Carey James T Low sulfur and ashless formulations for high performance industrial oils
US8716201B2 (en) 2009-10-02 2014-05-06 Exxonmobil Research And Engineering Company Alkylated naphtylene base stock lubricant formulations
US8748362B2 (en) 2010-02-01 2014-06-10 Exxonmobile Research And Engineering Company Method for improving the fuel efficiency of engine oil compositions for large low and medium speed gas engines by reducing the traction coefficient
US8642523B2 (en) * 2010-02-01 2014-02-04 Exxonmobil Research And Engineering Company Method for improving the fuel efficiency of engine oil compositions for large low and medium speed engines by reducing the traction coefficient
US8598103B2 (en) * 2010-02-01 2013-12-03 Exxonmobil Research And Engineering Company Method for improving the fuel efficiency of engine oil compositions for large low, medium and high speed engines by reducing the traction coefficient
US8759267B2 (en) * 2010-02-01 2014-06-24 Exxonmobil Research And Engineering Company Method for improving the fuel efficiency of engine oil compositions for large low and medium speed engines by reducing the traction coefficient
US8728999B2 (en) * 2010-02-01 2014-05-20 Exxonmobil Research And Engineering Company Method for improving the fuel efficiency of engine oil compositions for large low and medium speed engines by reducing the traction coefficient
DE102012200684A1 (de) 2012-01-18 2013-07-18 Leibniz-Institut Für Polymerforschung Dresden E.V. Arylphosphat-PTFE-Dispersion und Verfahren zu ihrer Herstellung
US9359573B2 (en) 2012-08-06 2016-06-07 Exxonmobil Research And Engineering Company Migration of air release in lubricant base stocks
US9458403B2 (en) 2012-09-27 2016-10-04 Exxonmobil Research And Engineering Company High viscosity, functionalized metallocene polyalphaolefin base stocks and processes for preparing same
EP3039103A4 (de) 2013-08-31 2017-06-14 Houghton Technical Corp. Hydraulische flüssigkeitszusammensetzungen
US10689593B2 (en) 2014-08-15 2020-06-23 Exxonmobil Research And Engineering Company Low viscosity lubricating oil compositions for turbomachines
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US11760952B2 (en) 2021-01-12 2023-09-19 Ingevity South Carolina, Llc Lubricant thickener systems from modified tall oil fatty acids, lubricating compositions, and associated methods

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2450903A (en) * 1945-01-17 1948-10-12 Standard Oil Dev Co Phosphorus acid esters of petroleum phenols
GB998310A (en) * 1961-02-27 1965-07-14 Celanese Corp Purification of triaryl phosphates
GB1165700A (en) * 1965-12-01 1969-10-01 Albright & Wilson Triaryl phosphates and resin compositions containing them

Also Published As

Publication number Publication date
DE1618479A1 (de) 1972-03-30
NL160566C (nl) 1983-05-16
NL160566B (nl) 1979-06-15
US3576923A (en) 1971-04-27
SE343305B (sv) 1972-03-06
GB1146173A (en) 1969-03-19
DE1618479B2 (de) 1974-04-11
BE700053A (de) 1967-12-18
HK8777A (en) 1977-02-25
DE1618479C3 (de) 1974-11-21
CS150938B2 (de) 1973-09-17
JPS5110236B1 (de) 1976-04-02
JPS5331863B1 (de) 1978-09-05
ES341946A1 (es) 1968-10-16
NL6708437A (de) 1967-12-19

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