Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D207/00—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom
  • C07D207/02—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
  • C07D207/18—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member
  • C07D207/22—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D207/24—Oxygen or sulfur atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D211/00—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings
  • C07D211/04—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
  • C07D211/68—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member
  • C07D211/72—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member with hetero atoms or with carbon atoms having three bonds to hetero atoms, with at the most one bond to halogen, directly attached to ring carbon atoms
  • C07D211/74—Oxygen atoms
  • C07D211/76—Oxygen atoms attached in position 2 or 6

Definitions

• esterification reactions have typically involved reacting an acid with an alcohol-in the presence of a strong mineral acid, added to promote the reaction.
• a strong acid provides relatively high yields of ester.
• the use of a strong acid medium causes significant difficulties which adversely affect the yields and purities of esters obtained by these processes.
• using a strongly acidic medium should not be considered when either the acid or the ester is prone to acid catalyzed side reactions such as dehydration, isomerization, or hydrolysis.
• the use of a strong acid medium is not appropriate when it is desired to carry out the esterification in reaction vessels which are not specially resistant to the effects of strong acids.
• R is an unsubstituted lower alkyl and m is an integer of from 1 to 3.
• an ester can be readily prepared in high yields and with a high degree of purity under substantially neutral reaction conditions, without the use of highly toxic, explosive and/or unstable alkylating agents.
• This invention relates to a process for preparing an ester by reacting a carboxylic acid with an O-lower alkyl imino ether of formula I.
• n is an integer of from 1 to 4 inclusive and is equal to the valence of R and R is hydrogen, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl or aryl.
• n is an integer of from 1 to 2 and R is unsubstituted alkyl, unsubstituted alkenyl, aryl, aryl lower alkyl or aryl lower alkenyl.
• R is unsubstituted lower alkyl, carboxy lower alkyl, unsubstituted lower alkenyl, unsubstituted aryl, lower alkoxy or hydroxy substituted aryl, unsubstituted aryl lower alkyl, lower alkoxy or hydroxy substituted aryl lower alkyl, unsubstituted aryl lower alkenyl, or lower alkoxy or hydroxy, substituted aryl lower alkenyl.
• alkyl comprehends straight chain and branched chain, saturated aliphatic hydrocarbon groups of l to carbon atoms.
• the alkyl groups of this application may be unsubstituted or substituted with one or more groups such as alkoxy, alkenyloxy, alkynyloxy, hydroxy, oxo, cycloalkyl, cycloalkenyl, cycloalkynyl, cycloalkoxy, cycloalkenyloxy, cycloalkynyloxy and aryl groups.
• the preferred alkyl groups are the unsubstituted lower alkyl groups of l to 6 carbon atoms, such as-methyl, ethyl and isopropyl.
• the particulary preferred alkyl groups are the primary and secondary, unsubstituted, lower alkyl groups, quite particularly methyl and ethyl.
• cycloalkyl comprehends saturated, aliphatic hydrocarbon groupgs of 3 to 20 carbon atoms, containing one or more, saturated, mononuclear or polynuclear, cycloaliphatic moieties, such ascyclopropyl and cyclohexyl.
• alkenyl comprehends straight chain and branched chain, aliphatic hydrocarbon groups of 2 to 20 carbon atoms which contain one or more double bonds.
• the alkenyl groups of this application can be unsubstituted or substituted with one or more groups, such as alkoxy, alkenyloxy, alkynyloxy, hydroxy, oxo, cycloalkyl, cycloalkenyl, cycloalkynyl, cycloalkoxy, cycloalkenyloxy, cycloalkynyloxy and aryl groups.
• the preferred alkenyl groups are the unsubstituted lower alkenyl groups of 2 to 6 carbon atoms such as vinyl and allyl.
• cycloalkenyl comprehends aliphatic hydrocarbon groups of 3 to 20 carbon atoms containing one or more, mononuclear or polynuclear, cycloaliphatic moieties, of 3 to 18 carbon atoms, with at least one of the cycloaliphatic moieties containing one or more double bonds, such as cyclohexenyl.
• alkynyl comprehends straight chain and branched chain, aliphatic hydrocarbon groups of 2 to 20 carbon atoms which contain one or more triple bonds.
• the alkynyl groups of this application can be unsubstituted or substituted with one or more groups, such as alkoxy, alkenyloxy, alkynyloxy, hydroxy, oxo, cycloalkyl, cycloalkenyl, cycloalkynyl, cycloalkoxy, cycloalkenyloxy, cycloalkynyloxy and aryl groups.
• the preferred alkynyl groups are the unsubstituted lower alkynyl groups of 2 to 6 carbon atoms, such as ethynyl and propynyl.
• cycloalkynyl comprehends aliphatic hyrdocarbon groups of 3 to 20 carbon atoms containing one or more, mononuclear or polynuclear, cycloaliphatic moieties,
• cycloaliphatic moieties containing one or more triple bonds, such as cyclohexynyl.
• aryl comprehends mononuclear and polynuclear aromatic hydrocarbon groups such as phenyl, tolyl, etc., which can be unsubstituted or substituted in one or more positions, taken individually or together, with groups such as lower alkylenedioxy, halogen, nitro, alkoxy, alkenyloxy, alkynyloxy, alkyl, alkenyl, alkynyl, cycloalkenyloxy, cycloalkynyloxy, cycloalkyl, cycloalkenyl, cycloalkynyl, hydroxy and 0x0 groups.
• polynuclear aryl groups are groups such as napthyl, anthryl, phenanthyl, azulyl, etc., which may be unsubstituted or substituted with one or more of the aforementioned moieties.
• the preferred aryl groups are the unsubstituted aryl groups and the aryl groups, substituted with a hydroxy or lower alkoxy group, containing 6 to 10 carbon atoms.
• primary alkyl group comprehends groups wherein alkyl is as defined above and wherein the a-carbon atom of the group is a primary carbon atom.
• secondary alkyl group comprehends groups wherein alkyl is as defined above and wherein the a-carbon atom of the group is a secondary carbon atom.
• halogen or halo when not expressly stated otherwise, includes all four halogens, i.e., chlorine, bromine, fluorine and iodine.
• lower alkylenedioxy comprehends groups having 1 to 4 carbon atoms such as methylenedioxy.
• alkoxy, alkenyloxy, a]kynyloxy,cycloalkoxy, cycloalkenyloxy and cycloalkynyloxy comprehends the groups wherein the alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl and cycloalkynyl moieties are as defined above. Still further herein, terms such as aryl lower.
• alkyl, aryl lower alkenyl, and carboxy lower alkyl comprehend alkyl and alkenyl groups which are substi-.
• temperature and pressure are not critical, and the reaction can be conveniently carried out at above about 40C. and at atmospheric pressure.
• the reaction is carried out at a temperature of about 60C. to the reflux temperature of the reaction mixture, with a temperature of about to C. being particularly preferred.
• any carboxylic acid can be utilized, and the ratio of the carboxylic acid to the O-lower alkyl imino ether of formula I is not critical.
• greater amounts of the lower alkyl imino ether canals'o be conveniently utilized.
• This process can, if desired, be carried out in an inert organic solvent.
• any conventional inert organic solvent can be utilized, such as benzene, toluene, methylene chloride or chloroform..
• the inert organic solvent such as benzene, toluene, methylene chloride or chloroform.
• the crude ester was purified by crystallization if the ester was a solid, utilizing an appropriate solvent, or by distillation under reduced pressure if the ester was a liquid to give analytically pure material.
• B.p. l0l-l02/24mm p-Methoxyphenyl acetic acid 80-85 6 76 "B.p. ISO-l l/l 5mm 2-Naphthoic acid 80-85 l6 )6 M.p. 75-76 Adipic acid 80-85 16 72 B.p. 95/9mm Dimethyl acrylic acid 80-85 16 78 B.p. l-l35 Salicylic acid 80-85 16 8O B.p. 87-88/7mm p-Methoxycinnamic acid 80-85 16 73 M.p. 88-90 Residue after diethyl ether removed by distillation. Crystallization not required.
• process of this invention is carried out without utilizing any solvent, using only the carboxylic acid and the 0- alkyl imino ether of formula I.
• a process for preparing an ester comprising: reacting a carboxylic acid with an O-lower alkyl imino ether of the formula:
• R is an unsubstituted lower alkyl and m is an integer of 1 to 3; wherein said carboxylic acid is of the formula:
• n is an integer of from 1 to 4 inclusive and-is equal to the valence of R and R is hydrogen, substituted or unsubstituted alkyl having from 1 to 20 carbon atoms, cycloalkyl having from 3 to 20 carbon atoms, unsubstituted or substituted alkenyl having from 2 to 20 carbon atoms, cycloalkenyl having from 3 to 20 carbon atoms, substituted or unsubstituted alkynyl having from 2 to 20 carbon atoms, cycloalkynyl having from 3 to 20 carbon atoms, unsubstituted or substituted aryl selected from the group consisting of phenyl, naphtyl, anthryl, phenanthyl and azulyl 2.
• the process of claim 1 wherein said process is carried out at about 60C. to the reflux temperature of the reaction mixture.
• n is an integer of from 1 to 2 and R is unsubstituted alkyl, unsubstituted alkenyl, aryl, aryl lower alkyl or aryl lower alkenyl.
• Patent No. 3 875 209 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated Ami] 1 ILQ'ZR ERNEST MOHACSI AND WILLY LEIMGRUBER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

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• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Citations (4)

• 1973
  • 1973-05-03 US US356868A patent/US3875209A/en not_active Expired - Lifetime
• 1974
  • 1974-04-29 IT IT22055/74A patent/IT1010219B/it active
  • 1974-04-30 FR FR7415013A patent/FR2228051B1/fr not_active Expired
  • 1974-04-30 DE DE2421015A patent/DE2421015A1/de active Pending
  • 1974-05-01 JP JP49048385A patent/JPS5025515A/ja active Pending
  • 1974-05-02 GB GB1927074A patent/GB1420302A/en not_active Expired
  • 1974-05-02 NL NL7405905A patent/NL7405905A/xx unknown
  • 1974-05-02 BE BE143839A patent/BE814457A/fr unknown

Patent Citations (4)

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