Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/48—Separation; Purification; Stabilisation; Use of additives
  • C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
  • C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
  • C07C69/66—Esters of carboxylic acids having esterified carboxylic groups bound to acyclic carbon atoms and having any of the groups OH, O—metal, —CHO, keto, ether, acyloxy, groups, groups, or in the acid moiety
  • C07C69/67—Esters of carboxylic acids having esterified carboxylic groups bound to acyclic carbon atoms and having any of the groups OH, O—metal, —CHO, keto, ether, acyloxy, groups, groups, or in the acid moiety of saturated acids
  • C07C69/675—Esters of carboxylic acids having esterified carboxylic groups bound to acyclic carbon atoms and having any of the groups OH, O—metal, —CHO, keto, ether, acyloxy, groups, groups, or in the acid moiety of saturated acids of saturated hydroxy-carboxylic acids
  • C07C69/68—Lactic acid esters

Definitions

• the present invention relates to a process for the preparation of ethyl lactate having a purity greater than 97% from lactic acid or a lactic acid composition.
• Ethyl lactate can be used alone or in combination with other solvents, as agents for cleaning and degreasing in a machine and in a non-aqueous medium of solid surfaces such as metal parts, ceramics, glass, materials plastics which have been soiled with oils or greases for machining and / or their temporary protection.
• the present invention therefore relates to a continuous process for preparation of ethyl lactate (I) by esterification 'lactic acid [- or a lactic acid composition] using ethanol according to reaction (1 ):
• this mixture is subjected to a flash separation, at a temperature between 80 ° C and 90 ° C and under a pressure less than or equal to 65 bar, and that, - on the one hand, the flow is subjected overhead comprising ethyl lactate, ethanol and water, to a fractional distillation continuously, at atmospheric pressure, by introducing said flow onto a determined tray of a distillation column;
• the foot flow is continuously recycled, consisting essentially of unprocessed lactic acid and heavy products, in the esterification reaction medium; and recovering, at the top of the fractional distillation, a mixture of ethanol and water, and, at the bottom of the fractional distillation, an ethyl lactate having a water content at most equal to 0.3% , an ethanol content of less than 0.5% and a purity of more than 94%.
• the mixture is extracted from the reaction medium when a conversion rate of lactic acid at most equal to 80% has been reached and, preferably, when this conversion rate is between 65% and 75 %.
• This mixture can be extracted from the reaction medium, agitated by simple overflowing, and then conveyed to a flash separation device.
• the reaction is carried out in the presence of a soluble or insoluble catalyst in the esterification reaction medium.
• soluble catalysts examples include H 2 S0 98%, H 3 P0 4 , methanesulfonic acid. Preferably, H 2 S0 4 98% will be used.
• the catalyst according to the invention is used at molar contents ranging from 0.1% to 4% and, preferably, at contents ranging from 0.2% to 3% relative to the 100% lactic acid used. artwork.
• the overhead stream leaving the flash separation feeds a fractional distillation column at an appropriate location on said column, preferably located in the lower part of said column. This location will be determined by a person skilled in the art by calculation, taking into account in particular the number of theoretical plates of the column, the reflux rate, the desired fractionation.
• the distillation is carried out at atmospheric pressure at a column bottom temperature ranging from 152 ° C to 165 ° C.
• the heads of said distillation comprise ethanol in amounts at most equal to 85% (by weight), water and traces of ethyl lactate.
• This mixture can be dehydrated and the alcohol, in the form of an azeotrope, can be recycled into the esterification reaction medium.
• the process according to the present invention applies very particularly to the esterification with ethanol of the lactic acid contained in commercial lactic acid compositions as defined above.
• lactic acid lactic acid compositions Preferably, 87% by weight lactic acid lactic acid compositions will be used.
• the ethyl lactate from the bottom of the fractional distillation contains almost neither water nor ethanol, which makes it possible to obtain, after easy purification, a pure ethyl lactate.
• the method according to the present invention can be implemented in a device as shown in FIG. 1.
• This device includes:
• a reactor (1) optionally provided with stirring, with a temperature probe, with lactic acid (2), ethanol (3) and catalyst (4) supplies; - a flash separation column (5) supplied in phase extracted from the reactor (1) by the supply line (6);
• the distillation column (7) has a diameter of 70 cm and is filled with a Sulzer B X 70 packing. It has 35 theoretical plates. Conduct of the test
• the ethanol / lactic acid molar ratio is 2.5.
• the esterification is carried out at 80 ° C. under atmospheric pressure.
• the progress of the reaction is carried out by assaying lactic acid by CPV.
• a mixture is continuously extracted from the reactor (1) comprising:
• This mixture is subjected to flash separation in column (5) at 85 ° C under a pressure of 50 m bar.
• the head flow including:
• the operation is carried out at a column bottom temperature of 155 ° C.
• the head temperature is 77.2 ° C.
• the reflux rate is fixed at 1.3.
• a mixture is obtained at the head comprising (by weight) 76% ethanol and 24% water and traces of ethyl lactate ( ⁇ 0.3%).
• the ethyl lactate comes out with a purity greater than 94.6% and containing less than 1% water and less than 1% ethanol.
• This crude ethyl lactate is subjected to purification by fractional distillation under reduced pressure.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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• 2002
  • 2002-12-05 FR FR0215348A patent/FR2848209B1/fr not_active Expired - Fee Related
• 2003
  • 2003-12-05 CN CNA2003801049176A patent/CN1720215A/zh active Pending
  • 2003-12-05 WO PCT/FR2003/003598 patent/WO2004052825A2/fr active Application Filing
  • 2003-12-05 JP JP2004558173A patent/JP2006509024A/ja active Pending
  • 2003-12-05 AU AU2003298421A patent/AU2003298421B2/en not_active Ceased
  • 2003-12-05 BR BR0317047-0A patent/BR0317047A/pt not_active IP Right Cessation
  • 2003-12-05 EP EP03796169A patent/EP1569891A2/fr not_active Withdrawn
  • 2003-12-05 KR KR1020057010224A patent/KR100762773B1/ko not_active IP Right Cessation
  • 2003-12-05 CA CA002508125A patent/CA2508125A1/fr not_active Abandoned
  • 2003-12-05 US US10/537,422 patent/US20060041165A1/en not_active Abandoned
  • 2003-12-05 MX MXPA05005962A patent/MXPA05005962A/es unknown

Non-Patent Citations (1)

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