Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1995-09-25
1998-01-20
Cintins, Marianne M.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568868, 568870, C07C 3118
Patent
active
057103500
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP94/00834, filed on Mar. 16, 1994, published as WO94/21582 Sep. 29, 1994.
FIELD OF THE INVENTION
This invention relates to a process for the production of diglycerol by condensation of glycerol in the presence of a basic catalyst, preferably sodium or potassium hydroxide, at reaction temperatures of 200.degree. to 275.degree. C. and, more particularly, at reaction temperatures of 220.degree. to 240.degree. C. and subsequent concentration of the diglycerol by distillation.
RELATED ART
Diglycerol and higher oligomers of glycerol, such as tri- and tetraglycerol, which are also known generally as polyglycerols, are normally obtained in the alkali-catalyzed condensation of glycerol at elevated temperature. These ethers have relative molecular weights of 166 (6 carbon atoms) to 2,238 (90 carbon atoms) and contain 4 to 32 hydroxyl groups. The polyglycerols are prepared not only by the base-catalyzed dehydration of glycerol, but also by purification of the polyglycerol-containing distillation residue emanating from the synthetic production of glycerol via epichlorohydrin (DE 34 10 520 A1). Their purification is carried out in one or more cation exchangers and an anion exchanger by evaporation of water and vacuum distillation.
For the industrial production of polyglycerol by condensation of glycerol, glycerol is heated together with an alkaline catalyst at a temperature of 200.degree. to 275.degree. C. under normal pressure or reduced pressure. Sodium hydroxide or sodium acetate is normally used as the catalyst. In a typical process, approximately 0.3% of sodium hydroxide is added to glycerol and the reaction mixture is heated to a temperature of around 230.degree. C. at which the water begins to distil off. The mixture is then slowly heated to 260.degree.-265.degree. C. and kept at that temperature until the calculated quantity of water has distilled off. The time required for removal of the water changes slightly with the reaction conditions, although a reaction time of 11 hours for the production of diglycerol is typical. The reaction product obtained contains a number of different polyglycerols and also unreacted glycerol. It is called diglycerol, triglycerol, etc. according to its average composition which is characterized by the hydroxyl value or the quantity of water distilled off (book: Miner and Dalton, Glycerol, Reinhold Publ. Corp. New York 1953, pages 366 to 368).
It is also known that the polyglycerols present in the reaction mixture can be separated by acetylation and distillation of the acetates. Another method of separating the polyglycerols comprises distilling their allyl ethers or their isopropylidene derivatives. The polyglycerols are obtained by hydrolysis. It is also known that the lower polyglycerols can be directly separated by distillation providing a sufficiently low pressure (vacuum) is applied.
Subsequent separation of the reaction mixture into the individual polyglycerols is not possible in the production of diglycerol by autocondensation of glycerol. Although there is no need for subsequent separation in certain known production processes (G. Jakobson, Fette-Seifen-Anstrichmittel 3(88) 1986, pages 101 to 106) these processes are attended by the disadvantage that either the starting substances are difficult to obtain or the synthesis involves several intermediate stages.
In another known process for the production of polyglycerols by autocondensation of glycerol, glycerol is condensed in the presence of lithium hydroxide at temperatures of 200.degree. to 300.degree. C. and, more particularly, at 260.degree. C. The water of reaction is continuously distilled. Where a high glycerol content is required, the condensation reaction is terminated when the quantity of water theoretically required for the formation of diglycerol has been separated. The diglycerol may then be separated from the oligoglycerol mixture formed by distillation in a high vacuum (DE 41 24 665 A1).
The polyglycerols, including in particular diglycerol, are used as starting material
REFERENCES:
patent: 2487208 (1949-11-01), Alsop
Minner et al., Glycerol, Reinhold publ. Corp., New York 1953, pp. 366 to 368.
Chemical Abstracts, vol. 98, no 21, 23 May 1983, abstract no. 178739j, "Diglycerol Purification", p. 600.
Chemical Abstracts, vol. 113, No. 15, 8 Oct. 1990, Colombus, Ohio, US; abstract No. 132708y, I. Naribayasi et al'Preparation of High-Purity Diglycerin, p 708 ; col. 1 ; & JP ,A,02 169 536 (Sakamoto Yakuhin).
Chemical Abstracts, vol. 98, No. 21, 23 May 1983, Columbus, Ohio, US; abstract No. 178739j, `Diglycerol Purification`, p. 600 ;col. 1; see abstract & JP ,A,57 203 023 (Daicel Chemical Industries).
Milner and Dalton, Glycerol, Reinhold Publ. Corp. New York 1953, pp. 366 to 368.
G. Jakobson, Fette-Seifen-Anstrichmittel 3(88) 1986, pp. 101 to 106.
Bunte Reinhard
Gutsche Bernhard
Jeromin Lutz
Jordan Volkmar
Cintins Marianne M.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Jones Dwayne C.
Ortiz Daniel S.
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