Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Patent
1998-04-10
2000-03-14
Geist, Gary
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
560186, 203 2, 203 14, 203 28, C07C 6966, C07C 5146
Patent
active
060374896
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for purifying glyoxylates and a distiller for purification of glyoxylates.
BACKGROUND ART
Glyoxylates are chemical intermediates, for example, monomers suitably used as material for synthesizing sodium polyglyoxylate which is an effective builder component of a surface active agent.
In the case where the glyoxylates to be used as material for forming polymers contain impurities, particularly protic compounds such as water, alcohols, or carboxylic acids, a molecular weight of the resultant polymer tends to decrease. Therefore, when such glyoxylates are used as material for copolymers, the impurities have to be removed from the glyoxylates.
However, since the glyoxylates reversibly combine with water or alcohols in particular thereby forming hydrate, hemiacetal, or the like, to purify the glyoxylates is not easy.
The following purifying methods applicable to the glyoxylates have been proposed:
(1) executing distillation, with phosphoric anhydride added to a material containing glyoxylates;
(2) adding a higher alcohol with a boiling point of not lower than 180.degree. to a material containing glyoxylates, and executing distillation at a pressure not exceeding 800 mmHg (107 kPa) (the Japanese Publication for Laid-Open Patent Application No.62-178541/1987 (Tokukaisho 62-178541));
(3) distilling a mixture containing glyoxylates, glycolates, water, alcohols, and the like under a reduced pressure so that a content of water and alcohols decreases to less than 1 weight percent (wt. %), then, distilling it by adjusting so that a molar ratio of glycolate to glyoxylates becomes 1 to 1.4 (the Japanese Examined Patent Publication No.5-28694/1993 (Tokukohei 5-28694), the Japanese Publication for Laid-Open Patent Application No.60-97936/1985 (Tokukaisho 60-97936));
(4) when glyoxylates are produced from corresponding glycolates by oxidative dehydrogenation in a gaseous phase, adding an azeotropic agent such as methylene chloride, chloroform, n-pentane, cyclohexane, nonane, di-isopropyle ether, methyl ethyl ketone, benzene, toluene, or the like to a gaseous reaction mixture resulting on the oxidative dehydrogenation, and introducing the same to a distillation column (the Japanese Publication for Laid-Open Patent Application No.60-23345/1985 (Tokukaisho 60-23345));
(5) esterifying glyoxylic acid by reacting 1 mol of glyoxylic acid with 0.5 to 2 mol of lower alcohol in the presence of an azeotropic agent such as benzene or dichloroethane, and distilling the same after a concentration of water and alcohol in the reactive solution becomes not more than 10 wt. % each with respect to the resultant glyoxylates (the Japanese Publication for Laid-Open Patent Application No.61-50941/1985 (Tokukaisho 61-50941), the Japanese Examined Patent Publication No.4-66856/1992 (Tokukohei 4-66856)); and
(6) processing a reaction product obtained by oxidative dehydrogenation with respect to glycolates under a reduced pressure, then, supplying the reaction product thus processed to a multi-stage distillation column which holds a dense azeotropic agent such as methylene-dichloride, 1,1,1-trichloroethane, or benzene in the vicinity of its top, so that glyoxylates are taken from an intermediate point between the supplying part and the top part of the distillation column (the Japanese Examined Patent Publication No.7-42252/1995 (Tokukohei 7-42252), the Japanese Publication for Laid-Open Patent Application No.2-73040/1990 (Tokukaihei 2-73040), the Japanese Examined Patent Publication No.7-45435/1995 (Tokukohei 7-45435), the Japanese Publication for Laid-Open Patent Application No.1-254643/1989 (Tokukaihei 1-254643), the Japanese Examined Patent Publication No.5-28694/1993 (Tokukohei 5-28694)).
However, the method (1) is not preferable from an economic viewpoint, since phosphoric anhydride is consumed reacting with water or alcohols and hence it is hardly recovered. The method (2) has a drawback in that side reactions such as ester interexchange and the like may possibly occur. Moreover, sinc
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Cova, D.R. et al, "Distillation of Reactive Methyl Glyoxylate-Methyl Glycolate Mixtures", Separation Science and Technology, 1990, vol. 25, No. 13-15, pp. 1981-1991.
Japanese Examined Patent Publication No. 4-66856/1992 (Tokukohei 4-66856 Published Oct. 26, 1992).
Lide, binary systems, CRC Handbook of Che.& Physics: 6-217, Mar. 1994.
Baba Hideyuki
Miura Satoru
Nonoguchi Masanori
Saito Noboru
Geist Gary
Nippon Shokubai Co. , Ltd.
Oh Taylor V.
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