GB670480A - Improvements in or relating to the process for the production of methyl glucoside - Google Patents

Abstract

Methyl glucoside is obtained by reacting dextrose with methanol in the presence of a sulphonated-type cation exchange material, in the hydrogen state, as catalyst. The proportion of a -glucoside in the product is low and is the same whether a - or b -dextrose or a mixture thereof is used. The starting materials are preferably anhydrous, but up to 5 per cent of water may be present in the reaction mixture. When working continuously, the mother liquor after crystallization of the glucoside should be fractionated to reduce the water-content to 8 per cent or less. The dextrose/methanol ratio may be 1 : 8.5 to 1 : 45 and the catalyst/dextrose ratio may be 1 : 2 to 1 : 8 by weight. The reaction temperature may be 60-100 DEG C. (under pressure if necessary) and the duration 1-48 hours depending on the conditions, until the content of reducing sugar is 4 per cent or less. The cation exchange material may be a sulphonated resin, e.g. of the phenol-formaldehyde or polystyrene type, or a sulphonated carbonaceous material. When the reaction is completed, the catalyst is separated by decantation, filtration or centrifugation and the solution concentrated to crystallization point. For continuous operation, a methanol solution of dextrose containing 20-40 per cent of dextrose by weight, is passed through a bed of catalyst at 200-210 DEG F. at a rate of 0.6-3.6 ml./hour per ml. of catalyst. The dextrose and methanol may be partly reacted before contact with the catalyst bed. Examples are given of batchwise and continuous operation, and flow sheets show preferred methods of operation. According to the Specification as open to inspection under Sect. 91, the process is applicable to the reaction of methanol with other reducing sugars, e.g. arabinose, xylose, galactose, mannose and maltose. It can also be applied to the reaction of dextrose and other reducing sugars with other hydroxy compounds, e.g. ethanol, allyl alcohol, benzyl alcohol, ethylene glycol, ethylene chlorhydrin, propylene glycol, glycerol and hydroxy acids. In the lastnamed case the carboxyl group must be protected. It is also stated that a mixture of sulphonated cation-exchange materials may be used as catalyst. This subject-matter does not appear in the Specification as accepted.ALSO:A catalyst for the production of methyl glucoside from dextrose and methanol comprises a sulphonated-type cation-exchange material in the hydrogen form. This may be a resin, e.g. of the sulphonated phenol-formaldehyde or sulphonated polystyrene type, or else a sulphonated carbonaceous material. The particle size may extend down to 0.35mm. The catalyst is prepared by treatment with a dilute acid to bring it into the hydrogen state, followed by washing with distilled water to pH 4.5-5.0. Finally it is soaked in methanol. An example is given of the preparation of the catalyst and a flow sheet shows the procedure for continuous operation. According to the Specification as open to inspection under Sect. 91, a mixture of sulphonated cation-exchange materials may be used as catalyst, and the process is stated to be applicable to the reaction between dextrose or other reducing sugar and various hydroxy compounds. This subject-matter does not appear in the Specification as accepted.