Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Patent
1992-03-30
1993-06-29
Prescott, Arthur C.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
562523, 562538, 562421, 252 891, 252142, C07C 6700
Patent
active
052236420
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a process for the preparation of ether carboxylic acids by ethoxylation of carbohydrates, followed by catalytic oxidation, and to the use of the products obtained.
Owing to their eutrophying effect in lakes and rivers, the use of phosphates in detergents and cleaning agents has become restricted by law and in some cases even prohibited in a number of countries. As a result, a large number of substitutes for phosphates, in particular for sodium tripolyphosphate, have been developed and proposed in the meantime as builder. However, the desirable properties of sodium tripolyphosphate in its application as a detergent have hitherto not been achieved entirely by any single substance. Rather, only combinations of builders are capable of achieving in a first approximation the effect of phosphates. Only a relatively small number of phosphate substitutes, or rather partial substitutes, are fully satisfactory with respect to their ecological properties. Although they do not promote eutrophication of lakes and rivers, they have nevertheless in some cases properties which must be regarded as questionable in their effect on the environment, such as remobilization of heavy metals from sediments of the lakes and rivers or insufficient biological degradability; therefore, their effect on the environment is uncertain, even if these substances do not immediately have to be considered toxic according to current knowledge. Accordingly, the search for effective builders for detergents which can be considered safe with respect to their ecological effect continues.
In JP-A2-58/117,284 so-called viscosity-reducing agents of coal sludges are disclosed, which can be prepared by reaction of polyhydric alcohols, which also include carbohydrates, with alkylene oxides to give polyether compounds, followed, if desired, by conversion of the terminal hydroxyl groups into carboxyl groups; however, more detailed information on the synthesis of these products is not given.
Ethoxylation of carbohydrates has been known for quite a long time. Thus, for example, W. Gerhardt, J. f. prakt. Chem., 4th series, 29, 300 (1965) has described ethoxylation of saccharose; JP-A2-58/117,284 also mentions further carbohydrates. However, economical processes for the preparation of oxidized ethoxylates of carbohydrates and the use of such products as builders are hitherto not known.
Accordingly, the object was to develop biologically degradable phosphate substitutes and an economical and industrially feasible method of preparation.
Surprisingly, it has now been found that biologically degradable phosphate substitutes having good lime-binding power are obtained by ethoxylating carbohydrates, followed, if desired, by alkoxylation by means of a higher alkylene oxide, and converting the terminal primary hydroxyl groups into carboxyl groups by catalytic oxidation.
Accordingly, the invention relates to a process for the preparation of ether carboxylic acids by alkoxylation of carbohydrates and derivatives thereof, followed by oxidation, which process comprises either ethoxylating the carbohydrates or derivatives thereof directly in the usual manner or first alkoxylating them using a higher alkylene oxide and then ethoxylating them and oxidizing the aqueous solution thus obtained without any further treatment in a pH range in which the carbohydrates and carboxylic acids derived therefrom are stable, using oxygen as the oxidizing agent in the presence of a catalyst containing at least one platinum metal.
The invention furthermore also relates to the use of these ether carboxylic acids in particular as additive (builder) in detergents or cleaning agents.
The ether carboxylic acids prepared by the process according to the invention are suitable in particular as builders in detergents and cleaning agents, due to their surprisingly high lime-binding power.
Suitable starting materials are virtually any carbohydrates having at least one alkoxylatable hydroxyl group and one alcohol group which can be oxidized to a carboxyl group,
REFERENCES:
patent: 3799977 (1974-03-01), Rutledge
patent: 4082788 (1978-04-01), Mims
patent: 4214101 (1990-07-01), Miya et al.
patent: 4952721 (1990-08-01), Fjare
Sanyo Kasei Kogyo K.K., Pat. Abs. of Japan 6: No. 131, Abstract of JP 57-58642 (Apr. 8, 1992).
Hoechst Aktiengesellschaft
Prescott Arthur C.
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