Process for producing end-group-locked non-ionic tensides

Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing

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568616, 568617, 252351, 252329, C07C 4311

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active

060282290

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to a process for the production of end-capped nonionic surfactants by direct etherification of fatty alcohol polyglycol ethers with dialkyl sulfates in the presence of solid bases and hydrides and addition of water for phase separation.
2. Discussion of Related Art


PRIOR ART

In a number of industrial processes, the presence of foam is extremely undesirable. For example, both in the machine washing of beer bottles or milk bottles and in the spray cleaning of automobile panels, not only is the cleaning or degreasing effect of the surface-active formulations used an important factor, the avoidance of foam which can seriously interfere with the operation of machinery is of equal importance--all the more so insofar as highly active, but also high-foaming anionic surfactants are often used.
The problem of controlling foam has been known for some time. Accordingly, various more or less convincing solutions are known from the prior art and may be divided into two groups:
The first group comprises processes involving the addition of defoamers which are often paraffinic hydrocarbons or silicone compounds. So far as the described applications are concerned, however, this is undesirable in most cases. The second group of processes involves the use of surface-active formulations which are themselves low-foaming and which, optionally, may also exhibit defoaming properties. The formulations in question are generally nonionic surfactants or surfactant-like systems such as, for example, fatty alcohol propylene glycol ethers or block polymers of ethylene and propylene glycol which, unfortunately, are not sufficiently biodegradable.
End-capped fatty alcohol polyglycol ethers, so-called "mixed ethers", which are described for example by R. Piorr in Fat. Sci. Technol. 89, 106 (1987), have established that themselves on the market as particularly effective low-foaming surfactants. These products are generally butyl-end-capped nonionic surfactants which are known, for example, from EP-A 0 124 815, EP-B 0 303 928, EP-B 0 324 340, EP-A 0 420 802, DE-A 3 928 600 and DE-C 4 243 643.
Methyl mixed ethers occupy a special position. They are methyl-end-capped and are normally prepared by reaction of the corresponding fatty alcohol polyglycol ethers with methyl halides [U.S. Pat. No. 4,587,365, BASF] or dimethyl sulfate.
In this connection, EP 0 302 487 B1 (BASF) describes a one-pot process for the production of end-capped nonionic surfactants in which fatty alcohol polyglycol ethers are reacted with dialkyl sulfates in the presence of aqueous alkali metal hydroxides, the reaction taking place at a temperature of 20 to 60.degree. C. and the concentration of alkali metal hydroxide having to be kept at or above 35% by weight, based on the aqueous phase, throughout the reaction. However, the products contain up to 25% by weight of unreacted starting product and are unacceptable from the point of view of color.
Accordingly, the problem addressed by the present invention was to provide an improved process for the production of end-capped nonionic surfactants of the methyl mixed ether type which would be distinguished by a reduced content of unreacted starting material and by improved color quality.


DESCRIPTION OF THE INVENTION

The present invention relates to a process for the production of end-capped nonionic surfactants corresponding to formula (I): ##STR3## in which R.sup.1 is an alkyl and/or alkenyl group containing 6 to 22 carbon atoms, and ##STR4## in which R.sup.1, n1, n2 and m are as defined above, are etherified with dialkyl sulfates (IV) in the presence of solid substantially water-free bases (III) and alkali metal and/or alkaline earth metal hydrides, separation occurs and
A process in which alcoholate formation and etherification are carried out in the presence of aqueous bases is already known from the prior art. Surprisingly, it has been found to be of far greater advantage to carry out the "one-pot reaction", i.e. formation of the alcoholate and

REFERENCES:
patent: 4548729 (1985-10-01), Schmid et al.
patent: 4587365 (1986-05-01), Archor
patent: 4922029 (1990-05-01), Birnbach et al.
patent: 4942049 (1990-07-01), Schmid et al.
patent: 4973423 (1990-11-01), Geke et al.
patent: 5484553 (1996-01-01), Guth et al.
Fat. Sci. Technol., 89(3):106-11 (1987).

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