Process for the production of substantially odorless fatty alcoh

Details Process for the production of substantially odorless fatty alcoh Process for the production of substantially odorless fatty alcoh

1994-11-30

1996-10-15

Chan, Nicky

Organic compounds -- part of the class 532-570 series

Organic compounds

Sulfate esters

558 31, C07C30510

Patent

active

055655980

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/EP93/01300 filed May 24, 1993.


FIELD OF THE INVENTION

This invention relates to a process for the production of substantially odorless fatty alcohol ethersulfate salts in which selected fatty alcohol cuts are ethoxylated, sulfated and then neutralized.


PRIOR ART

Anionic surfactants of the fatty alcohol ethersulfate type are distinguished by high foaming power, high cleaning power and low sensitivity to hardness and fats. Since, in addition, they are safe from the ecotoxicological point of view, they are often used in the production of manual dishwashing detergents and cosmetic products, such as for example hair shampoos, foam or shower baths. A certain disadvantage attending the use of fatty alcohol ethersulfates lies in their fatty odor which generally necessitates perfuming. However, changing market requirements have recently resulted in an increasing demand for lightly perfumed or perfume-free products and hence for odor-improved starting materials.
Accordingly, the problem addressed by the present invention was to provide a process for the production of substantially odorless ethersulfates.


DESCRIPTION OF THE INVENTION

This invention relates to a process for the production of substantially odorless fatty alcohol ethersulfate salts corresponding to formula (I): ion, ethoxylates and subsequent neutralization of the acidic sulfonation products, characterized in that technical fatty alcohol cuts are used in which the percentage content of volatile compounds, which have a boiling point under normal conditions below 235.degree. C., is at most 0.5% by weight, based on the cut as a whole.
It has surprisingly been found that, after ethoxylation and sulfation, fatty alcohol cuts which meet this requirement give fatty alcohol ethersulfates which are substantially odorless and which completely satisfy market requirements. As the outcome of extensive analytical investigations, the invention includes the observation that all the odor-causing secondary constituents of technical fatty alcohols, such as for example short-chain aldehydes, ketones, etc., have a boiling point under normal conditions below 235.degree. C.
In the context of the invention, normal conditions are understood to mean a temperature of 20.degree. C. and an external pressure of 1 atm.
Fatty alcohol ethersulfates are known surfactants which are obtained in known manner by reaction of fatty alcohols with ethylene oxide and subsequent sulfation of the resulting fatty alcohol ethoxylates. The process has proved to be of particular advantage for the production of substantially odorless fatty alcohol ether sulfates corresponding to formula (I), in which R.sup.1 is an alkyl radical containing 12 to 14 carbon atoms, n is a number of 2 to 5 and X represents sodium, magnesium, ammonium and/or alkanolammonium.
The ethoxylation reaction may be carried out in the presence of basic catalysts, such as sodium methylate for example, or layer compounds, such as hydrophobicized hydrotalcite for example, at temperatures of 150.degree. to 190.degree. C. Depending on the catalyst used, the resulting fatty alcohol ethoxylates may have a conventional homolog distribution or even a narrow homolog distribution.
The sulfation of the fatty alcohol ethoxylates may be carried out with gaseous sulfur trioxide or, preferably, chlorosulfonic acid, the molar ratio of fatty alcohol ethoxylate to sulfonating agent being from 1:0.9 to 1:1.3 and preferably from 1:0.95 to 1:1.05. To minimize the dioxane content of the sulfation products, it has proved to be of advantage to carry out the reaction at temperatures in the range from 15.degree. to 50.degree. C. and preferably at temperatures in the range from 25.degree. to 35.degree. C. and to keep the time elapsing between sulfation and neutralization as short as possible. The neutralization of the acidic products may be carried out with aqueous bases, for example sodium hydroxide, potassium hydroxide, magnesium hydroxide, ammonia or triethanolamine.
Technical fatty alcohol cuts having the following

REFERENCES:
patent: 4645627 (1987-02-01), Van Paassen et al.
patent: 4885379 (1989-12-01), Abend

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