Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfate esters
Reexamination Certificate
2002-06-19
2004-04-20
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfate esters
C568S864000
Reexamination Certificate
active
06723867
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to anionic surfactants and, more particularly, to substantially unsaturated fatty alcohol sulfates which, through the presence of branches in the hydrocarbon chain, are distinguished from linear homologs by significantly improved properties, to a process for their production and to their use for the production of surface-active compositions.
PRIOR ART
Sulfates of unsaturated fatty alcohols, which are essentially obtained by sulfation and subsequent neutralization of the corresponding tallow-based alkenols, are important raw materials for the production of both cosmetic preparations and laundry detergents, dishwashing detergents and cleaning products. The favorable properties of these substances are linked to the presence of the double bond in the molecule which also presents problems because the unsaturated fatty alcohol ether sulfates readily fall victim to autoxidation which is which is associated with discoloration and unwanted chemical changes (for example formation of peroxides and hydroperoxides).
Accordingly, it is clear that there is a need on the market for unsaturated fatty alcohol sulfates with improved oxidation stability or suitable substitutes which possess at least equivalent performance properties. However, more or less pure isostearyl alcohol sulfates have hitherto been the only alternatives to unsaturated fatty alcohol sulfates. To produce these more or less pure isostearyl alcohol sulfates, however, oleic acid first has to be dimerized, the fraction of monomeric branched fatty acids separated off, hydrogenated and subjected to fractional crystallization, the liquid fraction accumulating, which is rich in isostearic acid, has to be removed and esterified with methanol and the esters obtained subsequently hydrogenated to form the alcohols which, finally, are converted into the sulfates.
The process described above is technically complicated by the two hydrogenation steps and, in the isostearyl alcohol sulfates, provides substitutes which can only replace the unsaturated fatty alcohol sulfates to a limited extent. Accordingly, the problem addressed by the present invention was to provide unsaturated unsaturated fatty alcohol sulfates which would be distinguished by improved performance properties and preferably by higher oxidation stability.
DESCRIPTION OF THE INVENTION
The present invention relates to branched, substantially unsaturated fatty alcohol sulfates which are obtainable by
(a) dimerizing unsaturated C
16-22
fatty acids in known manner,
(b) removing the monomer fraction accumulating in the dimerization step,
(c) converting the branched, substantially unsaturated fatty acids present in this fraction into the corresponding fatty acid methyl esters,
(d) hydrogenating the branched, substantially unsaturated fatty acid methyl esters with the double bonds intact to form the corresponding branched, substantially unsaturated fatty alcohols and
(e) sulfating and neutralizing the branched, substantially unsaturated fatty alcohols in known manner.
It has surprisingly been found that the branched, substantially unsaturated fatty alcohol sulfates have distinctly improved autoxidation stability compared with linear homologs having the same chain length and the same iodine value. Further advantages include improved wetting behavior, quicker solubility in cold water and easier biodegradability.
The present invention also relates to a process for the production of branched, substantially unsaturated fatty alcohol sulfates in which
(a) unsaturated C
16-22
fatty acids are dimerized in known manner,
(b) the monomer fraction accumulating in the dimerization step is removed,
(c) the branched, substantially unsaturated fatty adds present in this fraction are converted into the corresponding fatty add methyl esters,
(d) the branched, substantially unsaturated fatty acid methyl esters are hydrogenated with the double bonds intact to form the corresponding branched, substantially unsaturated fatty alcohols which are then
(e) sulfated and neutralized in known manner.
Production of the Fatty Alcohols
The dimerization of fatty acids and the recovery of monomer fatty acids from the dimers is sufficiently well-known from the prior art, cf. for example the overviews by A. Behr et al. [Fat Sci. Technol. 93, 340 (1991)] and by H. Möhring et al. [ibid. 94, 41 (1992) and 94, 241 (1992)]. The sequence of steps (a) to (d) gives branched, substantially unsaturated fatty alcohols with iodine values of 45 to 85 on the basis of dimerized, preferably monounsaturated C
16-22
fatty acids, i.e. oleic acid, elaidic acid, petroselic acid, gadoleic acid and erucic acid and mixtures thereof. This is without doubt entirely adequate for a number of applications. However, in cases where fatty compounds with a relatively high content of unsaturated compounds are required, it is advisable to subject the monomer fraction accumulating in the dimerization step to fractional crystallization and then to subject the liquid phase obtained to esterification, optionally after distillation. The fatty acid obtained and its methyl esters represent an already fairly pure isooleic acid or isooleic acid methyl ester with Iodine values of 75 to 95. In any event, it is advisable to subject the methyl esters and/or the fatty alcohols to distillation and/or fractional crystallization (“winterizing”). The esterification of the fatty acids with methanol is carried out by known methods and is intended to produce methyl esters which are comparatively easy to hydrogenate. Instead of the methyl esters, other lower alkyl esters, for example ethyl, propyl or butyl esters, may of course also be produced and subsequently hydrogenated. The choice of the alcohol is basically not critical and is solely determined by economic criteria and availability. Instead of the methyl or lower alkyl esters, it is also possible in principle directly to esterify the fatty acids, although this does involve the use of special catalysts which do not form salts with the acids. In addition, the reactor material has to be corrosion-resistant. The hydrogenation of the unsaturated methyl esters to form the corresponding alcohols may also be carried out in known manner. Corresponding processes and catalysts, particularly those based on copper and zinc, are disclosed for example in the following documents: DE 43 357 81 C1, EP 0 602 108 B1, U.S. Pat. No. 3,193,586 and U.S. Pat. No. 3,729,520 (Henkel); reference is expressly made to the disclosures of these documents.
Sulfation and Neutralization
The conversion of the fatty alcohols previously obtained into the sulfates may also be carried out in known manner. The attack of the sulfating agent may be directed both at the hydroxyl group and at the double bond. However, since the sulfation process takes place about 10 times more quickly than sulfonation, i.e. the addition of sulfur trioxide onto the double bond, at low temperatures of the order of 30° C., sulfates are predominantly obtained (i.e. to an extent of more than 90% by weight). The reaction of the branched, substantially unsaturated fatty alcohols, for example with gaseous sulfur trioxide, may be carried out in the same way as described for fatty acid lower alkyl esters in J. Falbe (ed.), “Surfactants in Consumer Products”; Springer Verlag, Berlin-Heidelberg, 1987, page 61, reactors operating on the falling-film principle being preferred. In this known process, the sulfur trioxide is diluted with an inert gas, preferably air or nitrogen, and used in the form of a gas mixture which contains the sulfonating agent in a concentration of 1 to 8% by volume and, more particularly, 2 to 5% by volume. The molar ratio of fatty alcohol to sulfating agent is 1:0.95 to 1:1.8, preferably from 1:1.0 to 1:1.6 and more preferably from 1:1.3 to 1:1.5. The sulfation reaction is generally carried out at temperatures of 25 to 90° C. and preferably at temperatures of 35 to 80° C. Instead of sulfur trioxide, chlorosulfonic acid or amidosulfonic acid may also be used as the sulfonating agent. T
Huebner Norbert
Raths Hans-Christian
Westfechtel Alfred
Cognis Deutschland GmbH & Co. KG
Drach John E.
McKane Joseph K.
Saeed Kamal
LandOfFree
Branched, substantially unsaturated fatty alcohol sulfates does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Branched, substantially unsaturated fatty alcohol sulfates, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Branched, substantially unsaturated fatty alcohol sulfates will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3219511