Branched surfactant manufacture

Details Branched surfactant manufacture Branched surfactant manufacture

2001-09-06

2002-08-13

Solola, T. A. (Department: 1626)

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

Organic compounds

Sulfate esters

Reexamination Certificate

active

06433207

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to processes for manufacturing detersive surfactants, especially those containing branched-chain hydrophobic units.
BACKGROUND OF THE INVENTION
Conventional detersive surfactants comprise molecules having a water-solubilizing substituent (hydrophilic group) and an oleophilic substituent (hydrophobic group). Such surfactants typically comprise hydrophilic groups such as carboxylate, sulfate, sulfonate, amine oxide, polyoxyethylene, and the like, attached to an alkyl, alkenyl or alkaryl hydrophobe usually containing from about 10 to about 20 carbon atoms. Accordingly, the manufacturer of such surfactants must have access to a source of hydrophobe groups to which the desired hydrophile can be attached by chemical means. The earliest source of hydrophobe groups comprised the natural fats and oils, which were converted into soaps (i.e., carboxylate hydrophile) by saponification with base. Coconut oil and palm oil are still used to manufacture soap, as well as to manufacture the alkyl sulfate (“AS”) class of surfactants. Other hydrophobes are available from petrochemicals, including alkylated benzene which is used to manufacture alkyl benzene sulfonate surfactants (“LAS”).
The literature asserts that certain branched hydrophobes can be used to advantage in the manufacture of alkyl sulfate detersive surfactants; see, for example, U.S. Pat. No. 3,480,556 to deWitt, et al., Nov. 25, 1969. However, it has been determined that the beta-branched surfactants described in the '556 patent are inferior with respect to certain solubility parameters, as evidenced by their Krafft temperatures. It has further been determined that surfactants having branching towards the center of carbon chain of the hydrophobe have much lower Krafft temperatures. See: “The Aqueous Phase Behavior of Surfactants”, R. G. Laughlin, Academic Press, N.Y. (1994) p. 347. Accordingly, it has now been determined that such surfactants are preferred for use especially under cool or cold water washing conditions (e.g., 20° C.-5° C.).
One problem associated with the manufacture of detersive surfactants having hydrophobe groups with mid- or near-mid chain branching is the lack of a ready source of such hydrophobes. By the present invention, a process is described for manufacturing such branched hydrophobes and converting them into mid- or near-mid chain branched surfactants.
SUMMARY OF THE INVENTION
The present invention encompasses a process for preparing mid- to near mid-chain branched olefins (primarily, methyl branched at or near the mid-chain region). Such materials are then used as the basic feedstock which provides the hydrophobic portion of branched-chain detersive surfactants.
The process herein is illustrated by the following reaction sequence.
1) Alpha-Olefin Dimerization
wherein R and R′ may be the same or different linear alkyl, and wherein R is C
3
-C
7
, preferably C
5
to C
7
linear alkyl, and R′ is C
3
-C
7
, preferably C
5
-C
7
linear alkyl. For use in preparing surfactants in cleaning products such as laundry detergents, dishwashing liquids, and the like, R and R′ are preferably the same or within one or two carbon atoms of each other in chain length. Some linear olefins may also result from the dimerization and these can optionally be removed using molecular sieves. Step 1 of the process herein is designed to provide branched olefins which preferably contain from about 12 to about 18 (avg.) total carbon atoms.
2) Alcohol Production
In Step 2 (Route A), the olefin mixture for Step 1 can be pre-randomized to enhance the ultimate formation of alcohols (i) and (ii) in subsequent Step 3. Alternatively (Step 2, Route B), this pre-randomization step can be deleted and the Oxo catalyst, itself, can randomize the final product among the three possible terminal positions.
The Oxo process to make alcohols is described in detail in Kirk-Othmer
Encyclopedia of Chemical Technology
, 4th Edition, Volume 1, pp. 903-8 (1991), Jacqueline 1. Kroschwitz, Executive Editor, Wiley-Interscience, N.Y. The catalyst for this step is, for example, cobalt-carbon monoxide-organophosphine.
The alcohol mixture of Step (2) of the present process comprises branched-chain primary alcohol compounds of the following formulae for use in Step (3), below.
It is to be understood that when CH
2
OH is substituted on R or R′ it is primarily on their respective terminal carbons or to a lesser extent on their penultimate carbons. Desirably, minimal amounts of compounds of the formula (iii) are present in Step (3).
3) Surfactant Production
Advantageously, the present process results in no geminal branching; i.e., no “quaternary” carbon substitution. Steric hindrance will block inverse addition to vinylidene carbon with cobalt-carbon monoxide-organophosphine which otherwise would form a non-biodegradable quaternary carbon. Moreover, little (less than about 3%) vicinal branching occurs. Of course, some of the overall feedstock may remain unbranched. Typically, and preferably from the standpoint of cleaning performance and biodegradability, the present process provides hydrophobes with one near-central methyl in the case of isomers i) and ii).
All percentages, ratios and proportions herein are by weight, unless otherwise specified. All documents cited herein are, in relevant part, incorporated herein by reference.
DETAILED DESCRIPTION OF THE INVENTION
1) Olefin Dimerization:
The present invention encompasses, in a process for preparing surfactant precursor hydrophobes from dimerization of two same or near same chain length alpha-olefins to form a detergent range vinylidene olefin. These alpha olefins C
5
to C
10
, preferably C
7
to C
9
are dimerized to give C
10
to C
20
, preferably C
14
to C
18
vinylidene olefins which upon Oxo reaction give C
11
to C
21
, preferably C
15
to C
19
alcohols. There are a number of processes for accomplishing said dimerization; see U.S. application Ser. No. 9,200,398, U.S. Pat. No. 4,658,078, U.S. Pat. No. 4,973,788; O. S. Vostrikova, A. G. Ibragimov, G. A. Tolstikov, L. M. Zelenova and U. M. Dzhemilev, Izv. Akad. Nauk SSSR, Ser. Khim. (1980), (10), 2330-2 [Chem. Abstr. 94:65032]; Jpn. Kokai Tokkyo Koho, 06228016 A2 [Chem. Abstr. 122:186930].
2) Alcohol Production
Route A
part a) The carbon-carbon double bond of the vinylidene olefin is pre-isomerized using a method such as Shell uses to isomerize alpha-olefins in their SHOP process; see
Kirk
-
Othmer Encyclopedia of Chemical Technology
, 4th Edition, Volume 17, pp. 848-50 (1996), Jacqueline I. Kroschwitz, Executive Editor, Wiley-Interscience, N. Y. and
Chemical Economics Handbook
, pp. 681.5030K-L, Stanford Research Institute, Menlo Park, Calif. 94025, October 1993.
part b) Oxo chemistry is used to convert the pre-isomerized vinylidene olefin (now largely internal olefin) to a primary alcohol mixture. For this an Oxo catalyst which isomerizes the double bond to alpha positions prior to carbonylation is desired as is the case using cobalt-carbonyl-phosphine catalysts in the one step process, see
Kirk
-
Othmer Encyclopedia of Chemical Technology
, 4th Edition, Volume 1, pp. 903-8 (1991). Route A, (that is including pre-isomerization) is undertaken to assure relatively high yields of alcohols i and ii versus alcohol iii. Note alcohol sulfates of i and ii are desired surfactants whereas that of iii may be deficient.
Route B
This step utilizes the same Oxo catalyst on the vinylidene olefin directly without its pre-isomerization. This relies upon the catalyst to completely isomerize the carbon—carbon double bond of the vinylidene olefin prior to carbonylation. The object is to obtain as much i and ii relative to iii as is obtained in Route A.
Other fatty alcohol-derived surfactants can also be made, e.g., alkyl ethoxyl sulfates (AES), alkyl polyglucosides (APG), etc. Note that surfactants other than alcohol sulfates or AES may be made by oxidizing said alcohol or its aldehyde intermediate into a carboxylate (i.e., a branched-chain soap). This soap can be an exce

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