Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1999-12-03
2001-08-28
Lee, Howard C. (Department: 1623)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S124000, C510S490000, C510S491000, C562S575000, C564S298000
Reexamination Certificate
active
06281176
ABSTRACT:
TECHNICAL FIELD
This invention relates to processes for preparing betaine/amine oxide mixtures from tertiary amines.
BACKGROUND
Many methods exist for making betaine/amine oxide mixtures. Very pure betaine/amine oxide mixtures are needed, particularly for pharmaceutical applications. Thus, there is a need for an efficient process for forming these betaine/amine oxide mixtures in high purity. It would be particularly advantageous if such a process did not require a separate purification step.
THE INVENTION
This invention provides a one-pot process for producing high purity betaine/amine oxide mixtures. A first reaction produces a betaine, and a second reaction produces an amine oxide, resulting in a betaine/amine oxide mixture. The high purity is achieved via separate additions of tertiary amine, which results in greater consumption of &ohgr;-halocarboxylate, and oxidation of virtually all free amine that has not been converted to betaine.
Accordingly, an embodiment of this invention provides a process for producing a betaine/amine oxide mixture. This process comprises reacting, in a liquid medium, an alkali metal &ohgr;-halocarboxylate with a first tertiary amine of the formula R
a
2
R
b
N, wherein each R
a
group is a hydrocarbyl group which independently has from 1 to about 4 carbon atoms, and wherein the R
b
group is a hydrocarbyl group which has from about 8 to about 24 carbon atoms, to produce a betaine product solution. To the betaine product solution is added a second tertiary amine of the formula R
a
2
R
b
N, wherein each R
a
group is a hydrocarbyl group which independently has from 1 to about 4 carbon atoms, and wherein the R
b
group is a hydrocarbyl group which has from about 8 to about 24 carbon atoms, to produce an amine/betaine mixture. In a carbon dioxide atmosphere, the amine/betaine mixture is mixed with hydrogen peroxide to yield a betaine/amine oxide mixture. The first and second tertiary amines can be separate portions of the same amine. Preferably, however, the first and second tertiary amines differ from each other.
This invention provides several advantages. The process of the invention can be conducted in one pot. No further steps beyond the one-pot process described herein are necessary to produce a very pure betaine/amine oxide mixture. The produced betaine/amine oxide mixture has a low free amine content (usually about 0.5 wt % or less), a very low nitrosodimethylamine content (usually about 5 parts per billion or less), and a low alkali metal &ohgr;-halocarboxylate content (usually about 0.05 wt % or less).
Further embodiments and features of the invention will be apparent from the ensuing description and appended claims.
A variety of solvents, or mixtures thereof, may be used as the liquid medium in this invention. Types of solvents include water, alcohols, esters, and ethers. Examples of suitable alcohols include methanol, ethanol, ethylene glycol, n-propanol, 2-propanol, 2-methyl-1-propanol, propylene glycol, n-butanol, 3-pentanol, cyclopentanol, 2-hexanol, 2-heptanol, and 1-octanol. Suitable esters include methyl acetate, ethyl acetate, methyl propionate, and ethyl propionate. Ethers suitable for use as the liquid medium include diethyl ether, ethyl n-propyl ether, diisopropyl ether, tetrahydrofuran, methyltetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, cyclohexylmethyl ether, glyme (the dimethyl ether of ethylene glycol), diglyme (the dimethyl ether of diethylene glycol), triglyme, and tetraglyme. Preferred solvents are water and ethanol. Highly preferred as the liquid medium is water.
The alkali metal &ohgr;-halocarboxylate is preferably the lithium, sodium, or potassium &ohgr;-halocarboxylate, and may be produced by the combination of alkali metal hydroxide with the appropriate &ohgr;-halocarboxylic acid. More preferably, the alkali metal &ohgr;-halocarboxylate is the sodium or potassium &ohgr;-halocarboxylate, and most preferably is the sodium &ohgr;-halocarboxylate. The &ohgr;-halocarboxylate may be, for example, haloacetate, 3-halopropionate, 4-halobutyrate, or 5-halovalerate. Most preferred as the &ohgr;-halocarboxylate is haloacetate. The halogen atom of the &ohgr;-halocarboxylate may be a chlorine, bromine, or iodine atom, is preferably a chlorine or bromine atom, and most preferably is a chlorine atom. Thus, the most preferred alkali metal &ohgr;-halocarboxylates are sodium chloroacetate and sodium bromoacetate; sodium chloroacetate is most highly preferred.
Both the first tertiary amine and the second tertiary amine used in the process of this invention have the formula R
a
2
R
b
N. R
a
is a hydrocarbyl group which has from 1 to about 4 carbon atoms. Suitable hydrocarbyl groups include methyl, ethyl, isopropyl, cyclopropyl, sec-butyl, tert-butyl, n-butyl, and cyclobutyl. While R
a
is preferably a straight chain, it may also be a branched or cyclic hydrocarbyl group. The two R
a
groups may be the same or different, but are preferably the same. It is highly preferred that both R
a
groups are methyl groups. R
b
is a hydrocarbyl group which has from about 8 to about 24 carbon atoms. Examples of suitable hydrocarbyl groups include, but are not limited to, octyl, 4-methylcyclooctyl, nonyl, 3-nonenyl, decyl, 3-methyl-5-undecenyl, dodecyl, tetradecyl, 8-cyclohexyloctyl, 6-ethyldodecyl, hexadecyl, octadecyl, eicosyl, and n-tetracosyl. R
b
may be a straight chain, a branched, or a cyclic group, but is preferably a straight chain hydrocarbyl group. Saturated hydrocarbyl groups are preferred, although R
b
may be an unsaturated hydrocarbyl group. Preferably, R
b
has from about 8 to about 18 carbon atoms. Highly preferred as the hydrocarbyl group of R
b
are a n-tetradecyl group and a n-hexadecyl group. The most highly preferred tertiary amines are thus N,N-dimethyltetradecylamine and N,N-dimethylhexadecylamine. Particularly preferred is the use of N,N-dimethylhexadecylamine as the first tertiary amine and N,N-dimethyltetradecylamine as the second tertiary amine.
As noted above, the betaine and the amine oxide may be synthesized from different amines or from two separate additions of the same amine. While less preferred, the first amine and/or the second amine may comprise a mixture of two or more amines. An advantage of adding the amine(s) in two separate steps is that the proportion of amine that forms betaine and the proportion of amine that forms amine oxide can be controlled. Selection of which amine forms the betaine and which forms the amine oxide is another advantage of separate addition of the amines when the first amine and the second amine are different.
When reacting an alkali metal &ohgr;-halocarboxylate with a first tertiary amine, a slight excess of the alkali metal &ohgr;-halocarboxylate relative to the tertiary amine is preferred. The liquid medium may be added to the reaction vessel prior to both the amine and the alkali metal &ohgr;-halocarboxylate, or concurrently with them. One or both reactants may be co-fed to the reaction vessel with the liquid medium. A preferred addition method is mixing the amine with liquid medium, followed by the addition of alkali metal &ohgr;-halocarboxylate dissolved in another portion of liquid medium. More preferably, the alkali metal &ohgr;-halocarboxylate in a portion of liquid medium is added to a solution of amine in liquid medium which has already been heated to the desired reaction temperature. For this reaction, the temperature may be in the range of from about 60° C. to about 100° C., and preferably is in the range of from about 70° C. to about 90° C. The pH of the solution should be in the range of from about 7.5 to about 12, and is preferably in the range of from about 8 to about 10. Often, the addition of base during the reaction is necessary to maintain the pH in the desired range. Such base may be added periodically or continuously. Preferred bases are the alkali metal hydroxides, and sodium hydroxide is the most preferred base. Reaction times typically range from about 3 hours to about 48 hours. More preferable reaction times are in the range of from about 10 hours to about 30
Cochran Rebecca S.
Hu Patrick C.
McCaig Michael S.
Perkins, Jr. Edmund F.
Sauer Joe D.
Albemarle Corporation
Lee Howard C.
Maier Leigh C.
Spielman, Jr. E. E.
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