Organic compounds -- part of the class 532-570 series – Organic compounds – Compounds having the group -c
Reexamination Certificate
2000-01-24
2001-07-31
Gitomer, Ralph (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Compounds having the group -c
C435S197000, C435S198000
Reexamination Certificate
active
06268523
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a process for the preparation of a tertiary perester by contacting an acyl compound with a tertiary hydroperoxide.
Tertiary peresters are commercially important initiators for the polymerization of monomers in particular, to acrylics, polyethylene, polyvinylchloride, and styrenics. Tertiary peresters are also used for the modification of these and other polymers. For the various methods of synthesis of peresters we refer to D. Swern, Ed.,
Organic Peroxides
, Volumes I and II, 1970 and 1971, respectively, Wiley-Interscience, New York. On a commercial scale, tertiary peresters are prepared from tertiary hydroperoxides and acid chlorides in particular. This process has the disadvantage that acid chlorides are expensive starting materials. A further drawback is that the use of acid chlorides leads to the formation of hydrogen chloride, which is a corrosive. Also, the use of acid chlorides presents a problem in the form of chloride waste. Accordingly, there is a need for improved methods of preparing tertiary peresters.
Incidentally, Baba et al.,
Agric. Biol. Chem
. 52 (1988) 2685-2687 describe the occurrence of enzymatic synthesis of hydroperoxides in the course of an enzymatic resolution of racemic secondary hydroperoxides in organic solvent by reaction with isopropenyl acetate in the presence of a lipoprotein lipase from Pseudomonas fluorescens (LPL Amano P). In this way, one enantiomer is acylated while the other enantiomer remains in the reaction mixture as the hydroperoxide. Acylated primary and secondary hydroperoxides are said to disintegrate spontaneously to carboxylic acid and aldehyde or ketone, respectively. More importantly, it is mentioned that no acylation reaction occurred starting from 1-methyl-1-phenylpropyl hydroperoxide.
Höft et al. in
Tetrahedron: Asymmetry
5 (1995) 603-608 also describe that 1-methyl-1-phenylpropyl hydroperoxide and 1-cyclohexyl-1-phenylethyl hydro-peroxide are not converted into the corresponding tertiary peresters using the same lipase.
Further, several publications describe the enzyme-catalyzed synthesis of peracids. In PCT Patent Publication No. WO 91/04333, for example, a process for preparing peroxycarboxylic acids from a carboxylic acid and hydrogen peroxide using an enzyme catalyst is described. The preparation of tertiary peresters is not disclosed in these publications.
SUMMARY OF THE INVENTION
Surprisingly, we have found a new, commercially attractive process to prepare tertiary peresters which does not suffer from the above-mentioned disadvantages. The process according to the present invention is characterized in that an acyl compound of formula R
1
[C(O)OR
2
]
n
, wherein R
1
is a linear or branched, saturated or unsaturated C
1
-C
22
group, optionally containing one or more hetero atoms, R
2
represents hydrogen or has the same meaning as described for R
1
, and n is 1-5, or a polyalcohol ester of R
1
C(O)OH, wherein R
1
has the same meaning as described above, is contacted with a tertiary hydroperoxide of formula [HOOCR
3
R
3
]
m
R
4
, wherein R
3
represents either a methyl or an ethyl group, R
4
has the same meaning as described for R
1
, and m is 1-5, in the presence of an enzyme catalyst.
DESCRIPTION OF PREFERRED EMBODIMENTS
The term “tertiary peresters” in the present application refers to peresters in which the peroxy &agr;-carbon atom is a tertiary carbon atom.
Typically, in accordance with the formulae previously described, R
1
is a C
1
-C
22
alkyl, C
3
-C
22
cycloalkyl, C
6
-C
22
aryl, C
7
-C
22
aralkyl, or C
7
-C
22
alkaryl group. Preferably, R
1
is a linear or branched C
1
-C
11
alkyl group or a phenyl group, R
2
is hydrogen or a methyl or ethyl group, n is 1 or 2, R
3
is a methyl group, m is 1 or 2, and/or R
4
is a linear or branched C
1
-C
5
alkyl group or a phenyl group. More preferably, R
4
is a methyl, ethyl, propyl, neopentyl, or phenyl group, most preferably a methyl or ethyl group. Most preferably, n and m are 1. It is preferred that when R
3
is an ethyl group, R
4
is a linear or branched C
1
-C
5
alkyl group. Polyalcohol esters of R
1
C(O)OH can also be used in the invention process and are attractive acyl compounds. A particularly preferred class of polyalcohol esters are glycerol esters, so-called glycerides. Either one, two, or all three hydroxy groups of glycerol may be esterified with R
1
C(O)OH. Triglycerides are most preferred since they are readily available. Glycerol esters can be isolated from natural sources, e.g. animals and plants fats and oils, and they typically contain fatty acyl groups having 12 to 22 carbon atoms, namely, R
1
is a C
12
-C
22
group. These fatty acyl groups may be saturated or unsaturated, and may contain functional groups such as hydroxy groups, as for example in ricinoleic acid.
Typical examples of tertiary hydroperoxides which can be used in the invention process include: tert-butyl hydroperoxide, 1,1-dimethyl-1-propyl- (or tert-amyl) hydroperoxide, 1,1-dimethyl-1-butyl- (or tert-hexyl) hydroperoxide, 1-methyl-1-ethyl-1-propyl-hydroperoxide, 1,1,2-trimethylpropyl-1-hydro-peroxide, cumyl hydroperoxide, 1,1-dimethyl-3-hydroxy-1-butyl- (or hexylene-glycol) hydroperoxide, 1,1,3,3-tetramethylbutyl-hydroperoxide, 2,5-dimethyl-2,5-dihydroperoxyhexane, 2,5-dimethyl-2,5-dihydroperoxyhex-3-yn, cyclo-hexane-1,4-di-(2-propyl-2-hydroperoxide), cyclohexane-1,3-di-(2-propyl-2-hydroperoxide), benzene-1,4-di-(2-propyl-2-hydroperoxide), and benzene-1,3-di-(2-propyl-2-hydroperoxide).
Typical examples of acyl compounds which can be used in the process according to the invention include: acetic acid, phenylacetic acid, phenoxyacetic acid, propanoic acid, isobutyric acid, benzoic acid, 2-methyl-benzoic acid, 2-methylbutanoic acid, 2-butenoic acid, 3-phenylpropenic acid, 2,2-dimethylpropanoic acid, 2,2-dimethylbutanoic acid, 2,2-dimethyl-pentanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, 2-ethylbutanoic acid, neohexanoic acid, neoheptanoic acid, neodecanoic acid, octanoic acid, nonanoic acid, lauric acid, 2,4,4-trimethylpentanedioic acid, hexanedioic acid, 2,2,4-trimethylhexanedioic acid, 2,4,4-trimethylhexanedioic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, cyclo-hexanecarboxylic acid, 1,4-cyclohexanedicarboxylic acid, cyclohexane-1,4-diacetic acid, maleic acid, citric acid, 3-hydroxybutanoic acid, 4-hydroxybutanoic acid, 2-hydroxy-pentanoic acid, 3-hydroxypentanoic acid, 4-hydroxypentanoic acid, 5-hydroxypentanoic acid, hydroxyacetic acid, 2-hydroxyisobutyric acid, 2-hydroxypropanoic acid, 2-hydroxyhexanoic acid, hydroxypivalic acid, hydroxy-succinic acid, methylsuccinic acid, citraconic acid, fumaric acid, oxalic acid, terephthalic acid, propenoic acid, phthalic acid, 3-ketopentanoic acid, 4-ketopentanoic acid, and 3-ketoglutaric acid, and their corresponding methyl esters, ethyl esters, n-propyl esters, isopropyl esters, n-butyl esters, sec-butyl esters, isobutyl esters, ethylene glycol esters, and propylene glycol esters.
Specific examples of tertiary peresters which can be prepared by the process according to the present invention include:
cumyl peroxyneodecanoate
2,4,4-trimethylpentyl-2 peroxyneodecanoate
tert-amyl peroxyneodecanoate
tert-butyl peroxyneodecanoate
tert-amyl peroxypivalate
tert-butyl peroxypivalate
2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane
tert-amyl peroxy-2-ethylhexanoate
tert-butyl peroxy-2-ethylhexanoate
tert-butyl peroxydiethylacetate
tert-butyl peroxyisobutanoate
tert-butyl peroxy-3,5,5-trimethylhexanoate
tert-butyl peroxyacetate
tert-butyl peroxybenzoate
1,4-bis(tert-butylperoxycarbo)cyclohexane
Two compounds having two tertiary perester functionalities are 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane and 1,4-bis(tert-butyl-peroxy-carbo)-cyclohexane. The first compound is prepared by reacting a bistertiary hydroperoxide, i.e., m=2, and an acyl compound, the second is synthesized by contacting a cyclohexane-derived bisacyl compound, i.e., n=2, with a tertiary hydroperoxide.
R
1
and R
4
may optionally cont
Cuperus Folkert P.
Derksen Johannes T. P.
Kramer Gerardus F. H.
Meijer John
Tammer Marinus C.
Akzo Nobel nv
Fennelly Richard P.
Gitomer Ralph
Khare Devesh
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