Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
2000-02-16
2003-07-22
Rotman, Alan L. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S581000, C526S286000, C558S243000
Reexamination Certificate
active
06596899
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonates and derivatives thereof, as well as a process for making the same. Moreover, other functional end groups can be derived from the carboxylic acid end groups. The compounds can be utilized as initiators, chain transfer agents, or terminators for controlled free radical polymerizations. Free radical polymerizations utilizing s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compounds generally form telechelic polymers. If an initiator other than the s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compound is also utilized, a polymer having a single functional end group is formed in proportion to the amount of the initiator to the s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compound utilized.
BACKGROUND OF THE INVENTION
Although several members of the class of organic thiocarbonates have been known for many years and various routes have been employed for their synthesis, the s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compounds of the present invention have not been disclosed. Trithiocarbonate compounds have been claimed for various applications, such as pesticides for agriculture, and also as lubricating oil additives.
Traditional methods of producing block copolymers, such as by living polymerization or the linking of end functional polymers, suffer many disadvantages, such as the restricted type monomers which can be utilized, low conversion rates, strict requirements on reaction conditions, and monomer purity. Difficulties associated with end linking methods include conducting reactions between polymers, and problems of producing a desired pure end functional polymer. The s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compounds of the present invention can alleviate the above noted problems and difficulties when utilized in free radical polymerizations.
The prior art WO98/01478 reference discloses the use of thiocarbonates to conduct living free radical polymerizations. The reference is limited to alkyl and benzyl functional groups, and is unable to make any aryl or carboxylic acid substituted trithiocarbonates with general methods known to the art.
Synthesis
, p 894 (1986),
J. Chemical Research
(
Synopsis
), p478 (1995), and
Synthetic Communications
, Vol. 18, p 1531 (1988). We have also found the conversion for the dibenzyl derivatives disclosed in their example 26 to be very slow compared to the present invention when polymerizing acrylate, as can be seen in the Example section of this application.
SUMMARY OF THE INVENTION
The present invention relates to s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonates which have the general formula:
where R
1
and R
2
are set forth below, to derivatives thereof, and to a process for making the same.
The s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid) trithiocarbonate compounds can generally be formed from carbon disulfide, a haloform, and a ketone in a strong base, such as sodium hydroxide, followed by acidification. The s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid) trithiocarbonate compounds can be used as inifertors, i.e. as initiators and chain transfer agents, and/or chain terminators or as a chain-transfer agent during polymerization. The compounds can thus be utilized to control free radical polymerization thermally and chemically to give narrow molecular weight distributions. Polymerization of monomers can be in bulk, in emulsion, or in solution. Block copolymers can be made if two or more monomers are polymerized in succession. The difunctional acid end groups present can further react with other reactive polymers or monomers to form block or random copolymers. Free radical polymerizations utilizing the s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compounds generally form telechelic polymers. If an initiator other than the s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compound is also utilized, a polymer having a single functional end group is formed in proportion to the amount of said other initiator to the s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compound utilized.
DETAILED DESCRIPTION OF THE INVENTION
The s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate and derivatives prepared by the processes disclosed later herein generally can be described by the formula:
wherein R
1
and R
2
, independently, can be the same or different, and can be linear or branched alkyls having from 1 to about 6 carbon atoms, or a C
1
to about C
6
alkyl having one or more substituents, or one or more aryls or a substituted aryl group, having 1 to 6 substituents on the aryl ring, where the one or more substituents, independently, comprise an alkyl having from 1 to 6 carbon atoms; or an aryl; or a halogen such as fluorine or chlorine; or a cyano group; or an ether having a total of from 2 to about 20 carbon atoms such as methoxy, or hexanoxy; or a nitro; or combinations thereof. Examples of such compounds include s,s′-bis-2-methyl-2-propanoic acid-trithiocarbonate and s,s′-bis-(2-phenyl-2-propanoic acid)-trithiocarbonate. R
1
and R
2
can also form or be a part of a cyclic ring having from 5 to about 12 total carbon atoms. R
1
and R
2
are preferably, independently, methyl or phenyl groups.
The abbreviated reaction formula for the s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonates of the present invention can be generally written as follows:
The process utilized to form the s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compounds of the present invention is generally a multi-step process and includes combining the carbon disulfide and a base whereby an intermediate trithio structure is formed, see I, II, III, and IV. Ketone can serve as solvent for the carbon disulfide/base reaction and thus can be added in the first step of the reaction. In the second step of the reaction, the haloform, or haloform and ketone, or a &agr;-trihalomethyl-&agr;-alkanol are added to the trithio intermediate mixture and reacted in the presence of additional base, see V, VI, and VII. The formed reaction product, see IX, is subsequently acidified, thus completing the reaction and forming the above described s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compound, see X.
The reaction is carried out at a temperature sufficient to complete the interaction of the reactants so as to produce the s,s′-bis-(&agr;,&agr;′-disubstituted-&agr;″-acetic acid)-trithiocarbonate compound in a desired time. The reaction can be carried out at any temperature within a wide range from about the freezing point of the reaction mass to about the reflux temperature of the solvent. The reaction temperature is generally from about minus 15° C. to about 80° C., desirably from about 0° C. to about 50° C., and preferably from about 15° C. to about 35° C., with room temperature being preferred. The reaction can be performed at atmospheric pressure. The reaction time depends upon several factors, with the temperature being most influential. The reaction is generally complete within 20 hours and preferably within 10 hours.
A phase transfer catalyst is preferably utilized if a solvent is used in the reaction. Examples of solvents are set forth herein below. The ketone utilized in the reaction may double as a solvent, and therefore no catalyst usually is needed. The amount of phase transfer catalyst, when utilized in the present invention, is generally from about 0.1 mole percent to about 10
Dunlap Thoburn T.
Hudak, Shunk & Farine Co. LPA
Noveon IP Holdings Corp.
Oh Taylor V
Rotman Alan L.
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