Process for producing fluoroaromatic carboxylates

Details Process for producing fluoroaromatic carboxylates Process for producing fluoroaromatic carboxylates

2000-06-13

2002-04-02

Geist, Gary (Department: 1623)

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

Organic compounds

Carboxylic acids and salts thereof

C562S473000, C560S070000

Reexamination Certificate

active

06365773

ABSTRACT:

TECHNICAL FIELD
This invention concerns a process in which fluoroaryl Grignard reagents are converted to fluoroaryl carboxylates via reaction with carbon dioxide.
BACKGROUND
The carboxylation of Grignard reagents using carbon dioxide is well known in the art, and several carboxylations of fluoroaryl Grignard reagents have been reported. See in this connection U.S. Pat. No. 3,412,162; G.B. Pat. No. 1,027,355; and Vorozhtsov, Jr., et al.,
Doklady Akademii Nauk SSSR
, 1964, 159, 125. These are carried out by bubbling carbon dioxide into a solution of the Grignard reagent; yields tend to be low. A higher yield was achieved by Harper et al.,
J. Org. Chem
., 1964, 29, 2385, using solid carbon dioxide, the use of which is not feasible on a commercial scale.
THE INVENTION
This invention makes possible the formation of a fluoroaryl carboxylate from a fluoroaryl Grignard reagent via contact with carbon dioxide in significantly higher yields than was previously possible. Furthermore, this process can be carried out in a commercially feasible, highly efficient manner on a continuous basis.
An embodiment of this invention is a process for producing a halomagnesium fluoroaryl carboxylate. This process comprises adding at least one fluoroaryl Grignard reagent to an anhydrous liquid ethereal medium pretreated with carbon dioxide. The aryl group of the fluoroaryl Grignard reagent is a fluorine-containing aryl group, which has bonded directly to an aromatic ring at least two fluorine atoms, or at least two perfluorohydrocarbyl groups, or at least one fluorine atom and at least one perfluorohydrocarbyl group.
Another embodiment of this invention is a continuous process for producing a halomagnesium fluoroaryl carboxylate. This process comprises continuously and concurrently cofeeding carbon dioxide and at least one fluoroaryl Grignard reagent to a reactor, while periodically or continuously removing product solution from the reactor. The aryl group of the fluoroaryl Grignard reagent is a fluorine-containing aryl group, which has bonded directly to an aromatic ring at least two fluorine atoms, or at least two perfluorohydrocarbyl groups, or at least one fluorine atom and at least one perfluorohydrocarbyl group.
Further embodiments of the invention will be apparent from the ensuing description and appended claims.
The fluoroaryl group of the fluoroaryl Grignard reagent has bonded directly to the aromatic ring at least two fluorine atoms, or at least two perfluorohydrocarbyl groups, or at least one fluorine atom and at least one perfluorohydrocarbyl group. It is preferred that at least two fluorine atoms or at least two perfluorohydrocarbyl groups are bonded directly to the aromatic ring. Each position on the aromatic ring(s) of the fluoroaryl group that is not a fluorine atom or a perfluorohydrocarbyl group is substituted by a hydrogen atom, a hydrocarbyl group, an alkoxy group, or a silyl group.
The halogen atom of the halomagnesium moiety of the fluoroaryl Grignard reagent may be a chlorine atom, bromine atom, or iodine atom. Preferred halogen atoms are chlorine and bromine. Thus, the halomagnesium moiety is preferably a bromomagnesium moiety or a chloromagnesium moiety.
Throughout this document, the term “fluoroaryl group” shall be understood, when not specified, to mean, as described above, a fluorine-containing aryl group, which has bonded directly to an aromatic ring at least two fluorine atoms, or at least two perfluorohydrocarbyl groups, or at least one fluorine atom and at least one perfluorohydrocarbyl group. It is preferred that at least two fluorine atoms or at least two perfluorohydrocarbyl groups are bonded directly to an aromatic ring. Each position on the aromatic ring(s) of the fluoroaryl group that is not a fluorine atom or a perfluorohydrocarbyl group is substituted by a hydrogen atom, a hydrocarbyl group, an alkoxy group, or a silyl group. The aromatic ring of the fluoroaryl group may be, but is not limited to, phenyl, 1-naphthyl, 2-naphthyl, anthryl, biphenylyl, phenanthryl, or indenyl. Phenyl is the preferred aromatic moiety. The perfluorohydrocarbyl substituent groups, when present, include alkyl and aryl perfluorocarbons; suitable perfluorohydrocarbyl groups are, for example, trifluoromethyl, pentafluoroethyl, pentafluorophenyl, and heptafluoronaphthyl. The hydrocarbyl groups of the aryl groups are preferably C
1
to C
18
alkyl groups or C
6
to C
20
aryl or aralkyl groups. Examples of suitable hydrocarbyl groups are methyl, ethyl, isopropyl, tert-butyl, cyclopentyl, methylcyclohexyl, decyl, phenyl, tolyl, xylyl, benzyl, naphthyl, and tetrahydronaphthyl. The alkoxy groups preferably have C
1
to C
6
alkyl moieties. Some examples of alkoxy groups are methoxy, ethoxy, isopropoxy, methylcyclopentoxy, and cyclohexoxy. The silyl groups preferably have C
1
to C
18
alkyl groups or C
6
to C
20
aryl or aralkyl groups. Suitable silyl groups include trimethylsilyl, triisopropylsilyl, tert-butyl(dimethyl)silyl, tridecylsilyl, and triphenylsilyl. Examples of fluoroaryl groups that can be part of the Grignard reagent in this invention include 3,5-bis(trifluoromethyl)phenyl, 2,4,6-tris(trifluoromethyl)-phenyl, 4-[tri(isopropyl)silyl]-tetrafluorophenyl, 4-[dimethyl(tert-butyl)silyl]-tetrafluorophenyl, 4′-(methoxy)-octafluorobiphenylyl, 2,3-bis(pentafluoroethyl)-naphthyl, 2-(isopropoxy)-hexafluoronaphthyl, 9,10-bis(heptafluoropropyl)-heptafluoroanthryl, 9,10-bis(p-tolyl)-heptafluorophenanthryl, and 1-(trifluoromethyl)-tetrafluoroindenyl. It is preferred that at most two substituents on the ring of the fluoroaryl group are hydrocarbyl, perfluorohydrocarbyl, or alkoxy.
It is highly preferred to have fluoroaryl groups in which all of the substituents are fluorine atoms. Examples of such groups are pentafluorophenyl, 4-nonafluorobiphenylyl, 2-nonafluorobiphenylyl, 1-heptafluoronaphthyl, 2-heptafluoronaphthyl, 7-nonafluoroanthryl, 9-nonafluorophenanthryl, and analogous groups. The most highly preferred perfluoroaryl group is pentafluorophenyl.
Preferred fluoroaryl Grignard reagents include pentafluorophenylmagnesium bromide, heptafluoronaphthylmagnesium chloride, 2-nonafluorobiphenylylmagnesium chloride, 3,5-bis(trifluoromethyl)phenyl bromide, and 2,3-bis(pentafluoroethyl)-naphthylmagnesium chloride. The most highly preferred fluoroaryl Grignard reagents are pentafluorophenylmagnesium bromide and pentafluorophenylmagnesium chloride.
A feature of this invention is pretreatment of a liquid ethereal medium with carbon dioxide prior to the introduction of the fluoroaryl Grignard reagent to the liquid ethereal medium. The liquid ethereal medium that is pretreated with carbon dioxide is comprised of one or more liquid ethers. Any of a variety of monoethers or polyethers may be used, and they may be aliphatic, aromatic, alkylaromatic, and/or cyclic ethers. Examples of ethers that may be used include diethyl ether, ethyl n-propyl ether, di-n-propyl ether, diisopropyl ether, di-n-butyl ether, n-butyl methyl ether, cyclohexyl methyl ether, methoxybenzene, n-butyl phenyl ether, dibenzyl ether, o-xylylene oxide (phthalan), 1,4-benzodioxan, dihydrobenzopyran (chroman), isochroman, trimethylene oxide, 3,3-dimethyltrimethylene oxide, tetrahydrofuran, methyl tetrahydrofuran, tetrahydropyran, 1,4-dioxane, 1,3-dioxane, 1,3-dioxolane, 1,3-dioxepane, glyme (the dimethyl ether of ethylene glycol), diglyme (the dimethyl ether of diethylene glycol), triglyme, and tetraglyme. Unsubstituted cyclic ethers are preferred. Thus, preferred ethers include tetrahydrofuran, tetrahydropyran, 1,3-dioxane, and 1,3-dioxolane. Tetrahydrofuran is an especially preferred liquid ethereal medium in the practice of this invention.
The fluoroaryl Grignard reagent is in a liquid medium. Normally and preferably, this liquid medium is one or more ethers. Ethers in which the fluoroaryl Grignard reagent can be include, for example, those described above for the liquid medium that is pretreated with carbon dioxide. An especially preferred ether for the fluoroaryl Grignard reagent in this invention is tetrahyd

Affiliated with

Also associated with

Rating

Process for producing fluoroaromatic carboxylates does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for producing fluoroaromatic carboxylates, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing fluoroaromatic carboxylates will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2902570