Method for producing halogenketones

Abstract

The present invention describes a novel method for producing haloketones.

Claims

1. Method for producing one or more haloketones of formula (I)
R.sup.1COCH.sub.3(I), where R.sup.1 is haloalkyl, comprising cleaving one or more ketoesters of formula (II)
R.sup.1COCH.sub.2COOR.sup.2(II), where R.sup.2 is alkyl or benzyl and R.sup.1 is as defined above, in the presence of phosphoric acid and without the addition of a carboxylic acid.

2. Method according to claim 1, wherein R.sup.1 is selected from CF.sub.3, CF.sub.2H, or CF.sub.2Cl; and R.sup.2 is selected from methyl, ethyl, n-propyl, or benzyl.

3. Method according to claim 1, wherein R.sup.1 is CF.sub.2H; and R.sup.2 is selected from methyl or ethyl.

4. Method according to claim 1, wherein said method is carried out at a temperature of from 70 C. to 130 C.

5. Method according to claim 1, wherein said method is carried out as a continuous operation.

6. A process for manufacturing a fungicidally active agent comprising the method according to claim 1.

Description

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

(1) Preference is given to a process according to the invention in which the radicals of the compounds of formulas (I) and (II) are defined as follows:

(2) R.sup.1 is selected from CF.sub.3, CF.sub.2H, CF.sub.2Cl;

(3) R.sup.2 is selected from methyl, ethyl, n-propyl, benzyl.

(4) Particular preference is given to a process according to the invention in which the radicals of the compounds of formulas (I) and (II) are defined as follows:

(5) R.sup.1 is CF.sub.2H;

(6) R.sup.2 is selected from methyl, ethyl.

GENERAL DEFINITIONS

(7) Haloalkyl: straight-chain or branched alkyl groups having 1 to 6 and preferably 1 to 3 carbon atoms, wherein some or all of the hydrogen atoms in these groups may be replaced by halogen atoms as mentioned above, for example (but not limited to) C.sub.1-C.sub.3-haloalkyl such as chloromethyl, bromomethyl, dichloromethyl, trichloromethyl, fluoromethyl, difluoromethyl, trifluoromethyl, chlorofluoromethyl, dichlorofluoromethyl, chlorodifluoromethyl, 1-chloroethyl, 1-bromoethyl, 1-fluoroethyl, 2-fluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl, 2-chloro-2-fluoroethyl, 2-chloro-2-difluoroethyl, 2,2-dichloro-2-fluoroethyl, 2,2,2-trichloroethyl, pentafluoroethyl and 1,1,1-trifluoroprop-2-yl.

(8) Alkyl groups are for the purposes of the present invention linear, branched or cyclic saturated hydrocarbon groups. The definition C.sub.1-C.sub.12-alkyl encompasses the widest range defined herein for an alkyl group. Specifically, this definition encompasses methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and t-butyl, n-pentyl, n-hexyl, 1,3-dimethylbutyl, 3,3-dimethylbutyl, n-heptyl, n-nonyl, n-decyl, n-undecyl or n-dodecyl for example.

METHOD DESCRIPTION

(9) ##STR00001##

(10) The ketoester compounds of formula (II) used as starting compounds are known and commercially available. The temperature during the reaction according to the invention is in the range of from 20 C. to 200 C., preferably in the range of from 70 C. to 130 C.

(11) The method according to the invention can optionally be run as a continuous operation.

(12) The quantity of H.sub.3PO.sub.4 is between 5 to 500 g for 1 mol of the compound of formula (I), preferably 20-350 g. Once the product has been isolated, the H3PO4 is reused without purification. At least 5 such cycles are possible without a drop in yield. It is preferable to use aqueous H.sub.3PO.sub.4 solution. The concentration of the H.sub.3PO.sub.4 is 20-85%, preferably 85%. It is preferable to use technical-grade material having a content of 70-85%. It is also possible to use polyphosphoric acid. The reaction is optionally carried out in an inert solvent such as chlorobenzene, toluene. Corrosion of glass and metallic materials of construction was not observed for this method.

EXAMPLE 1

Difluoroacetone HCF2COCH3

(13) 150 ml of H.sub.3PO.sub.4 (85% w/w) were initially charged to a 250 ml multi-necked flask equipped with a distillation bridge and heated to 100 C. to 105 C. 132 g of 91% w/w purity ethyl difluoroacetoacetate (0.720 mol) were added over 3 hours via a syringe pump. The distillate of boiling point 40-60 C. was continuously removed within 5 hours. The reaction is complete after 5 hours. A total of 75 g of clear colourless liquid were collected.

(14) The composition of the fraction (determined by .sup.19F NMR) is:
70% w/w HCF.sub.2COCH.sub.3
11% w/w HCF.sub.2C(OH).sub.2CH.sub.3 hydrate
14% w/w HCF.sub.2C(OEt)(OH)CH.sub.3 monoketal

(15) The mixture can be further used without purification. If desired, a second distillation over H.sub.3PO.sub.4 can be carried out for further purification. Hydrate and monoketal are simultaneously cleaved and converted to difluoroacetone.

(16) Using 5 g of H.sub.3PO.sub.4 affords after distillation 67 g of difluoroacetone (HCF.sub.2COCH.sub.3) with a purity of 95% to 96%. The yield is 94% to 95%.