IL35690A - 3-halo-2,6-dinitro-4-trifluoromethylanilines,methods of preparing the same and their use for preparation of corresponding herbicidal phenylenediamine derivatives - Google Patents

Description

Hovel iJ-Ealo-2,6^1inltro-4-trifluoromethyl anilines ass*- methods of preparing the same and their use for preparation of corresponding herblcidal phonHenediamine derivatives o'a&y n O^a^a^esfia^ ^JO nnVw ruana οσιο^ onaanl w*© 35690/3 This Invention relates to novel 3-halo-2,6~d1n1tro~4-tr1-fluoromethyl anilines of the formula NO, NO, CF, wherein X 1s halogen, Rj is hydrogen, alkyl, alkenyl or alkynyl optionally substituted by halogen or hydroxy or alkoxy groups, and Rg 1s alk t;, alkenyl or alkynyl optionally substituted by; 'halogen or hydroxy o alkoxy groups; or either R1 or R21s a cycloalkyl group; or R^ and Rg together are each an alkyl ene group linked with the nitrogen atom to form a saturated heterocyclic radical. These compounds are In themselves herblcldally active, and can be used as ntermediates for making herblc dal d1n1trophenylened1 amines of the formula as disclosed 1n our British Patent No. 1 ,268,584.

Typical Examples of hydrocarbon groups represented by Rj and as defined above, are the lower alkyl, lower alkenyl, and lower alkynyl groups having up to about 6 carbon atoms, ncluding the cyclic analogues thereof, as well as is halo, hydroxy, and lower alkoxy derivatives thereof. ethyl, 2-bromoethyl , 2-methoxyethyl , 3-ethoxypropyl , 2-2-dimethoxyethyl, 2-chloroallyl, 3-chloropropyl, 4-hydroxy-2-butynyl, 1-methyl-2-methoxyethyl, 2-brcmo-allyl propynyl^ 4-chloro-2-butenyl , 3-bromo-l-butenyl, 3-iodo-2-pentenyl , 4-chloro-2-butynyl , cyclohexyl, cyclopropyl, cyclobutyl, cyclohexenyl, and the like.

Also, as described above, R -R can represent a frag ment of 1 & a ring of which the amino nitrogen is a part such as illustrated by the structure -N Z in which Z is an alkylene group having from about 2 to 6 carbon atoms in the chain, and optionally containing other atoms such as oxygen and nitrogen. Examples of such linkages include the dimethylene, trimethylene, tetraraethylene, diethyleneoxy, diethyleneimino, and hexa-methylene groups.

Representative examples of compounds provided by this invention are N-ethyl-3-chloro-2, 6-dinitro-4-trifluoromethylaniline N, N-dipropyl-3-chloro-2, -dinitro-4-trifluoromethylaniline N, N-dimethylene-3-chloro-2, 6-dinitro-4-trifluoromethylaniline N, N-diethyl-3-bromo-2, -dinitro-4-trifluoromethylaniline N-allyl-3-chloro-2, 6-dinitro-4-trifluoromethylaniline N- (3-chloropropyl)-3-chloro-2, 6-dinitro-4-trifluoromethylanil ne N-sec-butyl-3-fluoro-2, 6-dinitro-4-trifluoromethylaniline N-( l-methyl-2-methoxyethyl )-3-chloro-2, 6-dinitro-4-trifluoromethylaniline NtN-pentamethylene-3-chloro-2, 6-dinitro-4-trifluoromethylaniline N-n-hexyl-3-chloro-2, 6-dinitro-4-trifluoromethylaniline N-methyl-N-propyl-3-bromo-2,6-dinitro-4-trifluoromethylaniline N,N-diallyl-3-fluoro-2, 6-dinitro-4-trifluoromethylaniline N-methyl-N-cyclopentyl-3-chloro-2, 6-dinitro-4-trifluoromethylaniline N-propynyl-3-bromo-2, 6-dinitro-4-trifluororaethylaniline N-(2-hydroxyethyl)-N-methyl-3-chloro-2, 6-dinitro-4-trifluoro- methylaniline The compounds of this invention are either crystalline solids or high-boiling liquids. Generally, they are only slightly soluble in water and are moderately soluble in the usual organic solvents such as ethanol, acetone, and benzene. The compounds are readily prepared by reaction of an amine with a 2, 4-dihalo-3, 5-di.nitrobenzotrifluoride according to the equation in which X is halogen, and R and R have the significance previously assigned.

Thus the invention provides a compound of the formula CF. wherein X is halogen, R^ is hydrogen, alkyl, alkenyl, or alkynyl, and R is alkyl, alkenyl, or alkynyl.

The reaction is advantageously carried out in the presence of a solvent such as a hydrocarbon or alkohol. An excess of amine, such as about two moles of amine for each mole of the benzotrifluoride, is preferably employed. The second mole of amine neutralizes the by-products hydrogen halide as it is formed. Alternatively, a tertiary amine can be used as an acid neutralizing agerit. The reaction can be carried out in a sealed reaction vessel such as an autoclave or at atmospheric pressure in the presence of a solvent. A reaction temperature in the range of from about 20° to about 100°C. preferably is employed to give good yields of the desired product and a satisfactory rate of reaction. The byproduct amine hydrohalide is removed by washing with water or by filtration from the solvent in which it is insoluble. The desired product is isolated and purified by well known procedures such as by recrystallization.

The following Examples describe preparation of representative compounds of this invention, but it is to be understood that the invention is not to be limited to the specific Examples given.

Compounds of this invention may be reacted in equimolar amounts with ammonia or a primary or secondary amine to form herbicidal trifluoromethyl dinitrophenylenediamines.

EXAMPLE I N,N-di-n-propyl-3-chloro-2, 6-dinitro-4-trifluoromethylaniline A heavy walled glass teaction tube of approximately 50 nil« capacity was charged with 7·0 grams (0.023 mole) of 2, -dichloro-3» 5-di-nitrobenzotrifluoride, 4.64 grams (0,0458 mole) of di-n-propylamine and 40 ml. of absolute ethanol. The tube was sealed and heated in an oil bath at 94°-99°C. for 98 hours. The cooled reaction mixture was then evaporated to dryness to give an oily residue which was extracted with boiling diethyl ether. The insoluble di-n-propylamine hydrochloride was removed by filtration and washed with additional ether. The combined ether filtrates were evaporated to give an oily orange residue which was dissolved in 100 ml. of absolute ethanol and decolorized with activated charcoal. The ethanol and volatiles were removed by evaporation under EXAMPLE II N-sec-butyl-3-chloro-2, 4-dinitro-6-trifluoromethylaniline To a stirred mixture of 20 g. (O i 0655 mole) of 2, 4-dichloro-3, 5-dinitrobenzotrifluoride and 150 ml. of absolute ethanol was added 9.58 9 · (0.131 mole) of sec-butylamine, dropwise, over a period of about 15 minutes. The resultant solution was refluxed for 2 hours and the ethanol then removed by distillation under reduced pressure. The solid yellow residue was triturated with 300 ml. water to dissolve the sec-butylamine hydrochloride. The water insoluble product was isolated by filtration, washed with water, and then dissolved in 600 ml. of refluxing 95% ethanol. Upon cooling, the product crystallized.

Filtration gave 20,4 g. of a yellow crystalline solid, melting at 90.5°-91.5°C.

EXAMPLE III N, N-diethyleneoxy-3-chloro-2, 6-dinitro-4-tri luoromethylaniline The compound was prepared by reacting 2, -dichloro-3, 5-dinitrobenzotrifluoride with morpholine in an ethanol-dioxane solvent mixture, o After recrystallxzation from ethanol, the compound melts at 125.5 -126.5°C.

EXAMPLE IV N- ( 2-bromoethyl ) -3-chloro-2, 6-dinitro-4-trifluoromethylaniline The compound was prepared by reacting 2, -dichloro-3, 5-dinitrobenzotrifluoride with 2-bromoethylamine in an ethanol solution. The resultant product melted at 88°-92°C.

EXAMPLE V N- ( 2-chloroallyl ) -3-chloro-2, 6-dinitro-4-trifluoromethylaniline The compound was prepared by reacting 2-chloroallylamine with 2, -dichloro-3, 5-dinitrobenzotrifluoride in etknaol. After recrystalliza-tion from ethanol, the compound melts at 78°-80°C.

EXAMPLE VI N-cyclopropyl-3-chloro-2, 6-dinitro-4-trifluoromethylaniline The compound was prepared by reacting cyclopropylamine with 2, -dichloro-3, 5-dinitrobenzotrifluoride in cyclohexane to give the product having a melting point of 86°-87°C, EXAMPLE VII N-(2-methoxyethyl )-3-chloro-2,6-dinitro-4-trifluoromethylaniline The compound was preapred by reacting 2-methoxyethylamine with 2, -dichloro-3, 5-dinitrobenzotrifluoride in cyclohexane to give the product melting at 106.5°-107.5°C.

EXAMPLE VIII N-propynyl-3-chloro-2, 6-dinitro-4-trifluoromethylaniline The compound was prepared by reacting propargylamine with 2.4-dichloro-3j 5-dinitrobenzotrifluoride in cyclohexane to give the product melting at 86°-87°C.

The 2, 4-dihalo-3t 5-dinitrobenzotrifluoride starting materials are readily prepared by nitration of the corresponding 2, 4-dihalobenzo-trifluoride with a mixture of fuming nitric and fuming sulphuric acids at a temperature below 90°C, preferably in the range 60-80°C.

We give next an example of the preparation of a 2,4-dihalo- 3.5-dinitrobenzofluoride which is a starting material for compounds of the present invention, and thenan example of the conversion of a compound of.thxs invention to a herbicidal trifluoromethyl-2, 4-dinitro-l, 3-phenylene diamine.

EXAMPLE IX (Starting material) 2, 4-dichloro-3i 3-dinitrobenzotrifluoride Fuming sulphuric acid (600 ml.) containing 30-33% free SO was 3 stirred in a two-litre, three-necked flask immersed in an ice bath.

Fuming 90% nitric acid (585 ml.) was added feilowed by 148.8 grams (Ο.692 mole) of 2, 4-dichlorobenzotrifluoride. This stirred slurry then was heated to 76°C. and held at 76 +_ 1°C, for 96 hours; The mixture was cooled and the acid was drained from the crust of crystalline product. Water ( 1000 ml.) was added to the broken up solid and the stirred slurry extracted with 00 ml. of toluene. The toluene solution, with another 500 ml. of toluene was added, was washed successively with water ( 500 ml.), twice with 500 ml. of a 5% sodium bicarbonate solution, and finally with water ( 500 ml.). Removal of the toluene by evaporation at reduced pressure and drying overnight gave 166.6 grams (79%) of the desired 2, 4-dichloro-3, 5-dinitrobenzotrifluoride, m.p. 67°-72°C. After o o recrystallizatxon from ethanol the material melts at 74 -75 C. 2, 4-Dibromo-3, -dinitrobenzotrifluoride is prepared in a similar manner by reaction of 2, 4-dibromobenzotrifluoride in place of 2, 4-dichlorobenzotrifluoride.

The compounds of this invention are useful as intermediates for the preparation of herbicidal trifluoromethyl-2, 4-dinitro-l, 3-pheriylene- diamine compounds as described in our (fr>11 n 15 76.) . , The phenylenediamines are prepared according to the following equation in which X, R and R have the significance previously assigned, and R i. 3 and R^ are each a hydrogen atom or an alkyl, alkenyl or alkynyl group.- In preparation of these herbicides, the amine or ammonia is reacted with the compound of this invention either in a sealed reaction vessel such as an autoclave or at atmospheric pressure. The by-products hydrogen halide is neutralized by use of excess amine or a tertiary amine. Preferably a solvent such as an alcohol or hydrocarbon is employed to provide control o of the reaction temperature which can be in the range from about 20 to about 120°C. The by-product amine hydrohalide is removed by washing with water or by filtration when a solvent is employed in which the hydrohalide is insoluble. The desired 1 , 3-phenylenediamine is isolated and purified by well known procedures.

The following Examples illustrates the use of a compound of this invention as intermediate for preparing the herbicidal phenylene-diamine compounds.

EXAMPLE X 3 3 N ,N -di-n-propyl-2, -dinitro-6-trifluoromethyl-1 , 3-phenylenediamine A glass reaction tube was charged with 4.0 grams ( 0.0108 mole) of N, N-di-n-propyl-3-chloro-2, 6-dinitro-4-trifluoromethylaniline, .82 grams (0.0237 mole) of 6.95% ethanolic ammonia and 35 ml. of ethanol. The tube was sealed and heated in an oven at 100°C, for 68 hours. The contents of the tube were cooled and the ethanol removed by evaporation. Water was added to the solid orange residue to dissolve the ammonium chloride and the insoluble product was separated by filtration. The product was dissolved in refluxing 95% ethanol. Upon cooling, orange needles and a yellow powder crystallized. The yellow powder was identified as 2, 4-dinitro-6-trifluoromethyl- 1 , 3-phenylenediamine and was separated from the desired product by filtration after extracting with boiling hexane. The desired product dissolved in the hexane and was isolated from the filtrate by evaporation of the hexane. The residue was recrystallized from 95% ethanol to give orange needles, m.p. 124°-125°C . Analysis; Calculated: N = 15.99 Found: N = 16.00 are especially useful as selective herbicides for controlling weeds in the presence of desirable crops such as corn^ rice, cotton, and soybeans.

The monohalo monoamino compounds of this invention have herbicidal activity in their own right in addition to being useful as intermediates for preparation of the diamino herbicides. For example, when applied as a pre- or post-emergence treatment at a rate of from about 5 to 20 pounds per acre, the compounds give excellent control of grassy weeds such as foxtail, water grass, crabgrass, and millet.

Claims (13)

356.90/4 \ Claims :

1. A compound of the formula wherein X is halogen, ^ is hydrogen, alkyl, alkenyl or alkynyl optionally substituted by halogen or hydroxy or alkoxy groups, and R2 is alkyl, alkenyl or alkynyl optionally substituted by halogen or hydroxy or alkoxy groups! or either R^ or Rj is a cycloalkyl group; or R^ and together are each an alkylene group linked with the nitrogen atom to form a saturated heterocyclic radical.

2. A1 compound according to claim 1, in which X is chlorine or bromine.

3. A compound according to claim 1 or 2, in which R^ and R2 are each lower (C^_g) alkyl.

4. A compound according to claim 1 or 2, in which ^ is hydrogen and R2 is lower (C^g) alkyl.

5. N,N-diethyl-3-chloro-2,6-dinitro-4-trifluoromethylaniline.

6. N-Bec-buty1-3-chloro-2 , 6-dinitro-4-trifluoromethylani¾ine.

7. A compound according to claim 1, substantially as herein described.

8. A method for preparing a compound of formula 35690/4, as defined in claim 1, 2, 3 or 4, which comprises reacting the corresponding 2,4-dihalo-3,5-dinitrobenzotrifluoride with an a£ amine of the formula in which is hydrogen, aikyl, alkenyl or alkynyl optionally substituted by halogen or hydroxy or alkoxy groups, and R2 is aikyl, alkenyl or alkynyl optionally substituted by halogen or hydroxy or alkoxy groups; or either R^ or is a cycloalkyl group; or R^ and Rg together are each an alkylene group linked with the nitrogen atom to form a saturated heterocyclic radical.

9. A method according to claim 8, in which about two moles of said amine are reacted with about one mole of said 2,4-dihalo-3, 5-dinitro-benzotrifluoride.

10. The method according to claim 7, in which X is bromine or chlorine.

11. A method of preparing a compound according to claim 1, substantially as hereinbefore described.

12. A halodinitrotrifluoromethylaniline when prepared by a process according to claim 8, 9, 10 or 11.

13. A method of preparing a herbicidal compound of the formula : wherein and R^ are as defined in claim 1 and R^ and R^ are each a hydrogen dom or an alkyl, alkenyl or alkynyl group, which comprises reacting a compound according to any one of claims 1 to 8 and 13, with ammonia or an amine of formula NR„R.. 3 ¾ .