Herbicidal Derivatives of 5-Phenoxy-4(3h)-Quinazolinone-1-Oxide

Herbicidal 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid and salts thereof, and various herbicidal derivatives of these compounds have been proposed including alkyl and cycloalkyl esters, alkylthio esters, phenyl ester, alkyl and dialkyl amido and benzoyl chloride forms. U.S. Patents which describe such compounds and the like include U.S. Pat. Nos. 3,652,645; 3,784,635; 3,873,302; 3,983,168; 3,907,866; 3,798,276; 3,928,416; and 4,063,929.

This invention provides certain herbicidal compounds of the formula: ##STR2## where: (i) Y.sub.1 is C-H or N;

(ii) Y.sub.2 is C-X.sub.3 or N, provided that Y.sub.1 is not N when Y.sub.2 is C-X.sub.3 ; and

(iii) X.sub.1, X.sub.2, X.sub.3, R.sub.1 and R.sub.2 are groups which are capable of being incorporated into formula I and which collectively impart herbicidal activity thereto.

Examples of the groups X.sub.1, X.sub.2, X.sub.3, R.sub.1 and R.sub.2 are as follows:

X.sub.1 and X.sub.2 may be the same or different and may be selected from the group consisting of halo (e.g., Cl, Br and F), cyano, nitro and trihalomethyl(e.g., CF.sub.3);

X.sub.3 may be H or any of the groups exemplified above for X.sub.1 and X.sub.2 ;

R.sub.1 and R.sub.2 may be the same or different and may be hydrogen or a hydrocarbyl group (substituted or unsubstituted, e.g., having from 1 to 12 carbon atoms).

More particular examples of the R.sub.1 hydrocarbyl groups include C.sub.1 -C.sub.5 alkyl, alkenyl, aryl, aralkyl all of which may be optionally substituted with hydroxyl, alkoxy, cyano, halo (e.g., cl, Br and F) or COO alkyl. More particular examples of R.sub.2 include C.sub.1 -C.sub.3 alkyl and trifluoromethyl.

A preferred form of compounds of formula I is represented by the formula ##STR3##

The following compound was prepared: ##STR4## 5-(2-chloro-4-trifluoromethylphenoxy)-2-nitrobenzamide (7.2 gm, 0.02 mole) was added to a stirred solution of SnCl.sub.2 2H.sub.2 O (10.3 gm, 0.066 mole) in glacial acetic acid (100 ml) saturated with HCl gas. After 3 hours the reaction mixture was poured on crushed ice (300 gm). The precipitated product was filtered, washed with water, and crystallized from acetonitrile. 2.07 gm of product was obtained having m.p. 195.degree.-198.degree..

II and III may be prepared similarly ##STR5##

Preparation of IV ##STR6##

Compound I (2.0 gm) was refluxed in triethyl or thoformate for 1 hour. The resulting clear solution was cooled to -5.degree. overnight. The crystalline solid which separated was filtered and washed with ether. Yield 1.0 gm of material having m.p]. 178.5.degree.-180.degree..

IR(KBr) 3420, 3170, 3020, 2900, 1670, 1610, 1480 cm.sup.-1.

Compounds V and VI are prepared similarly ##STR7##

Compounds VII-IX may be prepared from the corresponding quinoxalinones by reaction with a 10% excess of 30% H.sub.2 O.sub.2 in trifluoroacetic acid at 50.degree.. The products are obtained by evaporation of solvent and crystallization from a suitable solvent. ##STR8## VII: R=H VIII: R=CH.sub.3

IX: R=CH.sub.2 CO.sub.2 CH.sub.3

The compounds of this invention can be applied in various ways to achieve herbicidal action. They can be applied per se, but may be applied as the toxic components in pesticidal compositions of the compound and a carrier. These compositions may be applied directly to the soil and often incorporated therewith. The compositions can be applied as granulars or dusts; as liquid sprays, or as gas-propelled sprays and can contain, in addition to a carrier, additives such as emulsifying agents, binding agents, gases compressed to the liquid state, odorants, stabilizers, and the like. A wide variety of liquid and solid carriers can be used. Non-limiting examples of solid carriers include talc, bentonite, diatomaceous earth, pyrophyllite, fullers earth, gypsum, flours derived from cotton seeds and nut shells, and various natural and synthetic clays having a pH not exceeding about 9.5. Non-limiting examples of liquid carriers include water, organic solvents such as alcohols, ketones, light oils, and medium oils and vegetable oils such as cottonseed oil. In practice, herbicidal application is measured in terms of pounds of herbicide applied per acre. The compounds of this invention are effective herbicides when applied in herbicidal amounts, e.g., at rates between about 0.03 pound and about 10 pounds per acre.

Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the appended claims.