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US 2003/0191341 A1Published application
Chemical process
AssigneeNone recorded
InventorsStephen Martin Brown, James Peter Muxworthy
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AssigneeNone recorded
InventorsStephen Martin Brown, James Peter Muxworthy
Estimating the term…
A process for the preparation of a compound of general formula I: 1 wherein: R1 is hydrogen or C1-C6 alkyl, C2-C6 alkenyl or C2-C6 alkynyl (any of which may optionally be substituted with one or more substituents selected from halogen and OH) or COOH, COH, COOR4, COR6,CONR4R5 or CONHSO2R4; R4 and R5 are each independently hydrogen or C1-C4 alkyl optionally substituted with one or more halogen atoms; R6 is a halogen atom or a group R4; R2 is hydrogen or halo; R3 is C1-C4 alkyl, C2-C4 alkenyl or C2-C4 alkynyl, any of which may optionally be substituted with one or more halogen atoms, or halo; the process comprising reacting a compound of general formula II: 2 wherein R1, R2 and R3 are as defined for general formula I; with a nitrating agent comprising nitric acid or a mixture of nitric and sulphuric acids in the presence of an organic solvent and in the presence of acetic anhydride, characterised in that the molar ratio of acetic anhydride to compound of general formula I is from about 1:1 to 3:1.
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A process for the preparation of a compound of general formula I:
Dependencies are inferred from the claim text.
From the US filing history. Foreign family members aren’t listed.
Backward citations are indexed for grants only.
Preparation of nitro compounds: by substitution of hydrogen atoms by nitro groups
Of amides of sulfonic acids: by reactions not involving the formation of sulfonamide groups
Acyclic or carbocyclic compounds
Term end not estimated
The present invention relates to a process for nitration and, in particular to a process for nitrating diphenyl ether compounds which are useful as herbicides or as intermediates in the synthesis of herbicides.
EP-A-0022610 relates to herbicides of the formula: 3
wherein X and Y may be H, F Cl, Br, CF3, OCF2CHZ2 (Z=Cl, Br, F), OCH3, CN, CO2R (R=lower alkyl), C6H5, O-alkyl, NO2 or SO2 lower alkyl;
General Method for Nitration of 3-(2-chloro-α,α,α-trinfluoro-4-tolyloxy)benzoic Acid in Dichloromethane to Yield Acifluorfen
Nitration
Acetic anhydride (see Tables I and II for amounts) was added to 3-(2-chloro-α,α,α-trifluoro-4-tolyloxy)benzoic acid (I, R1 is COOH, R2 is chloro, R3 is trifluoromethyl) (20 g, 0.063 mol) in dichloromethane (54 g, 0.635 mol) and the mixture stirred and heated to 40° C. to dissolve the starting material. The mixture was then cooled to the appropriate reaction temperature (during which time any crystallisation of the starting material was observed). Mixed acid (13 g, 0.069 mol) was added dropwise over a period of 2 hours and the reaction monitored by HPLC for the completion of the reaction. Further additions of Mixed acid were made to reduce the level of starting material to about 1 pph.