A process for preparing a 1-aryl-pyrazole compound of formula: wherein: R 1b is hydrogen, cyano, halogen, R 8b, formyl, -CO 2 H, -C R 8b, -C OR 8b,-C NR 9b R 10b or -C NH 2; R 2b is R 8b or -S m R 11b; R 3b is alkyl, haloalkyl, hydroxyalkyl, cycloalkyl, halocycloalkyl, alkenyl, alkynyl, aryl, heterocyclyl, heteroaryl, R 8b O, R 8b S or R 8b C CH 2 - wherein each alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocyclyl or heteroaryl group may optionally be substituted by one or more of halogen, hydroxy, alkoxy, alkoxyalkoxy, amino, alkylamino, dialkylamino, nitro, cyano or -C NH 2; R 4b, R 5b, R 7b and R 13b are each independently hydrogen, halogen, alkyl, haloalkyl, cyano or nitro; R 6b is halogen, alkyl, haloalkyl, alkoxy, haloalkoxy, cyano, nitro, -C R 12b, - S n R 12b or SF 5; W is nitrogen or C-R 13b; R 8b is alkyl, haloalkyl, hydroxyalkyl, cycloalkyl, halocycloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, aryl, heterocyclyl or heteroaryl; R 9b and R 10b are independently hydrogen, alkyl, haloalkyl, hydroxy or alkoxy; R 11b is alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, cycloalkyl or halocycloalkyl; R 12b is alkyl or haloalkyl; m is 0, 1 or 2; and n is 0, 1 or 2; which comprises: (i) reacting a compound of formula: wherein R 1b, R 2b, R 4b, R 5b, R 6b, R 7b and W are as defined above for the compound of formula and Q is iodo, bromo, chloro or a haloalkylsulfonate group; with a compound of formula (IIc) or (IId): wherein R, R 1d, R 2d and R 3d are independently alkyl, haloalkyl, cycloalkyl, halocycloalkyl, alkenyl, alkynyl, aryl, heteroaryl or heterocyclyl, wherein each alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl or heterocyclyl group may optionally be substituted with one or more halogen, hydroxy, alkoxy, alkoxyalkoxy, amino, alkylamino, dialkylamino, nitro, cyano or -C NH 2 groups; M is MgX, ZnX, RZn, BY 2 or BF 3; X is iodo, bromo or chloro; and Y is OH or alkoxy, or each Y may be an alkoxy group which is part of a glycol derivative Y-(CR"R'") a -Y where R" and R'" are independently hydrogen or C 1 -C 3 alkyl and a is 2, 3 or 4; or reacting the compound of formula with R 8b OH, R 8b SH or an enolate anion R 8b C CH 2 -, wherein R 8b is as defined above for the compound of formula; in the presence of a transition metal catalyst to form the compound of formula; (ii) wherein if R 1b in the compound of formula is -C OR 8b or -C NR 9b R 10b, optionally converting the -C OR 8b or -C NR 9b R 10b groups to cyano, hydroxyalkyl, aminoalkyl, dialkylaminoalkyl, formyl, -C R 8b or -C NH 2, wherein R 8b, R 9b and R 10b are as defined above for the compound of formula, via functional group modification; and (iii) wherein if R 2b is -S m R 11b, optionally oxidizing the group -S m R 11b where m is 0 or 1, to form the compound of formula; wherein the sequence of steps ii) and iii) may be interchanged. R 1b is hydrogen, cyano, halogen, R 8b, formyl, -CO 2 H, -C R 8b, -C OR 8b,-C NR 9b R 10b or -C NH 2; R 2b is R 8b or -S m R 11b; R 3b is alkyl, haloalkyl, hydroxyalkyl, cycloalkyl, halocycloalkyl, alkenyl, alkynyl, aryl, heterocyclyl, heteroaryl, R 8b O, R 8b S or R 8b C CH 2 - wherein each alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heterocyclyl or heteroaryl group may optionally be substituted by one or more of halogen, hydroxy, alkoxy, alkoxyalkoxy, amino, alkylamino, dialkylamino, nitro, cyano or -C NH 2; R 4b, R 5b, R 7b and R 13b are each independently hydrogen, halogen, alkyl, haloalkyl, cyano or nitro; R 6b is halogen, alkyl, haloalkyl, alkoxy, haloalkoxy, cyano, nitro, -C R 12b, - S n R 12b or SF 5; W is nitrogen or C-R 13b; R 8b is alkyl, haloalkyl, hydroxyalkyl, cycloalkyl, halocycloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, aryl, heterocyclyl or heteroaryl; R 9b and R 10b are independently hydrogen, alkyl, haloalkyl, hydroxy or alkoxy; R 11b is alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, cycloalkyl or halocycloalkyl; R 12b is alkyl or haloalkyl; m is 0, 1 or 2; and n is 0, 1 or 2; (i) reacting a compound of formula: wherein R 1b, R 2b, R 4b, R 5b, R 6b, R 7b and W are as defined above for the compound of formula and Q is iodo, bromo, chloro or a haloalkylsulfonate group; with a compound of formula (IIc) or (IId): wherein R, R 1d, R 2d and R 3d are independently alkyl, haloalkyl, cycloalkyl, halocycloalkyl, alkenyl, alkynyl, aryl, heteroaryl or heterocyclyl, wherein each alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl or heterocyclyl group may optionally be substituted with one or more halogen, hydroxy, alkoxy, alkoxyalkoxy, amino, alkylamino, dialkylamino, nitro, cyano or -C NH 2 groups; M is MgX, ZnX, RZn, BY 2 or BF 3; X is iodo, bromo or chloro; and Y is OH or alkoxy, or each Y may be an alkoxy group which is part of a glycol derivative Y-(CR"R'") a -Y where R" and R'" are independently hydrogen or C 1 -C 3 alkyl and a is 2, 3 or 4; or reacting the compound of formula with R 8b OH, R 8b SH or an enolate anion R 8b C CH 2 -, wherein R 8b is as defined above for the compound of formula; in the presence of a transition metal catalyst to form the compound of formula; (ii) wherein if R 1b in the compound of formula is -C OR 8b or -C NR 9b R 10b, optionally converting the -C OR 8b or -C NR 9b R 10b groups to cyano, hydroxyalkyl, aminoalkyl, dialkylaminoalkyl, formyl, -C R 8b or -C NH 2, wherein R 8b, R 9b and R 10b are as defined above for the compound of formula, via functional group modification; and (iii) wherein if R 2b is -S m R 11b, optionally oxidizing the group -S m R 11b where m is 0 or 1, to form the compound of formula;