Processes for the preparation of benzotriazole UV absorbers

A process for preparing a compound of formula (I)

• which process comprises
• diazotizing a perfluoroalkyl substituted o-nitroaniline of formula (II)
• using concentrated sulfuric acid and an alkali metal nitrite or nitrosylsulfuric acid to form the corresponding diazonium salt of formula (III)
• coupling said diazonium salt with a phenol of formula (IV)
• to form a monoazobenzene compound of formula (V)
• reducing the monoazobenzene intermediate of formula (V) to the corresponding 2H-benzotriazole compound of formula (I) by conventional reduction means;
• wherein
• G1 is hydrogen or chloro,
• G2 is perfluoroalkyl of 1 to 12 carbon atoms,
• E1 is hydrogen, straight or branched chain alkyl of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 24 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms;
• or E1 is alkyl of 1 to 24 carbon atoms substituted by one or two hydroxy groups,
• E2 is straight or branched alkyl chain of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms;
• or E2 is said alkyl of 1 to 24 carbon atoms or said alkenyl of 2 to 18 carbon atoms substituted by one or more —OH, —OCOE11, —OE4, —NCO, —NHCOE11 or —NE7E8, or mixtures thereof, where E4 is straight or branched chain alkyl of 1 to 24 carbon atoms or alkenyl of 2 to 18 carbon atoms;
• or said alkyl or said alkenyl interrupted by one or more —O—, —NH— or —NE4— groups or mixtures thereof and which can be unsubstituted or substituted by one or more —OH, —OE4 or —NH2 groups or mixtures thereof;
• or E2 is —(CH2)m—CO—E5;
• E5 is OE6 or NE7E8, or
• E5 is —PO(OE12)2, —OSi(E11)3 or —OCO—E11, or straight or branched chain C1-C24alkyl which can be interrupted by —O—, —S— or —NE11 and which can be unsubstituted or substituted by —OH or —OCO—E11, C5-C12cycloalkyl which is unsubstituted or substituted by —OH, straight chain or branched C2-C18alkenyl which is unsubstituted or substituted by —OH, C7-C15aralkyl, —CH2—CHOH—E13 or glycidyl,
• E6 is hydrogen, straight or branched chain C1-C24alkyl which is unsubstituted or substituted by one or more OH, OE4 or NH2 groups, or —OE6 is —(OCH2CH2)wOH or —(OCH2CH2)wOE21 where w is 1 to 12 and E21 is alkyl of 1 to 12 carbon atoms,
• E7 and E8 are independently hydrogen, alkyl of 1 to 18 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, straight or branched chain C3-C18alkyl which is interrupted by —O—, —S— or —NE11—, C5-C12cycloalkyl, C6-C14aryl or C1-C3hydroxylalkyl, or E7 and E8 together with the N atom are a pyrrolidine, piperidine, piperazine or morpholine ring, or
• E5 is —X—(Z)p—Y—E15
• wherein
• X is —O— or —N(E16)—,
• Y is —O— or —N(E17)—,
• Z is C2-C12-alkylene, C4-C12-alkylene interrupted by one to three nitrogen atoms, oxygen atoms or a mixture thereof, or is C3-C12-alkylene, butenylene, butynylene, cyclohexylene or phenylene, each substituted by a hydroxyl group,
• m is zero, 1 or 2,
• p is 1, or p is also zero when X and Y are —N(E16)— and —N(E17)—, respectively,
• E15 is a group —CO—C(E18)═C(H)E19 or, when Y is —N(E17)—, forms together with E17 a group —CO—CH═CH—CO—, wherein E18 is hydrogen or methyl, and E19 is hydrogen, methyl or —CO—X—E20, wherein E20 is hydrogen, C1-C12-alkyl or a group of the formula
• wherein the symbols E1, G2, X, Z, m and p have the meanings defined above, and E16 and E17 independently of one another are hydrogen, C1-C12-alkyl, C3-C12-alkyl interrupted by 1 to 3 oxygen atoms, or is cyclohexyl or C7-C15aralkyl, and E16 together with E17 in the case where Z is ethylene, also forms ethylene,
• E11 is hydrogen, straight or branched chain C1-C18alkyl, C5-C12cycloalkyl, straight or branched chain C2-C18alkenyl, C6-C14aryl or C7-C15aralkyl,
• E12 is straight or branched chain C1-C18alkyl, straight or branched chain C3-C18alkenyl, C5-C10cycloalkyl, C6-C16aryl or C7-C15aralkyl, and
• E13 is H, straight chain or branched C1-C18alkyl which is substituted by —PO(OE12)2, phenyl which is unsubstituted or substituted by OH, C7-C15aralkyl or —CH2OE12,
• with the proviso that when concentrated sulfuric acid and alkali metal nitrite are used, E1 and E2 are alkyl of 1 to 4 carbon atoms, or E1 can also be hydrogen.