Patent Publication Number: US-3880869-A

Title: Dyes of the benzopyrane series

Description:
United States Patent [1 1 Scheuermann et al.  
 [ Apr. 29, 1975 DYES OF THE BENZOPYRANE SERIES [75] lnventors: Horst Scheuermann, Ludwigshafen;  
 Wolfgang Mach, Hockenheim; Dielmar Augart, Ludwigshafen. all of Germany [73] Assignee: BASF Alniengesellschall, Ludwigshafen, Germany 221 Filed: Nov. 1,1973  
  2| Appl. N0.;411,7s9  
 [30] Foreign Application Prioriiy Data Nov. 2. I972 Germany 2253538 June 2. 1973 Germany 2328l46 [52] US. Cl. 260/296 P: 8/179; 260/240 1&#39;,  
 {56] Relerences Cited OTHER PUBLICATIONS Chemical Abstracts, Sixth Collective Index (vols.  
 51-55, I957 to l96l page I660 s (1964).  
 Dean et al.. J. Chem. Soc. 1957, pp. 3497 to 3510.  
 Primary Examiner-John D. Randolph Attorney, Agent, or Firm.lohnston, Keil, Thompson &amp; Shurtleff [57] ABSTRACT Dyes of the formula:  
 containing a benzopyrane system and a benzimidazole system. The dyes give extremely brilliant orange to red violet colorations of good fastness properties particularly in polyesters.  
 9 Claims, No Drawings DYES OF THE BENZOPYRANE SERIES The invention relates to dyes of the formula (I):  
  z FQZ Z2 N Z6 P B M&#34;) in which Z is unsubstituted or substituted alkyl or aralkyl;  
 Z and Z are hydrogen, unsubstituted or substituted alkyl, cycloalkyl, aralkyl or aryl&#39;,  
 Z and 2 together with the nitrogen form parts of a heterocyclic ring;  
 Z or 2 together with the nitrogen may form a saturated unsubstituted or substituted five-membered or six-membered ring condensed in ortho-position to the nitrogen;  
 Z is hydrogen, alkyl, alkoxy, halo, cyano, nitro, unsubstituted or substituted carbamoyl or sulfonamido or carbalkoxy;  
 m is I or 2;  
 n is zero or 1;  
 Z (when m is l is unsubstituted or substituted alkyl,  
 cycloalkyl, aralkyl or aryl, unsubstituted or substituted vinyl, alkoxy, phenoxy or amino and (when m is 2) methylene, ethylene, phenylene, OC, H O, OC=H OC,H -O,  
  l NH Z is hydrogen, carbalkoxy, nitro, cyano, alkylsulfonyl, unsubstituted or substituted carbamoyl, sulfonamide, phenyl, arylsulfonyl, benzimidazolyl, benzothiazoly, benzoxazolyl or quinazolinoyl;  
 Z is hydrogen or methyl; and  
 A is an anion.  
 The invention relates particularly to dyes of the formula (la):  
  2 R3 (fl a RE/N Y B in which 8&#39; is oxygen, imino or N-X-)7,R; R is methyl, ethyl, benzyl, B-hydroxyethyl, B-hydroxypropyl, B-cyanoethyl or B-carboalkoxyethyl; R is hydrogen, alkyl of one to four carbon atoms,  
 alkyl of one to four carbon atoms bearing cyano, alkoxy, chloro, bromo, carboxyl, carbalkoxy, carbamoyl or acetoxy as a substituent, cyclohexyl, benzyl, phenylethyl or phenyl;  
 R is hydrogen, alkyl of one to four carbon atoms, alkyl of one to four carbon atoms bearing cyano, alkoxy, chloro, bromo, carboxyl, carbalkoxy, carbamoyl or acetoxy as a substituent;  
 R and R together with the nitrogen form a fivemembered or six-membered heterocyclic ring;  
 R or R together with the nitrogen form a radical of the formula:  
 41-0-01! 4:11 N-CH-CH or N-CH-CH 2 t I 2 1 CH3 R R CH phenylsulfonyl, phenyl, benzimidazolyl or benzothiazolyl;  
  n IS zero or I; m is l or 2; and A is an anion. In addition to the radicals already individually specitied the following are examples of substituents:  
  For Z and Z or R and R methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, B-methoxyethyl, B-ethoxyethyl, B-acetoxyethyl, B-chloroethyl, B-carbomethoxyethyl, Bcarbethoxyethyl, B-carbobutoxyethyl, B-methoxypropyl, B-ethoxypropyl, B-methoxy-y-chloropropyl, or B-acetoxypropyl.  
 Examples of radicals which R and R may form to gether with the nitrogen are those of pyrrolidine, piperidine, morpholine, piperazine or N-methylpiperazine.  
  In addition to the examples already given, Z may be carbamoyl, Nmethylcarbamoyl, N-ethylcarbamoyl, N-butylcarbamoyl, N,N dimethylcarbamoyl, N,N-diethylcarbamoyl and the corresponding sulfonamido radicals, carbomethoxy, carbethoxy or carbobutoxy.  
 Examples of R other than those already specified are:  
 methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,  
  tert-butyl, chloromethyl, bromomethyl, methoxymethyl, ethoxymethyl, propoxymethyl, butoxymethyl, phenoxymethyl, methylmercaptomethyl, N-methylaminomethyl, N,N- dimethylaminomethyl, ethylmercaptomethyl, benzyl, carbomethoxymethyl, carbethoxymethyl, carbopropoxymethyl, cyanomethyl, acetylmethyl, B-chloroethyl, B-bromoethyl, B-hydroxyethyl, B-methoxyethyl, B-ethoxyethyl, B-butoxyethyl, B-phenoxyethyl, B-carbomethoxyethyl, B-carbobutoxyethyl, cyclohexyl, vinyl, B-phenylvinyl, B-(p-cyanophenyU-vinyl, B-(p-nitrophenyU-vinyl, methoxy, ethoxy, n-propoxy, isopropoxy, n&#39;butoxy, isobutoxy, tert-butoxy, B-methoxyethoxy, B-ethoxyethoxy, 4-tert-butylcyclohexoxy, cyclohexoxy, phenyl, o-chlorophenyl, p-chlorophenyl, 2,4- dichlorophenyl, 3,5-dichlorophenyl, mnitrophenyl, p-nitrophenyl, 2-chloro-5- nitrophenyl, o-methylphenyl, m-methylphenyl, p-  
 methylphenyl, o-methoxyphenyl, mmethoxyphenyl, p-methoxyphenyl, 3-nitro-4- methoxyphenyl, methylamino, ethylamino, npropylamino, isopropylamino, n-butylamino,  
  isobutylamino, tert-butylamino, cyclohexylamino, benzylamino, phenylamino, o-chlorophenylamino, m-chloropheriylamino, p-chlorophenylamino, p- (trifluoromethyl)-phenylamin0, pmethylphenylamino, o-methylphenylamino, mmethylphenylamino, p-methoxyphenylamino, omethoxyphenylamino or mmethoxyphenylamino. Examples of specific radicals for Z and Y in addition to those already specified are:  
 carbomethoxy, carbethoxy, carbobutoxy, carbo-B methoxyethoxy, carbo-B-ethoxyethoxy, methylsulfonyl, ethylsulfonyl, phenylsulfonyl, phenylsulfonyl bearing chloro, methyl, methoxy or alkoxy as a substituent, carbamoyl, N-alkylcarbamoyl, or N,N-dialkylcarbamoyl such as diethylcarbamoyl, ethylcarbamoyl, butylcarbamoyl, isooctylcarbamoyl, methylcarbamoyl, dimethylcarbamoyl, dipropylcarbamoyl, dibutylcarbamoyl or N-methyl-N-butylcarbamoyl, carboxyanilide, cyclohexylcarbamoyl, benzylcarbamoyl, carboxypyrrolidide, carboxypiperidide, carboxymorpholide, carboxypiperazide, carboxy-N-methylpiperazide and the corresponding sulfonamido radicals, phenyl, methylphenyl, chlorophenyl, methoxyphenyl, ethoxyphenyl, cyanophenyl, nitrophenyl, carbomethoxyphenyl, carbethoxyphenyl, benzimidazolyl, methylbenzimidazolyl, chlorobenzimidazolyl, N-methylbenzimidazolyl, N methylmethylbenzimidazolyl, benzothiazolyl or chlorobenzothiazolyl.  
  The same carbalkoxy radicals as for Y are suitable for R.  
  Examples of anions A are chloride, bromide, nitrate, thiocyanate, phosphate, sulfate, methosulfate,  
 ethosulfate, formate, acetate, p-toluenesulfonate, tetrachlorozincate 0r tetrafluoborate.  
  Dyes having particular technical significance are those having the formula (lb):  
  R5 /I fl (Ib) B R Y in which B is oxygen, imino or NX-R;  
 R is alkyl of one to four carbon atoms, preferably methyl or ethyl;  
 R is hydrogen, methyl, chloro or cyano; and  
 Y is cyanophenyl, cyano, phenylsulfonyl, carbomethoxy or carbethoxy; and  
 n, R, R, R, X and A have the above meanings.  
 Cyano is preferred for Y, Methyl, ethyl, benzyl, B-hydroxyethyl, B-hydroxypropyl, B-cyanoethyl and B-carbomethoxyethyl are preferred for R.  
  Unsubstituted or substituted phenylalkyl, phenyl, phenoxy and phenylamino are preferred for R. Suitable substituents are chloro, bromo, cyano, methyl, methoxy, ethyl, ethoxy, t-butyl and trifluoromethyl.  
  Dyes in which n is zero are preferred to those in which n is l.  
  The new fluorescent dyes have high brilliance and the hues are within the range from orange to violet. They are suitable for dyeing textile material of polyamides, cellulose esters, acrylonitrile polymers (n l and polyesters and also for the mass coloration of plastics.  
 Compounds of the formuia (I) may be prepared by reacting a compound of the formula (II):  
  H Z N N t Z XIX with a compound of the formula (III):  
  2? (III) and if necessary hydrolyzing, acylating and/or quaternizing the resulting compound of the formula (IV):  
  Z6 N Z1 m 25 O NH Z 5 Z, Z Z, Z and Z having the above meanings and A being cyano 0r carbalkoxy, particularly of two to five carbon atoms.  
  Compounds of the formula (ll) are known from DOS No. l,6l9,567.  
  Reaction of compounds (ll) and (III) is conveniently carried out in a solvent at a temperature of from 50 to 200C and preferably of from 100 to l 50C; an acid or preferably a base may be added for example in a catalytic amount.  
  Polar organic solvents are particularly suitable, examples being glycols and glycol ethers such as ethylene glycol or ethylene glycol monomethyl ether, chlorobenzene, dichlorobenzene, trichlorobenzene, dimethylformamide, N-methylpyrrolidone and also acetic anhydride with or without the addition of alkali metal acetate, or mixtures of solvents.  
  Examples of bases which may be used are: amines such as ethyldiisopropylamine, triethylamine, piperidine, pyridine. pyrrolidine or morpholine; sodium carbonate, potassium carbonate, sodium methylate and potassium methylate.  
  Examples of suitable acids are p-toluenesulfonic acid, benzenesulfonic acid, phosphoric acid, tetrafluoboric acid and hydrochloric acid. Compounds of formula (I) with n equal to zero may be quaternized by a conventional method for the production of quaternized compounds of the formula (I) with n equal to 1. Examples of quaternizing agents are the esters of strong acids such as methyl iodide, dimethyl sulfate, diethyl sulfate, methyl or ethyl p-toluenesulfonate, benzyl chloride, benzyl bromide, epoxides such as ethylene oxide or propylene oxide and acrylic acid derivatives such as acrylonitrile or methyl, ethyl or butyl acrylates.  
  Quaternization is conveniently carried out in a solvent such as a chlorohydrocarbon or hydrocarbon at elevated temperature. Examples of specific solvents are chloroform, ethylene chloride, chlorobenzene, odichlorobenzene, toluene and xylene.  
  An excess of quaternizing agent may be used instead of a solvent. Quaternization in water is also possible.  
  Hydrolysis of compounds of formula (IV) into the corresponding keto compounds may be carried out by the action of acid, particularly at elevated temperature.  
  Examples of acylating agents are acid halides, acid anhydrides, chlorocarbonates, isocyanates and ketenes. It is preferred to use isocyanates and diketene.  
  Acylation is conveniently carried out in a solvent in the presence of an inorganic or organic base, preferably an amine at a temperature of from 0 to l50C and preferably from to l00C.  
  Particularly suitable solvents are organic solvents, for example hydrocarbons such as benzene, toluene and xylene; halohydrocarbons such as 1,2-dichloroethane, chlorobenzene and dichlorobenzene; glycol ethers such as glycol diethyl ether and diethylene glycol diethyl ether, dioxane and tetrahydrofuran.  
  Examples of bases are: alkali metal carbonates such as sodium or potassium carbonate, alkali metal salts of lower fatty acids such as sodium or potassium acetate; and particularly organic bases such as triethylamine and pyridine. The organic base may serve at the same time as a solvent.  
  Production of compounds of the formula (I) in which R is acetonyl may be carried out by the reaction of a compound of formula (ll) with diketene.  
 Compounds of the formula (I) in which R is an un- Details of the reactions may be seen from the following Examples in which references to parts and percentages are by weight unless otherwise stated.  
 EXAMPLE I The dye of the formula:  
  fifi ]\N EXAMPLE 2 The dye of the formula:  
  9 CH S0 is obtained by heating 5.7 parts of the dye from Example l, 2.52 parts of dimethyl sulfate and I30 parts of odichlorobenzene for 1 hour at l20C, cooling to 20C, suction filtering the precipitate, washing it with 40 parts of petroleum ether and drying it. The yield is 6.5 parts and the melting point is 209C.  
 EXAMPLE 3 The dye of the formula:  
 is obtained by repeating Example 1 but using 4.5 parts of 3-benzimidazolyl-(2&#39;)-7-dimethylamino-2- iminocoumarin instead of 3-benzimidazolyl-(2&#39;)-7-diethylamino2-iminocoumarin. The yield is 5 parts and the melting point is 270 to 272C.  
 EXAMPLE 4 The dye of the formula:  
  9; e N n 1 cn so at (H c) N is obtained by heating 4.25 parts of the dye from Example 3 with 5.6 parts of dimethyl sulfate and I30 parts of o-dichlorobenzene for 3 hours at C, then cooling to 0C, suction filtering the deposited crystals, washing them with 10 parts of petroleum ether and drying them. The yield is 6 parts and the melting point is 220 to 225C.  
 EXAMPLE 5 The dye of the formula:  
 is obtained by boiling under reflux for l hour 3.2 parts of 3-(methyl)-benzimidazolyl-(2)-7-dimethylamino-2- iminocoumarin and 0.66 part of malononitrile in 50 parts of glycol monoethyl ether, then cooling to C, suction filtering, washing with l0 parts of ethanol and drying. The yield is 3 parts and the melting point is 312C.  
 EXAMPLE 6 The dye of the formula:  
 EXAMPLE 7 The dye of the formula:  
 is obtained by heating 3.8 parts of the dye of Example 6 in parts of o-dichlorobenzene and 2.25 parts of dimethyl sulfate for ninety minutes at C, then cooling to 20C, adding 50 parts of petroleum ether 4060, suction filtering the deposited substance and drying it. The yield is 4.l parts and the melting point is 245C with decomposition. l Dyes characterized by their substituents in the fol- O lowing Table are obtained by methods analogous to CN those described in the Examples.  
  B A 1/ N z 2 Ex. 2 2 Z Z Z Z n A Shade on polyester 8 NH CN C H C H5 CH3 0 red 9 0 CN CH C H C H CH 1 CH SO violet red 5 2 5 2 5 3V 5 a (polyacrylonitr&#39;ile) 10 NH CN C 11 H C H CH3 1 C H SO ViOle&#39;C red 11 NH CN CH C H (3 H C H CH 1 Br violet red 12 0 CN CH -CH OH C H C H CH3 1 Cl violet red 1} 0 CN CH -CH(OH)CH C H C H CH 1 1/2 ZnCl4 violet red 14 0 CN C H lCN C H C H CH 1 BF violet red 2 2 5 2 5 5 (polyacry lonitr&#39;i 1e:  
 15 0 CN C H CG CH C H C 14 CH 1 CH CD Violet red 16 0 CN C H CO C H C H5 C H CH 1 N0 violet: red  
 17 0 CN C H CO C H C H C H5 CH3 1 SNC violet: red  
 18 0 CN C H C H CH 0 red 19 NH CN H H H O red 20 NH CN C ll C H H O Ied Continued red red  
 red  
 red  
 red  
 red  
 red  
 red  
 red  
 red  
 red  
 red  
 red  
 red  
  d d d d d d e e e E E e P P P r. r T  
 CCCCC red Z x A Hum cn nolyustvr 11H I on Example Cntinued Hue on polyester Fxample red red  
 red  
 red  
 OCH-  
 red  
  1) H C O OCH red  
 red  
 red  
 A Hue on polyester Example red red  
 red  
 red  
 G E-I CHj red  
 red  
 red  
 - Continued Example Z 1 Z Z n A Hue on polyester 129 NH C H C H H O red 130 Q c 11 0 11 H 0 red N 151 NH Q C H C H ll 0 red 132 0 CN CH3 H o red 0 CN c 11 -CH(CH5)-CH2- H o red 134 0 CN on -CH(C6H5)-CH2- H 0 r&#39;ed 155 0 CN c 11 -CH(C6H5)-CH2- n o red 136 0 CN c n cn CQI-IQC&#39;N H o red 137 o H c 11 0 11 H 0 r&#39;ed Example 2 Z Z Z Z Z n A Hue on polyester 138 0 N02 C11 CH H o red 39 0 502N142 (3H5 CH3 H 0 red CH CH H 0 red 141 O H&#34; I CH CH3 H O Fed l 42 O SO -C&#39;H CH CH H 0 red EXAMPLE I43 N The dye of the formula: I  
  (H C N CN in 50 parts of pyridine, dripping in 2.8 parts of benzoyl chloride at C and stirring for 1 hour at this tempera 6s ture. After cooling to 20C the reaction solution is stirred into 500 parts of water, suction filtered, washed is obtained by dissolving 3.8 parts of the dye of the forwith 1000 parts of water and dried. The yield is 4.l mula: parts and the melting point is 270 to 272C.  
  EXAMPLE 144 N The dye of the formula: Q  
  I 5 (H 0 M92 Q CN fi (H C l N o is obtained as described in Example I46 by using 7.6 5 2 2 (3N parts of o-toluenesulfochloride instead of benzenesulfochloride. The yield is 4.4 parts and the melting point is obtained by repeating Example I43 but using 3.6 is 212 to parts of p-chlorobenzoyl chloride instead of benzoyl EXAMPLE 148 chloride. The yield is 4.2 parts and the melting point is [5 300 0 302 The dye of the formula:  
 EXAMPLE 145 The dye of the formula:  
 is obtained by repeating Example 146, using 7.6 parts of p-toluenesulfochloride and stirring for only 1 hour instead of 3 hours at refluxing temperature. The yield is 4.4 parts and the melting point is 220 to 225C.  
 EXAMPLE 149 The dye of the formula:  
 is obtained by repeating Example l43 but using 4.19 parts of 2,4-dichlorobenzoyl chloride instead of benzoyl chloride. The yield is 4.9 parts and the melting point is 270 to 273C.  
 EXAMPLE 146 The dye of the formula:  
 is obtained by dissolving 3.8 parts of the dye of the for- (H C N&#39; l mula. 5 2 2 CN in parts of o-dichlorobenzene, dripping 96 parts of phenyl isocyanate in at 100C and stirring for 1 hour at C. After cooling and suction filtration the yield is 4.2 parts and the melting point is 268 to 270C. (H c N o 55 5 2 2 CN EXAMPLE The dye of the formula: in 50 parts of pyridine, dripping 7.l parts of benzenesulfochloride in at 80C and stirring under reflux for 3 hours. After cooling to 20C the reaction solution is stirred into 500 parts of water, suction filtered, washed with 2000 parts of water and dried. The yield is 4.4 parts and the melting point is 220 to 222C.  
 EXAMPLE I47 The dye of the formula:  
 is obtained by dissolving 4.85 parts of the dye from Example 143 in 130 parts of o-dichlorobenzene, dripping 1.5l parts of dimethyl sulfate in and stirring for 3 hours at C. The whole is then cooled to 20C, parts a of petroleum ether (4060) is added and the product 5 (A) 1 m 11 IS suction filtered. The yield is 5.1 parts and the melting Z point is 228 to 230C. 2 11 1 The dyes characterized in the following Table by 5 their substituents are obtained by methods analogous Z to those described in the foregoing Examples:  
 Example 2. Z Z Z m n A X-Z Z Hue on polyester 151 C 11 C 11 H 1 O COCH CN red 152 H 1 0 c0c 11 CN r&#39;ed 153 H 1 o so cH on red I ll H 1 5 l H 1 O CO2C2H5 CN red 155 H 1 O CO2CI+H9 CN Yed 156 H 1 o CO C H CN red H II 157 H 2 O COQCQHACO2 CN red 158 H 2 O OCNH N&#39;HCO CN red 159 a 2 0 ocQ-co CN red 16o 11 2 0 co c 11 0c 11 c0 CN red 161 H 1 O OCNH CN red 162 H 1 o OC-CH -C-CH CN red ll 5 O 16} H l O 06-0 11 CN red 16 1 H 1 o OC-CH=CH on red 165 c 11 c 11 11 1 0 OCO-NO CN red 9 1 66 H 1 O C-NHC I-I9 CN red 9 1 67 H 1 0 C-CH= 011G CN red VI 168 c 11 c 11 1-1 1 0 43-1111 CN red 9 Cl 169 C2115 C2115 H 1 O -C-CH,; ,-OCIJ H9 CN red 9 170 c 11 0 11 H 1 o -c-o on red 9 C d 171 c 11 c 11 11 1 0 c NHQ N re OCH 172 C H C1 C H CI H 1 O COC H CN r&#39;ed Continued Example Z Z Z Z m n A )(-Z Z Hue on polyester We claim: Z is hydrogen, carbalkoxy having a total of two to 1. A dye of the formula five carbon atoms, carbo-B-methoxyethoxy, carbo- \A tg&#39; i Y z Z5 where Z is methyl, ethyl, benzyl, B-hydroxyethyl, B-hydroxypropyl, B-hydroxy-y-chloropropyl, B-cyanoethyl or B-carbalkoxyethyl, said alkoxy having one to four carbon atoms,  
 Z is alkyl of one to four carbon atoms, hydroxyalkyl of two to three carbon atoms, cyanoethyl, methoxyethyl, ethoxyethyl, methoxypropyl, acetoxyethyl, acetoxypropyl, carbalkoxyethyl, said alkoxy having one to four carbon atoms, benzyl or phenylethyl,  
 Z is hydrogen, alkyl of one to four carbon atoms or hydroxyethyl,  
 Z and Z together with the nitrogen are pyrrolidine,  
 piperidine, morpholine, piperazine or N-methylpiperazine,  
 Z is hydrogen, methyl, methoxy, chlorine, cyano or nitro, 4  
 m is 1 or 2,  
 n is 0 0r 1,  
 2 (when m l) is alkyl of one to four carbon atoms, chloromethyl, bromomethyl, alkoxymethyl, said alkoxy having one to four carbon atoms, B-chloroethyl, B-bromoethyl, cyclohexyl, B-phenylvinyl, alkoxy of one to four carbon atoms, B-methoxyethoxy, B-ethoxyethoxy, phenyl, phenyl substituted by chloro, nitro, methyl or methoxy, alkylamino of one to four carbon atoms, cyclohexylamino, benzylamino, phenylamino or phenylamino substituted by chloro, trifluoromethyl, methyl or methoxy, and (when m 2) is methylene, ethylene, phenylene, &#39;O-C2H40, 0CgH4OCH4O- 0r B-ethoxyethoxy, cyano, phenyl, phenylsulfonyl, carbamoyl, carbamoyl substituted at the nitrogen once or twice by alkyl of one to four carbon atoms, hydroxyalkyl of two to three carbon atoms, cyanoethyl, cyclohexyl, benzyl or phenyl, carbopyrrolidide, carbopiperidide, carbo-morpholide, carbo-piperazide or carbo-N-methylpiperazide,  
 Z is hydrogen or methyl and A&#34; is a chloride, bromide, nitrate, sulfate, methosulfate, ethosulfate, phosphate, thiocyanate, formate, acetate, tolylsulfonyl or tetrachlorozincate anion 2. A dye as claimed in claim 1 in which B is NX),,, Z.  
  3. A dye as claimed in claim 1 where B is oxygen or imino and Z is hydrogen, phenyl or phenylsulfonyl.  
 4. A dye as claimed in claim 1 where m l.  
  5. A dye as claimed in claim 1 where Z and Z are methyl or ethyl.  
 6. A dye as claimed in claim 1 where n 0.  
 7. A dye as claimed in claim 1 where n is 0,  
 m is l,  
 Z and Z are methyl or ethyl,  
 Z is hydrogen, chloro or methyl,  
 Z is hydrogen or methyl,  
 Z and Z have the meanings given in claim 1.  
  8. A dye as claimed in claim 7, where Z is phenyl or phenyl substituted by chloro, nitro, methyl or methoxy and Z has the meaning given in claim I.  
  9. A dye as claimed in claim 8 where Z is hydrogen, cyano, carbalkoxy having a total of two to five carbon atoms, carbo-B-methoxyethoxy, carbo-B- ethoxyethoxy, carbamoyl, carbamoyl substituted at the nitrogen once to twice by alkyl of one to four carbon atoms, hydroxyalkyl of two or three carbon atoms, cyanoethyl, cyclohexyl, benzyl or phenyl, carbopyrrolidide, carbo-piperidide, carbo-morpholide, carbo-piperazide or carbo-N-methylpiperazide.