GB2075540A - Cationic Dyestuffs - Google Patents

Abstract

Novel cationic dyes of the diazahemicyanine class for polyacrylonitrile are derived from a pyrrocoline (indolizine) coupling component. The dyes have the formula (I): <IMAGE> wherein D is a 5 or 6 membered heterocyclic ring containing a ring nitrogen atom and either one or more further ring hetero atoms or a fused aromatic system or both, R, which is attached to the ring nitrogen atom in D, is optionally substituted lower alkyl, alkenyl, cycloalkyl or aralkyl, R<1> and R<2>, which are the same or different, are optionally substituted alkyl, aryl or aralkyl, or R<2> is hydrogen, ring B is optionally substituted, and A<(-)> is an anion.

Description

SPECIFICATION Cationic Dyestuffs This invention relates to water soluble azo dyestuffs useful for the colouration of synthetic polymeric material particularly polymers and copolymers of acrylonitrile and dicyanoethylene and also acid modified polyesters and polyamides.

According to the present invention there are provided water soluble azo dyestuffs devoid of carboxylic acid and sulphonic acid groups of formula (I):

wherein D is a 5 or 6 membered heterocyclic ring containing a ring nitrogen atom and either one or more further ring hetero atoms or a fused aromatic system or both, R, which is attached to the ring nitrogen atom in D, is optionally substituted lower alkyl, alkenyl, cycloalkyl or aralkyl, R' and R2, which are the same or different, are optionally substituted alkyl, aryl or aralkyl, or R2 is hydrogen, ring B is optionally substituted, and Ao is an anion.

The term "lower" when applied herein to an alkyl or alkyl containing group refers to such a group where each alkyl part contains from 1 to 4 carbon atoms.

The ring B may be substituted with one or more of the substituents normally to be found in dyestuff molecules.

In referring to the pyrrocoline (also called indolizine) nucleus (II) we use the following numbering:

The azo moiety in the dyestuffs of the invention may be attached to the pyrrocoline nucleus at the 1- or 3-position, R2 being attached to the position unoccupied by the azo moiety.

Preferably, however, the azo moiety is attached to the 3-position of the pyrrocoline nucleus as we have found that in this position the dyestuffs exhibit better light fastness.

More particularly we would mention the dyestuffs of formula (III):

wherein D1 is thiazolyl, isothiazolyl, benzthiazolyl, 2,1 -benzisothiazolyl, 1 2,4-triazolyl, pyridyl, quinolyl, benzimidazolyl, pyrazolyl, 1,2,4-thiadiazolyl, 1,3,4-thiadiazolyl, indazolyl or imidazolyl, R3, which is attached to a ring nitrogen atom in D, is optionally substituted lower alkyl, R4 and R5, which are the same or different, are methyl or phenyl, or R5 is hydrogen, and As has the meaning hereinbefore defined.

Of especial interest are the dyestuffs of formula (IV):

wherein R6 is methyl or phenyl, R7 is hydrogen or methyl and Ao has the meaning hereinbefore defined.

The anion A may be any organic- or inorganic-based anion known to be used with cationic dyestuffs such as those described in UK Patent Specification No. 1,508,500. In particular we would mention chloride, methyl sulphate, acetate, bisulphate and tetrachlorozincate. Where A is polyvalent the dyestuff will contain a corresponding molar proportion of the cationic moiety.

The dyestuffs are prepared by reacting a compound of formula (V):

with a quaternising agent of the formula RX, wherein D, B, R, R1 and R2 have the meanings hereinbefore defined and X is capable of providing an anionic moiety which is Ao, as hereinbefore defined, or an anionic moiety which can be exchanged for Ao by known methods of metathesis.

Suitable quaternising agents include those alkylating agents and other quaternising agents well known in the art and described in, for example, UK Patent Specification No. 1,508,580. Suitable known methods by which quaternisation can be carried out are also described in that specification.

The compound of formula (V) is prepared either by coupling a diazotised amine D-NH2 with a pyrrocoline compound of the formula (VI):

or in cases where the heterocyclic amine does not readily diazotise, by forming the corresponding hydrazine derivative and oxidatively coupling this to the pyrrocoline. D, B, R1 and R2 have the meanings herein before defined.

The pyrrocoline coupling components are conveniently obtained using a Tschitschibabin synthesis as described in 'The Chemistry of Heterocyclic Compounds", Volume 15 - 'Systems with Bridgehead Nitrogen' - Part One, Ed. Weissberger, Interscience Publishers Inc., N.Y., 1961, page 239.

In this synthesis a 2-alkyl or aralkyl pyridine (VII) is reacted with an cg-halogenoketone (VIII) to give a quaternary salt (IX). Treatment of this quaternary salt with a base (usually sodium bicarbonate) in water gives a pyrrocoline (X).

Hal. denotes halogen, which may be chlorine, bromine or iodine, but is most suitably bromine.

Since many lower alkyl pyrrocolines are unstable, the relatively stable quaternary salts (IX) are preferably stored and converted to the corresponding pyrrocoline immediately prior to coupling. This is simply done by warming the quaternary salt in aqueous sodium bicarbonate solution.

The dyestuffs of the present invention may be used to colour polymeric materials by conventional applications such as those described in UK Patent Specification No. 1 ,508,500.

In particular they are valuable for dyeing polyacrylonitrile materials giving bright orange to turquoise shades. In general they have good fastness properties and are particularly stable to hydrolysis and to steam pleating and dry heat.

The invention is illustrated but not limited by the following examples in which all parts and percentages are by weight unless otherwise stated. Where parts by volume are given, the relation to weight to volume is the relation of gram to millilitre.

Example 1 Diazotisation 1.5 parts of 3-amino-2,1 -benzisothiazole (prepared as described in Example 1, pages 5 and 6 of UK Patent Specification No. 1134579) is dissolved in a mixture of 25 parts by volume of phosphoric acid and 25 parts by volume of glacial acetic acid. After stirring and cooling to between 0 and 5"C, 0.7 parts of powdered sodium nitrite is added to the mixture by sprinkling and the reaction mixture stirred for one hour at O to 50C. Sufficient urea is then added to destroy the excess nitrous acid.

Coupling 1.44 parts of 2-methylindolizine, prepared as described below, is dissolved in 100 parts by volume of acetone and the solution stirred and cooled to between 0 and 50C. The diazo solution is run in and the resulting violet solution stirred for one hour at between 0 and 50C. The solution is added to 250 parts of water and the precipitate filtered off and washed with water.

The dye base is dissolved in acetone and the solution filtered to remove traces of insoluble material. The filtrate is added to 250 parts of water and the precipitated product filtered, washed with water and dried at 400C.

Preparation of 2-Methylindolizine The 2-methylindolizine used in this experiment was obtained by the method described by Holland and Naylor in The Journal of the Chemical Society, 1955, page 1660. Briefly it is as follows.

40 parts of 2-methyl pyridine is stirred in 50 ml of acetone at 250C and 56 parts of bromo acetone is added dropwise. The reaction mixture is refluxed for 12 hours when a precipitate of an offwhite solid is obtained. On cooling to 250C, further precipitation occurs. The product, which has the structure (IX) in which R8 and R9 are both hydrogen, R10 is methyl and hal. is bromine, is filtered off, washed copiously with acetone and dried at 4O0C.

23 parts of the quaternary bromide salt is dissolved'in 300 parts of water containing 20 parts of dissolved sodium bicarbonate and the solution boiled under reflux for 1 T hours. The 2-methyl indolozine is obtained from the reaction mixture by steam distillation. The distillate is then treated with diethyl ether, the ether extracts dried over anhydrous magnesium sulphate and the ether evaporated off to give as a pale yellow solid, 2-methyl indolizine which has the structure (X) in which R6 and R9 are both hydrogen and R10 is methyl.

Quaternisation 1.5 parts of the dye base is dissolved in 50 ml of chloroform and 0.4 parts of light magnesium oxide and 1.4 parts of dimethyl sulphate are added. The mixture is boiled under reflux for about half an hour until reaction is complete as judged using thin layer chromatography.

The chloroform is removed by evaporation, the residue dissolved in water and the solution filtered through hyflo supercel. The filtrate is extracted with 2 lots of 100 parts by volume of chloroform to remove the last traces of unquaternised material, and a dark green impurity.

Sodium chloride is added to the aqueous solution followed by zinc chloride, when a blue precipitate is formed. After filtering and washing with dilute brine, the product is dried at 400C. It has the formula:

and dyes "Orlon" (Registered Trade Mark) polyacrylonitrile material a bright turquoise shade, very similar to Basic Blue 3, C.l. 51004). It has good fastness properties, especially to steam pleating, dry heat setting and good stability to hydrolysis in the dyebath.

Examples 2-17 The dyestuffs tabulated below can be obtained by similar methods to that described in Example 1. The symbols Me, Et and Ph used in the Table denote methyl, ethyl and phenyl respectively.

Shade on I L, Dgestufi Mon PolJacrylo nitrile 20 He He 3i'C14 Ocange 4. Nei I.

Ph N.

y 5 Me jznc142 rquoise al Ne Ne I 6 Me =N I greea L UX

Shade on Shade on E Dgestuff Anion Polyacrylo nit rile 17 He 3zam, 2 4 GsN II N=N-a W Ne 0/memo He Ne |Ne a + Cl 2 Rtibine 4 9 Hee 'HoNe Violet fe Me sto C 2 Reddieh 10 ThN%N=N A' Cl violet NeO 11 Ne ON He . SI --NN 1 QN / He 12 , < > Me iZnC14 fr,N=N , Ne U 13 Ne He 32 Orange I) Ne

Shade on Dyestuff Anion Polyacrylo nitrile 14 0 Me He ZnCl42 Scarlet SIM > N=N t hue 15 Ne Ne I Orange t e 16 Ne 3zncl, fled I 4 N=N 17 < .. ..

A5%'N=N 'I Ne

Claims (10)

Claims

1. Water soluble azo dyestuffs devoid of carboxylic acid and sulphonic acid groups of formula (I):

wherein D is a 5 or 6 membered heterocyclic ring containing a ring nitrogen atom and either one or more further ring hetero atoms or a fused aromatic system or both, R, which is attached to the ring nitrogen atom in D, is optionally substituted lower alkyl, alkenyl, cycloalkyl, or aralkyl, R1 and R2, which are the same or different, are optionally substituted alkyl, aryl or aralkyl, or R2 is hydrogen, ring B is optionally substituted, and AO is an anion.

2. Azo dyestuffs according to claim 1 in which the azo moiety is attached to the 3-position of the pyrrocoline nucleus.

3. Azo dyestuffs according to claim 2 having the formula (III):

wherein D1 is thiazolyl, isothiazolyl, benzthiazolyl, 2,1 -benzisothiazolyl, 1 2,4-triazolyl, pyridyl, quinolyl, benzimidazolyl, pyrazolyl, 1 ,2,4-thiadiazolyl, 1 ,3,4-thiadiazolyl, indazolyl or imidazolyl, R3 which is attached to a ring nitrogen atom in D, is optionally substituted lower alkyl, R4 and R5, which are the same or different, are methyl or phenyl, or R5 is hydrogen, and Ao has the meaning given in claim 1.

4. Azo dyestuffs according to claim 3 having the formula (VI):

wherein R6 is methyl or phenyl, R7 is hydrogen or methyl and AS has the meaning given in claim 1.

5. Azo dyestuffs substantially as described herein with reference to any one of Examples 1 to 1 7.

6. Process for the manufacture of azo dyes according to claim 1, which comprises reacting a compound of formula (V):

with a quaternising agent of the formula RX, X being capable of providing an anionic moiety which is Ae, having the meaning given in claim 1, or an anionic moiety which can be exchanged for AO by known methods of metathesis.

7. Process for the manufacture of azo dyes according to claim 1 substantially as herein described with reference to any one of Examples 1 to 17.

8. Process for colouring a polymeric material which comprises treating the material with a dyestuff according to any one of claims 1 to 5.

9. Process according to claim 8 in which the polymeric material is polyacrylonitrile.

10. Polymeric material coloured by a process according to claims 8 or 9.