WO2012001708A1

WO2012001708A1 - Process for preparing of dioxazine pigments

Info

Publication number: WO2012001708A1
Application number: PCT/IN2011/000433
Authority: WO
Inventors: Gharda Keki Hormusji; Taher S. Dakorwala
Original assignee: Gharda Keki Hormusji
Priority date: 2010-06-30
Filing date: 2011-06-29
Publication date: 2012-01-05
Also published as: WO2012001708A8

Abstract

Disclosed is a process for preparing dioxazine pigments of formula I, preferably Pigment Violet 23(wherein R=C₂H₅), from compounds of formula II. The compounds of formula II are cyclized to form the dioxazine compounds of formula I in organic solvent b using a cyclizing agent such as air and/or oxygen. (Formula II, I)

Description

PROCESS FOR PREPARING DIOXAZINE PIGMENTS

Field of the invention

The present invention relates to a process for preparing Dioxazine pigments. The present invention envisages a process for preparing Pigment Violet 23.

BACKGROUND OF THE INVENTION

Dioxazine compounds are used in the synthesis of valuable dyes and pigments. Dioxazine compounds are industrially prepared in a five-stage synthesis involving N-alkylation of carbazole, followed by nitration, reduction, condensation and ring closure as disclosed in patents US4345074, US5932727, JP58118855, WO2002/053654 and US6359131.

Pigment violet 23, belonging to Dioxazine class of pigments has been known for decades and has acquired a very great importance because of its outstanding properties as a colorant.

C.I. Pigment Violet 23 [CI 51319, "Carbazole Violet"] is an important commercial pigment and is available in many grades, for example as Cromophtal(R) Violet GT (Ciba Spezialitaten-chemie AG), Hostaperm(R) Violet RL Special (Clariant) or Fastogen(R) Super Violet RN (Dainippon Ink). Gafast PV23.

Pigment Violet 23 is widely used colorant and is manufactured on an industrial scale in large quantities. It is typically synthesized by cyclization of 2,5-di-(9- ethylcarbazol -3-ylamino)-3,6-dichloro-l, 4-benzoquinone (Ref: Venkataraman, The Chemistry of Synthetic Dyes, Volume II (1952), pages 786 and 787).

DE-A 3010949 discloses cyclization process of 2,5-di-(9-ethylcarbazol -3- ylamino)-3,6-dichloro-l, 4-benzoquinone, using ring closure agents, such as benzenesulfonyl chloride, 4-toluenesulfonyl chloride, nitro- or chloro-substituted benzenesulfonyl chloride, chloranil, chlorine and pyridine N-oxide Cyclization is carried out at high temperatures .

German Patent Specification No. 517194 discloses use of cyclizing agents such as metal chlorides or benzenesulphochloride (Venkataraman Loc.ci , Volume 2 (1952), page 787) in presence of inert solvents having boiling point greater than 160°C.

When aryl sulfonyl chlorides including other isomers of toluenesulfonyl chlorides, naphthalenesulfonyl chlorides, anthracenesulfonyl chlorides or other aryl systems are employed as the cyclization agents, the following by-products (1), (2), and (3) are formed.

( 3 ) The amount of these by-products retained in the isolated crude product is removed by further process of purification. Rigorous washing of the crude product with the hot solvent removes virtually all of the by-product compounds. However, this results in high residue in the filtrate during solvent recovery and poses major pollution problems. Approximately 1 kg of residue is generated per kg of dioxazine pigment.

It is therefore felt a need to develop a suitable process for cyclizing benzoquinone derivatives to dioxazine pigments.

OBJECT OF THE INVENTION.

Main object of the present invention is to provide a feasible process for preparing dioxazine pigments.

Another object of the present invention is to provide a process for dioxazine pigments, which avoids the use of hazardous cyclisation agents.

Yet another object of the present invention is to provide a process for preparing dioxazine pigments, which avoids the formation of by-products.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a process for preparing dioxazine pigments of formula I,

Formula I wherein R is selected from the group consisting of hydrogen, straight-chain Ci-C₈ alkyl branched C_t-C₈ alkyl. said process comprising the following steps of; a) condensing chloranil with aminocarbazole derivative of formula III to yield a compound of formula II ; and

Formula II

Formula III

wherein R is selected from the group consisting of hydrogen, straight-chain Ci-C₈ alkyl and branched C I -C8 alkyl. b) cyclizing the compound of formula II in situ, using a cyclizing agent selected from the group consisting of air and oxygen, to yield a dioxazine pigment of formula I. In a preferred embodiment of the present invention, the process is carried out in the presence of a metal salt catalyst.

Typically, the metal salt catalyst is at least one selected from the group consisting of metallic compounds of Mn, Co, Fe, Cu and Ni.

Typically, the metal salt catalyst is at least one selected from the group consisting of Manganese acetate, manganese chloride, cobalt chloride and cobalt acetate.

In a preferred embodiment of the present invention, the amount of the metal salt catalyst used is in the range of up to 0.25% by weight of aminocarbazole derivative of formula III.

Typically, the step of cyclization is carried at a pressure range of 1 kg/cm2 to 10 kg/cm2 pressure.

Typically, the step of cyclization is carried at a temperature range from 140°C to 200°C.

Typically, the process is carried out in an inert organic solvent. The inert organic solvent is selected from the group consisting of ortho-dichloro benzene, nitrobenzene, quinoline, alkanes, alkenes and halogenated monoalkyl-, dialkyl- trialkylbenzenes, and alkylnaphthalenes.

Typically, the inert organic solvent is ortho-dichloro benzene.

In a preferred embodiment of the present invention, R is an ethyl group.

In a preferred embodiment of the present invention, the compound of formula I is pigment violet 23. Detailed Description of the present invention

C.I. Pigment Violet 23 [CI 51319, "Carbazole Violet"] of formula I as represented below, wherein R is ethyl group is an important commercial pigment and is available in many grades, for example as Cromophtal(R) Violet GT (Ciba Spezialitaten-chemie AG), Hostaperm(R) Violet RL Special (Clariant) or Fastogen(R) Super Violet RN (Dainippon Ink). Gafast PV23.

During the cyclization study involving the preparation of dioxazine compounds it has been found that air (enriched with oxygen) or oxygen can be used as ring closure agents for the synthesis of the dioxazine compounds from Compound of Formula II.

Formula !l Dioxazine Pigment

Wherein, R is hydrogen or straight-chain or branched Ci-C₈ alkyl

The present invention accordingly provides a process for preparing dioxazines by ring closure of a compound of the formula (II), wherein R is hydrogen or straight- chain or branched Cj-Cs alkyl, in presence of oxygen. The cyclization can also be carried in presence of air (enriched with 19-20% of oxygen). The cyclization is carried out in inert organic solvent. Further, the process is carried out in presence of a metal salt catalyst.

The metal salts are preferably chlorides and acetates of transition metals such as Mn, Co, Fe, Cu and Ni.

Metal salt catalyst is found to improve the reaction rate of the process and also enhances the quality of the pigments formed. It is observed that the cyclization does not proceed to completion in the absence of metal catalyst.

It is also observed that the dioxazine compounds formed in the process of the present invention are free from the impurities of the formula (1), (2) or (3).

In accordance with the present invention, chloranil is condensed with an aminocarbazole derivative of formula III as represented below to yield a compound of formula II. Cyclization of compound of formula II is carried out in-situ using air or oxygen as cyclizing agents. Air (enriched with 19-20% oxygen) or oxygen is bubbled into the reaction mixture containing a compound of formula II, an inert solvent and a transition metal catalyst, at a pressure range of 1 to 10 kg/cm2 pressure.

R

Formula II I The amount of catalyst used is up to 0.25wt% of the aminocarbazole derivative. The reaction temperature is maintained within the range from 140°C to 200°C, preferably from 160 to 170°C. The reaction generally takes 1 to 10 hours for complete cyclization. After completion of reaction, the reacted mixture is filtered at 80°C to 150°C. The residual cake is washed with the inert solvent and dried to yield dioxazine pigment free of impurities. Solvent traces from the pigment can be removed completely by means of steam distillation or drying. In order to remove the water-soluble byproducts, the product is generally suspended in water, washed and dried.

The following equation illustrates the synthetic reaction scheme of the present invention.

Acid acceptor

- 2 HCI

Chloranil

Dioxazine Compound

Formula

Formula I

Wherein, R is hydrogen or straight-chain or branched Q-Cs alkyl In a preferred embodiment of the present invention, Compound of formula II i.e. 2, 5-di-(9-ethylcarbazol-3-ylamino)-3,6-dichloro-l,4-benzoquinone is synthesized by condensing chloranil and 3-amino-N-ethylcarbazole in presence of sodium acetate. 2,5-di-(9-ethylcarbazol-3-ylamino)-3,6-dichloro-l,4-benzoquinone so formed is then further cyclized in-situ in accordance with the process as described above to prepare dioxazine compound Pigment Violet 23.

The present invention provides an environmentally friendly process which yields a dioxazine compound, free of impurities. The dioxazine compound is easily converted to finished pigmentary form by use of processes known in art or by a simple, environmental and economical friendly process by use of alkyl / aryl sulfonic acid as solvent.

The invention will now be described with respect to the following examples which do not limit the invention in any way and only exemplify the invention

EXAMPLES

Example 1

147 gm of 3-amino-N-ethylcarbazole in 1 lit of orthodichlorobenzene (ODCB) was charged in a reactor. The mixture was heated to 45°C and 122 gm chloranil and 105 gm of sodium acetate trihydrate were simultaneously added to the mixture over a period of 4 hrs. The resultant mixture was further heated to 105 °C and the acetic acid generated was removed by distillation. The mixture was then further heated to 170 °C, 0.30 gm of Cobalt acetate was added and the reactor was pressurized with the oxygen at lkg/cm2 for a period of 6 hrs till the completion of reaction as monitored by TLC. The reacted mixture was then cooled to 80 °C and filtered. The filter cake was washed with 250 ml of hot ODCB, and dried in vacuum at 100°C. The product was further purified by washing it with water, filtering and drying in an oven. The final yield of the product is 180 g of the dioxazine compound (87.3% of theory). The high purity of the product is evident from the elemental analysis, IR absorption spectrum, mass spectrum, X-ray diffractogram, and from the performance properties. The ODCB filtrate was recovered by distillation (distillation residue was 306 gm per kg of dioxazine pigment obtained).

Example 2

147 gm of 3-amino-N-ethylcarbazole in 1 lit of orthodichlorobenzene (ODCB) was charged in a reactor. The mixture was heated to 45°C and 122 gm chloranil and 105 gm of sodium acetate trihydrate were simultaneously added to the mixture over a period of 4 hrs. The resultant mixture was further heated to 105 °C and the acetic acid generated was removed by distillation. The mixture was then heated to 160°C and 68 gm of benzenesulfonychloride was added over a period of 30 minutes. The reaction mixture was cooled to 150° C and filtered. The filter cake was washed with 250 ml hot ODCB (three times), and dried in vacuum at 100°C. The product was further purified by treating it with water. The final yield was 175 g of the dioxazine compound (85% of theory). The ODCB filtrate was recovered by distillation (distillation residue obtained was 800 gm per kg of dioxazine pigment obtained). Example 3

147 gm of 3-amino-N-ethylcarbazole in 1 lit of orthodichlorobenzene (ODCB) was charged in a reactor. The mixture was heated to 45 °C and 122 gm chloranil and 105 gm of sodium acetate trihydrate were simultaneously added to the mixture over a period of 4 hrs. The resultant mixture was further heated to 105 °C and the acetic acid generated was removed by distillation. The mixture was then further heated to 170°C and 0.15 gm of Cobalt chloride was added to the mixture .Oxygen was passed into the mixture for a period of 6 hrs at atmospheric pressure till completion of reaction as monitored by TLC. The reaction mixture was cooled to 80°C and filtered. The filter cake was washed with 250 ml of hot ODCB, and dried in vacuum at 100 °C. The product was further purified. The yield was 175 g of the dioxazine compound (85% of theory). The high purity of the product is evident from the elemental analysis, IR absorption spectrum, mass spectrum, X-ray diffractogram, and from the performance properties. The ODCB filtrate was recovered by distillation (distillation residue was 350 gm per kg of dioxazine pigment obtained).

Example 4

147 gm of 3-amino-N-ethylcarbazole in 1 lit of orthodichlorobenzene (ODCB) was charged in a reactor. The mixture was heated to 45 °C and 122 gm chloranil and 105 gm of sodium acetate trihydrate were simultaneously added to the mixture over a period of 4 hrs. The resultant mixture was further heated to 105 °C and the acetic acid generated was removed by distillation. The mixture was then further heated to 170°C and 0.1 gm of Cobalt acetate was added to the mixture .Oxygen was passed into the mixture for a period of 6 hrs at atmospheric pressure till completion of reaction as monitored by TLC. The reaction mixture was cooled to 80°C and filtered. The filter cake was washed with 250 ml of hot ODCB, and dried in vacuum at 100 °C. The product was further purified. The yield was 173 g of the dioxazine compound (84% of theory). The high purity of the product is evident from the elemental analysis, IR absorption spectrum, mass spectrum, X-ray diffractogram, and from the performance properties. The ODCB filtrate was recovered by distillation (distillation residue was 350 gm per kg of dioxazine pigment obtained).

Example 5

147 gm of 3-amino-N-ethylcarbazole in 1 lit of orthodichlorobenzene (ODCB) was charged in a reactor. The mixture was heated to 45 °C and 122 gm chloranil and 105 gm of sodium acetate trihydrate were simultaneously added to the mixture over a period of 4 hrs. The resultant mixture was further heated to 105 °C and the acetic acid generated was removed by distillation. The mixture was then further heated to 170°C and a 0.35 gm catalyst mixture (containing equal quantities of Cobalt chloride and Manganese chloride) was added to the reacted mixture. Air was passed into the mixture for a period of 6 hrs at atmospheric pressure (lkg/cm2) till completion of reaction as monitored by TLC. The reaction mixture was cooled to 80°C and filtered. The filter cake was washed with 250 ml of hot ODCB, and dried in vacuum at 100 °C. The product was further purified. The yield was 185 g of the dioxazine compound (90% of theory). The high purity of the product is evident from the elemental analysis, IR absorption spectrum, mass spectrum, X-ray diffractogram, and from the performance properties. Example 6

147 gm of 3-amino-N-ethylcarbazole in 1 lit of orthodichlorobenzene (ODCB) was charged in a reactor. The mixture was heated to 45°C and 122 gm chloranil and 105 gm of sodium acetate trihydrate were simultaneously added to the mixture over a period of 4 hrs. The resultant mixture was further heated to 105 °C and the acetic acid generated was removed by distillation. The mixture was then further heated to 170°C and a catalyst of 0.35 gm of Cobalt acetate was added to the mixture. Air was passed into the mixture for a period of 6 hrs at atmospheric pressure till completion of reaction as monitored by TLC. The reaction mixture was cooled to 80°C and filtered. The filter cake was washed with 250 ml of hot ODCB, and dried in vacuum at 100 °C. The product was further purified. The yield was 185 g of the dioxazine compound (90% of theory). The high purity of the product is evident from the elemental analysis, IR absorption spectrum, mass spectrum, X-ray diffractogram, and from the performance properties.

Example 7

147 gm of 3-amino-N-ethylcarbazole in 1 lit of orthodichlorobenzene (ODCB) was charged in a reactor. The mixture was heated to 45°C and 122 gm chloranil and 105 gm of sodium acetate trihydrate were simultaneously added to the mixture over a period of 4 hrs. The resultant mixture was further heated to 105 °C and the acetic acid generated was removed by distillation. The mixture was then further heated to 170°C and a catalyst mixture containing 0.15 gm of Cobalt chloride and 0.15 gm of Manganese chloride was added to the reacted mixture .Oxygen was passed into the mixture for a period of 6 hrs at atmospheric pressure till completion of reaction as monitored by TLC. The reaction mixture was cooled to 80°C and filtered. The filter cake was washed with 250 ml of hot ODCB, and dried in vacuum at 100 °C. The product was further purified. The yield was 181 g of the dioxazine compound (88% of theory). The high purity of the product is evident from the elemental analysis, IR absorption spectrum, mass spectrum, X-ray diffractogram, and from the performance properties.

Example 8

147 gm of 3-amino-N-ethylcarbazole in 1 lit of orthodichlorobenzene (ODCB) was charged in a reactor. The mixture was heated to 45°C and 122 gm chloranil and 105 gm of sodium acetate trihydrate were simultaneously added to the mixture over a period of 4 hrs. The resultant mixture was further heated to 105 °C and the acetic acid generated was removed by distillation. The mixture was then further heated to 170°C and 0.25 gm of Cobalt acetate was added to the mixture .Oxygen was passed into the mixture for a period of 3 hrs at 10 kg/cm2, till completion of reaction as monitored by TLC. The reaction mixture was cooled to 80°C and filtered. The filter cake was washed with 250 ml of hot ODCB, and dried in vacuum at 100 °C. The product was further purified. The yield was 175 g of the dioxazine compound (85% of theory). The high purity of the product is evident from the elemental analysis, IR absorption spectrum, mass spectrum, X-ray diffractogram, and from the performance properties. The ODCB filtrate was recovered by distillation (distillation residue was 320 gm per kg of dioxazine pigment obtained).

Example 9 147 gm of 3-amino-N-ethylcarbazole in 1 lit of nitrobenzene was charged in a reactor. The mixture was heated to 45 °C and 122 gm chloranil and 105 gm of sodium acetate trihydrate were simultaneously added to the mixture over a period of 4 hrs. The resultant mixture was further heated to 105 °C and the acetic acid generated was removed by distillation. The mixture was then further heated to 170°C and 0.35 gm of catalyst mixture (containing equal quantities of Cobalt chloride and Manganese chloride) was added to the reacted mixture .Oxygen was passed into the mixture for a period of 4 hrs at 6 Kg/cm2, till completion of reaction as monitored by TLC. The reaction mixture was cooled to 80°C and filtered. The filter cake was washed with 250 ml of hot nitrobenzene, and dried in vacuum at 100 °C. The product was further purified. The yield was 168 g of the dioxazine compound (82% of theory). The high purity of the product is evident from the elemental analysis, IR absorption spectrum, mass spectrum, X-ray diffractogram, and from the performance properties. The nitrobenzene filtrate was recovered by distillation (distillation residue was 350 gm per kg of dioxazine pigment obtained).

Technical Advancement

It is observed that using benzene sulfonic acid as a cyclisation agent, the residue at the end of crude PV 23 obtained was 700 gm/kg i.e 412.3 gm/m of PV 23, and in case of present invention utilizing air/oxygen as a cyclizing agents, the residue was 306 gm/kg (180.36 gm/m). Thus the object of the invention to reduce the formation of byproducts during formation of dioxazine compounds of formula (I) is achieved by this process.

While considerable emphasis has been placed herein on the specific steps of the preferred process, it will be appreciated that additional steps can be made and that many changes can be made in the preferred steps without departing from the principles of the invention. These and other changes in the preferred steps of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Claims

Claims:

1. A process for preparing dioxazine pigments of formula I,

Formula I wherein R is selected from the group consisting of hydrogen, straight-chain Ci-C₈ alkyl and branched Cj-C₈ alkyl. said process comprising the following steps of; a) condensing chloranil with aminocarbazole derivative of formula III to yield a compound of formula II ; and

R Formula II

Formula III

wherein R is selected from the group consisting of hydrogen, straight-chain Q-Cg alkyl and branched Ci-Cg alkyl. b) cyclizing the compound of formula II in situ, using a cyclizing agent selected from the group consisting of air and oxygen, to yield a dioxazine pigment of formula I.

2. The process as claimed in claim 1, wherein the process is carried out in the presence of a metal salt catalyst.

3. The process as claimed in claim 1, wherein the metal salt catalyst is at least one selected from the group consisting of metallic compounds of Mn, Co, Fe, Cu and Ni.

4. The process as claimed in claim 1 , wherein the metal salt catalyst is at least one selected from the group consisting of Manganese acetate, manganese chloride, cobalt chloride and cobalt acetate.

5. The process as claimed in claim 1, wherein the amount of the metal salt catalyst used is in the range of up to 0.25% by weight of aminocarbazole derivative of formula III.

6. The process as claimed in claim 1, wherein the step of cyclization is carried at a pressure range of 1 kg/cm² to 10 kg/cm² pressure.

7. The process as claimed in claim 1, wherein the step of cyclization is carried at a temperature range from 140°C to 200°C.

8. The process as claimed in claim 1, wherein the process is carried out in an inert organic solvent.

9. The process as claimed in claim 1 , wherein the inert organic solvent is selected from the group consisting of ortho-dichloro benzene, nitrobenzene, quinoline, alkanes , alkenes, halogenated-monoalkyl, dialkyl, tnalkylbenzenes and alkyl naphthalenes.

10. The process as claimed in claim 1, wherein an inert organic solvent is ortho- dichloro benzene.

11. The process as claimed in claim 1, wherein R is ethyl group

12. The process as claimed in claim 1, wherein the dioxazine compound of formula I is pigment violet 23.