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GB2084604A - Process for the preparation of malachite green oxalate - Google Patents

Process for the preparation of malachite green oxalate Download PDF

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Publication number
GB2084604A
GB2084604A GB8128953A GB8128953A GB2084604A GB 2084604 A GB2084604 A GB 2084604A GB 8128953 A GB8128953 A GB 8128953A GB 8128953 A GB8128953 A GB 8128953A GB 2084604 A GB2084604 A GB 2084604A
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United Kingdom
Prior art keywords
malachite green
oxalic acid
dyestuff
process according
reaction
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Application number
GB8128953A
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GB2084604B (en
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Bayer AG
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Bayer AG
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Publication date
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Publication of GB2084604B publication Critical patent/GB2084604B/en
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    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09BORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
    • C09B11/00Diaryl- or thriarylmethane dyes
    • C09B11/04Diaryl- or thriarylmethane dyes derived from triarylmethanes, i.e. central C-atom is substituted by amino, cyano, alkyl
    • C09B11/10Amino derivatives of triarylmethanes
    • C09B11/12Amino derivatives of triarylmethanes without any OH group bound to an aryl nucleus
    • C09B11/20Preparation from other triarylmethane derivatives, e.g. by substitution, by replacement of substituents

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

Malachite green oxalate is prepared by reacting malachite green dyestuff base and oxalic acid in the melt.

Description

SPECIFICATION Process for the preparation of malachite green oxalate The present invention relates to a process for the preparation of malachite green oxalate by reacting the dyestuff base of malachite green with oxalic acid in the melt.
The dyestuff base and oxalic acid are preferably reacted in a molar ratio of 1:1.4-2.5, in particular 1:1.4-1.6, in the presence of at least 30100% by weight, and in particular 30-40% by weight (relative to the melt), of water. The water content datum relates to the total water present in the reaction mixture, that is to say that it also includes the water liberated during the neutralisation.
The reaction temperature is preferably 40--700C, in particular 40--600C. A reaction temperature of 45-500C is to be especially mentioned.
The oxalic acid is preferably used in the form of crystals having the composition C2H2 04. 2H2 0.
In the process according to the invention, the water content and reaction temperature are adjusted such that a melt which is capable of flowing and can be stirred is formed at this temperature.
The malachite green oxalate is dried at a maximum temperature of 750C, preferably at 45-500C, in vacuo.
The process can be carried out industrially by a procedure such that the reaction and drying take place in the same reaction equipment (for example a vacuum paddle drier). However, it is also possible to carry out the reaction in a stirred container and to dry the resin under the given conditions by any desired industrial drying process.
The known process, which can be used industrially, for the preparation of malachite green (Colour Index 42 000) comprises subjecting benzaldehyde to a condensation reaction with dimethylaniline, oxidising the leuco-base with lead dioxide, isolating the dyestuff as the Pb salt converting the lead salt into the dyestuff base, isolating the dyestuff base, dissolving the base in aqueous oxalic acid and crystallising out the oxalate. This process is described, for example, in Ullmanns Encyclopadie der techn. Chemie (Ullmanns Encyclopaedia of Industrial Chemistry), Volume 17 (1966), pages 666-667.
The disadvantage of the process carried out on this basis is the large amount of water required for dissolving the dyestuff. To prepare an aqueous solution of malachite green oxalate which is saturated at 700 C, about four times the amount by weight of water is required. The mother liquor obtained after the crystallisation during isolation of the dyestuff pollutes the effluent and gives rise to a loss in yield.
Surprisingly, it has now been found that a dyestuff of which the physical and coloristic properties are identical to the properties of the dyestuff which can be obtained by the known process is obtained by the new process, in which these disadvantages are avoided. In particular, it could not be predicted that the composition of the crystals of the dyestuffs prepared by the two processes would be stoichiometrically identical.
Example 100 kg of moist malachite green dyestuff base (water content: 28.2%) are introduced into a container, which is warmed to 45 to 500C, whilst stirring, and 25 kg of crystalline oxalic acid (C2H204.2H2O) are added in the course of 5 minutes. After at most 10 minutes, the batch is mobile and homogeneous. A total of 1,600 kg of the dyestuff base and 400 kg of the crystalline oxalic acid are now added in portions. A further 223 kg of crystalline oxalic acid are then introduced into the mobile homogeneous mixture.
During this procedure, a temperature of 45-500C is maintained. Stirring is continued at 450C for one hour. The melt is then dried in vacuo at 45--500C.
1. A process for the preparation of malachite green oxalate, which comprises reacting malachite green dyestuff base with oxalic acid in the melt.
2. A process according to claim 1, wherein the malachite green dyestuff base and oxalic acid are reacted in a molar ratio of 1:1.4-2.5.
3. A process according to claim 2 wherein the malachite green dyestuff base and oxalic acid are reacted in a molar ratio of 1 1.4 .#1 1.6.
4. A process according to any of claims 1 to 3 in which reaction takes place at a temperature in the range 40--700C.
5. A process according to claim 4 wherein the reaction takes place at 45--500C.
6. A process according to any of claims 1 to 5 wherein the reaction is carried out in the presence of 30100% by weight of water, based on the weight of the melt.
7. A process according to any of claims 1 to 6 wherein the oxalic acid is hydrated oxalic acid C2H204, 2H 20.
8. A process according to any of claims 1 to 7 wherein the malachite green oxalate produced is dried in vacuo at a temperature not exceeding 750C.
9. A process according to claim 1, substantially as described in the Example.
1 0. Malachite green oxalate, whenever prepared by a process according to any preceding claim.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Process for the preparation of malachite green oxalate The present invention relates to a process for the preparation of malachite green oxalate by reacting the dyestuff base of malachite green with oxalic acid in the melt. The dyestuff base and oxalic acid are preferably reacted in a molar ratio of 1:1.4-2.5, in particular 1:1.4-1.6, in the presence of at least 30100% by weight, and in particular 30-40% by weight (relative to the melt), of water. The water content datum relates to the total water present in the reaction mixture, that is to say that it also includes the water liberated during the neutralisation. The reaction temperature is preferably 40--700C, in particular 40--600C. A reaction temperature of 45-500C is to be especially mentioned. The oxalic acid is preferably used in the form of crystals having the composition C2H2 04. 2H2 0. In the process according to the invention, the water content and reaction temperature are adjusted such that a melt which is capable of flowing and can be stirred is formed at this temperature. The malachite green oxalate is dried at a maximum temperature of 750C, preferably at 45-500C, in vacuo. The process can be carried out industrially by a procedure such that the reaction and drying take place in the same reaction equipment (for example a vacuum paddle drier). However, it is also possible to carry out the reaction in a stirred container and to dry the resin under the given conditions by any desired industrial drying process. The known process, which can be used industrially, for the preparation of malachite green (Colour Index 42 000) comprises subjecting benzaldehyde to a condensation reaction with dimethylaniline, oxidising the leuco-base with lead dioxide, isolating the dyestuff as the Pb salt converting the lead salt into the dyestuff base, isolating the dyestuff base, dissolving the base in aqueous oxalic acid and crystallising out the oxalate. This process is described, for example, in Ullmanns Encyclopadie der techn. Chemie (Ullmanns Encyclopaedia of Industrial Chemistry), Volume 17 (1966), pages 666-667. The disadvantage of the process carried out on this basis is the large amount of water required for dissolving the dyestuff. To prepare an aqueous solution of malachite green oxalate which is saturated at 700 C, about four times the amount by weight of water is required. The mother liquor obtained after the crystallisation during isolation of the dyestuff pollutes the effluent and gives rise to a loss in yield. Surprisingly, it has now been found that a dyestuff of which the physical and coloristic properties are identical to the properties of the dyestuff which can be obtained by the known process is obtained by the new process, in which these disadvantages are avoided. In particular, it could not be predicted that the composition of the crystals of the dyestuffs prepared by the two processes would be stoichiometrically identical. Example 100 kg of moist malachite green dyestuff base (water content: 28.2%) are introduced into a container, which is warmed to 45 to 500C, whilst stirring, and 25 kg of crystalline oxalic acid (C2H204.2H2O) are added in the course of 5 minutes. After at most 10 minutes, the batch is mobile and homogeneous. A total of 1,600 kg of the dyestuff base and 400 kg of the crystalline oxalic acid are now added in portions. A further 223 kg of crystalline oxalic acid are then introduced into the mobile homogeneous mixture. During this procedure, a temperature of 45-500C is maintained. Stirring is continued at 450C for one hour. The melt is then dried in vacuo at 45--500C. CLAIMS
1. A process for the preparation of malachite green oxalate, which comprises reacting malachite green dyestuff base with oxalic acid in the melt.
2. A process according to claim 1, wherein the malachite green dyestuff base and oxalic acid are reacted in a molar ratio of 1:1.4-2.5.
3. A process according to claim 2 wherein the malachite green dyestuff base and oxalic acid are reacted in a molar ratio of 1 1.4 .#1 1.6.
4. A process according to any of claims 1 to 3 in which reaction takes place at a temperature in the range 40--700C.
5. A process according to claim 4 wherein the reaction takes place at 45--500C.
6. A process according to any of claims 1 to 5 wherein the reaction is carried out in the presence of 30100% by weight of water, based on the weight of the melt.
7. A process according to any of claims 1 to 6 wherein the oxalic acid is hydrated oxalic acid C2H204, 2H 20.
8. A process according to any of claims 1 to 7 wherein the malachite green oxalate produced is dried in vacuo at a temperature not exceeding 750C.
9. A process according to claim 1, substantially as described in the Example.
1 0. Malachite green oxalate, whenever prepared by a process according to any preceding claim.
GB8128953A 1980-09-25 1981-09-24 Process for the preparation of malachite green oxalate Expired GB2084604B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19803036078 DE3036078A1 (en) 1980-09-25 1980-09-25 METHOD FOR PRODUCING MALACHITE GREEN OXALATE

Publications (2)

Publication Number Publication Date
GB2084604A true GB2084604A (en) 1982-04-15
GB2084604B GB2084604B (en) 1984-06-06

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Family Applications (1)

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GB8128953A Expired GB2084604B (en) 1980-09-25 1981-09-24 Process for the preparation of malachite green oxalate

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JP (1) JPS5785856A (en)
DE (1) DE3036078A1 (en)
GB (1) GB2084604B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2322973C1 (en) * 2006-11-29 2008-04-27 Михаил Владимирович Кутушов Use of malachite green as drug in treatment of malignant neoplasm
WO2008066402A1 (en) * 2006-11-29 2008-06-05 Germanov, Evgeny Pavlovich Use of malachite green in the form of drug for treating malignant neoplasms

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2928466A1 (en) * 1979-07-13 1981-01-29 Bayer Ag METHOD FOR PRODUCING CATIONIC DYES

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2322973C1 (en) * 2006-11-29 2008-04-27 Михаил Владимирович Кутушов Use of malachite green as drug in treatment of malignant neoplasm
WO2008066402A1 (en) * 2006-11-29 2008-06-05 Germanov, Evgeny Pavlovich Use of malachite green in the form of drug for treating malignant neoplasms
US8436195B2 (en) 2006-11-29 2013-05-07 Evgeny Pavlovich Germanov Use of malachite green oxalate for treating malignant neoplasms

Also Published As

Publication number Publication date
DE3036078A1 (en) 1982-05-06
JPS5785856A (en) 1982-05-28
DE3036078C2 (en) 1988-07-07
GB2084604B (en) 1984-06-06
JPH0155305B2 (en) 1989-11-24

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