GB2081705A - Preparation of Thiones - Google Patents
Preparation of Thiones Download PDFInfo
- Publication number
- GB2081705A GB2081705A GB8025535A GB8025535A GB2081705A GB 2081705 A GB2081705 A GB 2081705A GB 8025535 A GB8025535 A GB 8025535A GB 8025535 A GB8025535 A GB 8025535A GB 2081705 A GB2081705 A GB 2081705A
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- GB
- United Kingdom
- Prior art keywords
- process according
- alkyl
- thione
- substituted alkyl
- general formula
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D293/00—Heterocyclic compounds containing rings having nitrogen and selenium or nitrogen and tellurium, with or without oxygen or sulfur atoms, as the ring hetero atoms
- C07D293/10—Heterocyclic compounds containing rings having nitrogen and selenium or nitrogen and tellurium, with or without oxygen or sulfur atoms, as the ring hetero atoms condensed with carbocyclic rings or ring systems
- C07D293/12—Selenazoles; Hydrogenated selenazoles
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D231/00—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings
- C07D231/02—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings
- C07D231/10—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
- C07D231/14—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D231/18—One oxygen or sulfur atom
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
- C07D277/60—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings condensed with carbocyclic rings or ring systems
- C07D277/62—Benzothiazoles
- C07D277/64—Benzothiazoles with only hydrocarbon or substituted hydrocarbon radicals attached in position 2
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
Abstract
The production of a thione compound of the general formula I:- <IMAGE> where R1 is an alkyl, substituted alkyl or an aryl group and R2 is an alkyl or substituted alkyl group or R1 and R2 together represent the atoms necessary to complete a heterocyclic ring, comprises reacting a ketone of the general formula II:- <IMAGE> with a molar excess of phosphorus pentasulphide and an alkali metal or alkaline earth base in a solution of a cyclic ether at a pH between 8.4 and 12. The thiones of the examples are of use in the production of optical sensitizing dyes.
Description
SPECIFICATION
Preparation of Thiones
This invention relates to the preparation of thione compounds from the corresponding ketones.
Thione compounds are extremely useful as intermediates in the preparation of complex chemical compounds because of their greater reactivity compared with their more stable ketone analogues.
Various methods have been proposed and used for converting ketones to the analogous thiones but often dark intractable tars are the result of such a reaction.
It is the object of the present invention to provide a simple method of converting ketones to the analoyous thione compounds in which the possibility of producing an unusable tar is considerably reduced.
According to the present invention there is provided a process for the production of a thione compound of the general formula I:
where R1 is an alkyl, substituted alkyl or an aryl group and R2 an alkyl or substituted alkyl group or R and R2 together represent the atoms necessary to complete a heterocyclic ring, which comprises reacting a ketone of the general formula Il:-
where1 and R2 have the meanings assigned to them above with a molar excess of phosphorus pentasulphide and an alkali metal or alkaline earth base in a solution of a cyclic ether at a pH between 8.4 and 12.
Preferably the pH is about 9.0.
Preferably the reaction is carried out at an elevated temperature between 50 and 700C. However in some instances and especially when the ketone of formula II which is used as the starting material is 3,31-trimethylpyrazolo-2-one the reaction is carried out at a higher elevated temperature. Nevertheless this reaction should not be carried out at a temperature greater than 850C to prevent the formation of tar.
The preferred cyclic ether to be used as the solvent in which to carry out the reaction is dioxan.
Another suitable solvent is tetrahydrofuran.
The preferred alkali metal or alkaline earth bases for use in the process of the present invention are sodium carbonate, calcium hydroxide, barium hydroxide and barium carbonate.
Preferably a mineral acid is used to isolate the thione from the reaction mixture and most preferably this is hydrochloric acid.
The process of the present invention is of particular use in the preparation of compounds of the general formula Ill:-
where R, has the meaning assigned to it above, R3 is an optionally substituted alkyl or aryl group, R4 and R5 are each hydrogen or halogen atoms or optionally substituted alkyl or aryl groups or the group -CF3, orR4 and R5 represent benzannelation, X is -NR6-,-S-, -Se-or -CR7R8 where R6 is hydrogen or an alkyl group and R7 and R8 are each halogen atoms or alkyl groups having from 1 to 4 carbon atoms.
The compounds of formula Ill are of particular use in the preparation of carbocyanine dyes used to spectrally sensitize photographic silver halide emulsions.
Examples of such a reaction are given, for example, in Hamer, "Cyanine Dyes and Related
Compounds", Interscience, 1954, Chapter 6.
It is to be understood that the name phosphorus pentasulphide is the common name of the compound tetraphosphorus decasulphide which is used in the process of the present invention.
The following Examples will serve to illustrate the invention.
Example 1 5-Chloro-3-ethyl-2-thiopropionylmethylene Benzothiazole
5-(\hloro-3-ethyl-2-thiopropionylmethylene benzothiazole (378 g, 1 .4M) was transferred into a multinecked flask equipped with overhead stirrer, reflux-condenser, thermometer and dropping funnel.
The solid was treated with phosphorus pentasulphide (187 g), calcium hydroxide (730 g) and dioxan (5 litres) and the resulting mixture was stirred (pH 8.8) and heated on a water-bath at an internal temperature of 65-700C for a period of 4 hours. A bright orange solution was obtained containing the colourless calcium salts. The mixture was allowed to cool overnight too room temperature and the brightiorange dioxan solution was filtered free of the inorganic salts using a filter stick (porosity 0). The inorganic salts were triturated with dioxan (1.5 litres) and the dioxan removed as before.
Evaporation of the combined filtrates on a rotary evaporator at 500C/20 mm afforded an orange solid which was triturated for 1 hour with water (1.2 litres) containing concentrated hydrochloric acid (20 ml). The bright orange crystalline solid was filtered, washed with water (1 litre) and dried in a forced air oven at 400C for 24 hours. Yield: 320 g (79%). Melting point 1 53-1 550C.
Example 2 3-Ethyl-5-methyl-2-thiopropionylmethylene Benzoselenazoline
3-Ethyl-5-methyl-2-propionylmethylene benzoselenazoline (885 g, 5 moles) was transferred into a 20 litre reaction vessei equipped with stirrer, dropping funnel, thermometer and reflux condenser. To the solid in the flask, phosphorus pentasulphide (360 g) and sodium carbonate (1,980 g) were added. This was followed by the addition of dioxan (4.8 litres) and the resulting mixture was stirred and cautiously heated on a steam bath at 400C whereupon the mixture became exothermic and the internal temperature rose to 500 C. The resulting mixture was then stirred and heated (pH 9.0) to 55-600C for 0.5 hour and 65-700C for 2 hours.When a tic sample indicated that the reaction was complete (eluant:-diethyl ether), the mixture was cooled to an internal temperature of 45 or. Ice cold water (11 litres) was added portionwise to the stirred mixture in the 20 litre vessel. Some frothing had occurred and an orange solid precipitated when the addition of water was complete. The solid was filtered at 200C in the flask using a filter stick (porosity 0). When as much liquors as possible were removed, the solid in the flask was treated with water (11 litres), stirred for 0.25 hour and the aqueous liquors removed with the aid of a filter stick. The solid was finally treated with water (11 litres), stirred for 0.25 hour and filtered on a short base minifilter under vacuum. The solid was washed on the filter with water (2x2 litres) and then transferred to a forced air oven and dried at 500C for 24 hours. Yield: 874 g (94%). Melting point 129--1360C, Orange crystalline solid.
Example 3 3-Ethyl-2-thioacetylmethylene Benzothiazoline
2-Acetylmethylene-3-ethylbenzothiazoline (430 g, 2.7 moles) was transferred into a 10 litre multinecked flask equipped with a stainless steel stirrer, reflux condenser, dropping funnel and thermometer. Phosphorus pentasulphide (430 g), sodium carbqnate (1,080 g) and dioxan (3,250 ml) were then added and the resulting mixture was stirred and heated on (pH 9.0) a steam bath at an internal temperature of 60-700C for 5 hours. When a small sample of the reaction mixture was tested on tic and it was confirmed that the reaction was complete the contents of the flask were cooled to 250C. Water (6.8 litres) was added cautiously to the stirred mixture whereupon a dark brown solid precipitated.The dioxan/water liquors were removed using a filter stick (porosity 0) and to the solid in the flask water (7.0 litres) was added. The mixture was stirred for 0.5 hour and the water removed as before. Finally the product was triturated with water (3 litres) and filtered on a short base minifilter. The solid was washed on the filter with water (3 x 5,000 ml) and dried overnight in a forced air oven at 500C. Yield: 530 g (84%). Melting point 1 40--1 48 OC.
Example 4 3,3'-Trimethylpyrazolothio-2-one
3,3',4-Trimethyl pyrazolone (1,260 g, 10 moles), phosphorus pentasulphide (700 g, 1 5.76 moles) and barium carbonate (450 g, 2.28 moles) were added to a 20 litre multinecked flask equipped with an efficient reflux condenser, overhead stirrer and thermometer. This was followed by the addition of dry dioxan (1,260 ml, pre-dried over Drierite) and the resulting mixture was stirred and heated (pH 8.4) on a steam bath at 850C for 1 hour. (TIc indicated that the reaction was complete). An efficient aqueous sodium hydroxide trap was used to absorb any gaseous sulphur compounds that were evolved.After heating for a period of 1 hour the phosphorus pentasulphide/barium carbonate coagulated in the form' of granules, thereby permitting easy filterability of the dioxan via a filter stick (porosity 0). The phosphorus pentasulphide/barium carbonate residue was washed with dioxan (3x700 ml) and the combined filtrates were evaporated under reduced pressure (bath temperature 400C) in a rotary evaporator. Upon evaporation of the solvent a crystalline yellow solid was obtained. The solid was dissolved in aqueous sodium hydroxide (prepared from 480 g sodium hydroxide and 8 litres of water) and the turbid solution filtered through a fine grain filter paper. The clear, colourless, odourless filtrate was stirred and acidified to pH 4.0 with hydrochloric acid (S.G. 1.1 6) over a period of 2 hours. The product precipitated as a colourless crystalline solid and was filtered off, washed with water to pH 7.0 and dried at 400C in a well-ventilated oven. Yield: 1,213 g (85%). Melting point 1 07.90C.
Claims (11)
1. A process for the production of a thione compound of the general formula I:
where R1 is an alkyl, substituted alkyl or an aryl group and R2 is an alkyl or substituted alkyl group or R1 and R2 together represent the atoms necessary to complete a heterocyclic ring, which comprises reacting a ketone of the general formula Ilt
where R1 and R2 have the meanings assigned to them above with a molar excess of phosphorus pentasulphide and an alkali metal or alkaline earth base in a solution of a cyclic ether at a pH between 8.4 and 12.
2. A process according to claim 1 wherein the pH at which the reaction is carried out is about 9.0.
3. A process according to either claim 1 or claim 2 wherein the cyclic ether is dioxan.
4. A process according to any one of claims 1 to 3 wherein the reaction is carried out at an elevated temperature between 50 to 700 C.
5. A process according to any one of claims 1 to 4 wherein the alkali metal base is sodium carbonate.
6. A process according to any one of claims 1 to 4 wherein the alkaline earth base is calcium hydroxide, barium hydroxide or barium carbonate.
7. A process according to any one of claims 1 to 6 wherein a mineral acid is used to isolate the thione from the reaction mixture.
8. A process according to claim 7 wherein the mineral acid is hydrochloric acid.
9. A process according to any one of claims 1 to 8 wherein the thione produced is a compound of the general formula Ill:-
where R1 has the meaning assigned to it in claim 1, R3 is an optionally substituted alkyl or aryl group, R4 and R5 are each hydrogen or halogen atoms or optionally substituted alkyl or aryl groups or the group -CF3, or R4 and R5 represent benzannelation, X is -NR8-, -S-, -Se- or -CR 7R8 where R6 is hydrogen or an alkyl group and R7 and R8 are each halogen atoms or alkyl groups having from 1 to 4 carbon atoms.
10. A process for the production of a thione compound according to claim 1 substantially as hereinbefore described with reference to the accompanying Examples.
11. A thione of formula I as defined in claim 1 which has been prepared by a process claimed in any one of claims 1 to 10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8025535A GB2081705A (en) | 1980-08-06 | 1980-08-06 | Preparation of Thiones |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8025535A GB2081705A (en) | 1980-08-06 | 1980-08-06 | Preparation of Thiones |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2081705A true GB2081705A (en) | 1982-02-24 |
Family
ID=10515256
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8025535A Withdrawn GB2081705A (en) | 1980-08-06 | 1980-08-06 | Preparation of Thiones |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2081705A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7786151B2 (en) * | 2004-01-09 | 2010-08-31 | Kinopharma, Inc. | Therapeutic composition of treating abnormal splicing caused by the excessive kinase induction |
-
1980
- 1980-08-06 GB GB8025535A patent/GB2081705A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7786151B2 (en) * | 2004-01-09 | 2010-08-31 | Kinopharma, Inc. | Therapeutic composition of treating abnormal splicing caused by the excessive kinase induction |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |