IE47264B1

IE47264B1 - Process for the preparation of morpholinodithiothiazoles

Info

Publication number: IE47264B1
Application number: IE1843/78A
Authority: IE
Original assignee: Bayer Ag
Priority date: 1977-09-14
Filing date: 1978-09-13
Publication date: 1984-02-08
Also published as: IT1106907B; DE2860619D1; JPS5448772A; EP0001098B1; ES473315A1; EP0001098A1; IE781843L; DE2741261A1; BR7805969A; IT7851052A0

Abstract

1. A process for the production of morpholino-dithiothiazoles of the general formula (I) : see diagramm : EP0001098,P7,F1 in which R represents a 2-benzthiazole or 2-naphthiazole radical which may optionally be substituted by straight-chain or branched-chain alkyl groups containing from 1 to 10 carbon atoms, by reacting compounds of the general formula (II) (R-S-)n M in which R has the meaning indicated above, M represents a metal ion of sodium, potassium, lithium, magnesium, calcium, boron or aluminium and n denotes an integer from 1 to 3, with morpholine, sulphur and an oxidising agent in the presence of a catalyst in a predominantly aqueous medium, characterised in that an aqueous solution of a mercaptothiazole salt of the above general formula (II) is used and acid is added to the mixture during the course of the reaction.

Description

The invention relates to a process for the preparation of morpholinodithiothiazoles hy reaction of an aqueous mercaptothiazole salt solution, morpholine and. sulphur with an oxidising agent, with addition of acid.

The preparation of morpholinodithiothiazole, using sodium hypochlorite, from mercaptothiazoles, morpholine and sulphur in alcohol, is known from the DE-AS (German Published Specification) 1,138,054. An excess of amine is necessary in this reaction, so that this io reagent is not completely exhausted.

According to the process of DE-OS (German Published Specification) 2,238,515, a mixture of mercaptobenzthiazole (MBT), morpholine, sulphur and solvent is treated with sodium hypochlorite solution (bleaching liquor), in which process, however, 150 parts by weight of water per 100 parts by weight of dry MBT may not be exceeded.

A similar process for the preparation of morpholino dithiothiazoles is known from U.S. Patent Specification 3,281,418, in which 2-mercaptobenzthiazole or 2,2’-bis(ben2thiazolyl) disulphide, morpholine and sulphur are heated together with the aqueous solution of a watersoluble oxidising agent, in an inert organic solvent.

In this process, the reaction temperature must be above the crystallisation tenperature of the reaction mixture, and the oxidising agent must be added, above all, very rapidly before the crystallisation of the morpholinodithiothiazole formed.

It has now surprisingly been found that morpholino30 dithiothiazoles can be prepared in good yields in preponderantly aqueous medium in a one-step process from a mercaptothiazole salt, morpholine and sulphur by direct oxidation, if an acid is added to the mixture in the course of the reaction. The aqueous solution of a salt of a mercaptothiazole is employed for the reaction. The reaction mixture contains a catalyst and can, in addition, , - 3 further contain minor quantities of an organic solvent.

The object of the invention is therefore a process for the preparation of morpholinodithiothiazoles of the general formula I ry W\_J> (I) wherein R denotes a 2-benzthiazole or 2-naphthia2ole radical, which can be optionally substituted by straightchain or branched alkyl groups with 1 to 10 C atoms, by reaction of compounds of the general formula II io (R-S-)nM (II) in which R has the meaning given above, M represents a metal ion of sodium, potassium, lithium, magnesium, calcium, boron or aluminium, and n denotes an integer from 1 to 3, with morpholine, sulphur and an oxidising agent in the presence of a catalyst in preponderantly aqueous medium, characterised in that an aqueous solution of a mercaptothiazole salt of the general formula II given above is euployed, and an acid is added to the mixture in the course of the reaction.

Suitable compounds of the general formula II (R-S-)nM (II) are, for example, those in which R denotes an unsubstituted benzthiazyl or naphthiazyl radical, or a henzthiazyl or naphthiazyl radical which is monosubstituted, disubstituted or mixed-substituted by methyl, ethyl, propyl, isopropyl, hexyl, pentyl, iso-octyl, nonyl anddocyl(si?)groups, and M denotes a metal ion of sodium, potassium, lithium, magnesium, calcium, boron or aluminium.

The sodium salts of the appropriate mercapto com30 pounds are preferably employed. The sodium salt of mercaptobenzthiazole is particularly preferred.

The concentration of the aqueous thiazole salt solution is 5 to 60% by weight, preferably 35 to 55% by weight.

The reaction is carried out in preponderantly - 4 aqueous medium. The quantity of water is not critical in this process. It can be varied within a wide range, and can be 50 to 1,000 parts by weight, preferably 80 to 300 parts by weight, particularly preferably 100 to 250 parts by weight, relative to 100 parts by weight of dry mercaptothiazole. > The ratio of morpholine and sulphur to the thiazole salt solution is, in the case of the morpholine, 30 to 200, preferably 50 to 150, parts by weight, in the case of the lo sulphur, 10 to 30, preferably 15 to 25 parts by weight, relative to 100 parts by weight of dry mercaptobenzthiazole.

An inorganic acid as.well as an organic acid can be employed as the acid. Particular examples of inor15 ganic acids which may be mentioned are: hydrochloric acid, sulphuric acid, nitric acid, phosphoric acid, hydrofluoric acid and perchloric acid.

Particular examples of organic acids which may be mentioned are: formic acid, acetic acid, propionic acid, oxalic acid, succinic acid, citric acid, tartaric acid, phthalic acid, benzoic acid and phenylacetic acid. The concentration of the acid added is 5 to 100% by weight.

The quantity of acid added is 0.01 to 2.0 mols, preferably 0.6 to 0.99 mol, relative to 1 mol of mercapto25 thiazole salt. Either the total quantity of the acid can be added at the beginning before the oxidation, or a part of the acid is added at the beginning and the rest is added in the course of the oxidation. In this case, 0.05 to 0.99 mol of acid per 1 mol of mercaptothiazole salt are added at the beginning and the rest in the course of the oxidation. It is to be presumed that in the course of the reaction, in contrast to the previously known processes, a direct oxidation of the mercaptothiazole salt with formation of the morpholinodithiothiazole also partially occurs. In addition, the end product is formed from the mercaptothiazole formed as an intermediate, as illustrated by the reaction equation further below.

All known and customary oxidising agents are suit47264 - 5 able as the oxidising agent, preferably those which can be employed, in the form of their aqueous solutions.

Examples which may be mentioned are: halogens, such as chlorine or bromine, hydrogen peroxide, sodium hypochlorite and sodium chlorate. Sodium hypochlorite is preferably used. ~ * The molar ratio of oxidising agent to mercaptothiazole salt is 3:1 to 1:1, preferably 1.9:1 to 1.2:1. Suitable organic solvents, which can be employed as cosolvents in the reaction mixture, are: aliphatic, cycloaliphatic and araliphatic alcohols with 1 to 15 carbon atoms, such as methanol, ethanol, propanol, isopropanol, butanols, pentanols, hexanols, decanols, benzylalcohol, cyclohexanol and cyclopentanol, aliphatic, cycloaliphatic and aromatic hydrocarbons with 5 to 15 carbon atoms, such as pentane, hexane, heptane, octane, dodecane, cyclohexane, benzene, toluene and xylene, as well as ethers and esters.

If the reaction is carried out without a co-solvent, a small quantity of a customary emulsifier or dispersing agent has proved to be advantageous.

Primary or secondary aliphatic and cycloaliphatic or secondary heterocyclic amines, acid amides, or mixtures thereof, are employed as catalysts.

The following are preferably employed: methylamine, dimethylamine, cyclohexylamine, dicyclohexylamine, piperidine, ethylamine, diethylamine, propylamine, butylamine and dimethylformamide. The addition of the catalyst is effected in a measure of 0.01 to 300 parts by weight, preferably of 0.03 to 12 parts by weight, relative to 100 parts by weight of the thiazole compounds.

The reaction proceeds at temperatures between 20 to 12O°C; the temperature is expediently kept between 40°C and75°C. The reaction can be carried out isothermally or at different temperatures in a temperature range of 20 to 120°C. The upper limit of the reaction temperature is determined in this process by the boiling point of the aqueous phase or of the solvent mixture.

The point in time of the crystallisation of the morpholinodithiothiazole formed has no effect on its 47864 - 6 purity and yield. The crystallisation can take place during the total course of the oxidation, without adversely affecting the properties of the product. ‘The morpholinodithiothiazoles prepared according to the process according to the invention are obtained in good yield and high purity. « . y The follovzing equation illustrates the reaction · for the example of the sodium salt of mercaptobenzthiazole, using sodium hypochlorite as oxidising agent.

The compounds prepared according to the invention are suitable, inter alia, for accelerating the vulcanisation of natural and/or synthetic rubbers.

The product formed in the reaction is distingui15 shed by a fine grain, so that it can be processed well technologically without grinding.

In the following examples, the per cent data are always % by weight.

Exanple 1 The following are initially introduced into a stirring apparatus: 120.1 g of a 50.2% strength aqueous solution of sodium mercaptobenzthiazole (NaMBT), corres- ponding to 53.3 g (0.319 mol) of mercaptobenzthiazole (MBT). 27.7 g (0.31S mol) morpholine 10.0 g (Ο.313 mol) sulphur 0.65 g Cyclohexylamine 72 ml Isopropanoi (100% strength) 13 ml Water ml (0.26 mol of HCl) of 30% strength hydrochloric acid are added to the mixture at 59°C, whereafter - Ί the reaction mixture has a pH value of 7.8. 215 ml (0.46 mol), of an approximately 14% strength hy weight sodium hypochlorite solution are then added to the mixture in the course of 35 minutes, and morpholinodithio5 benzthiazole begins to be precipitated as a yellow precipitate after addition of about 125 ml. During,the addition, the temperature rises out of (sic) 74°C.

After the reaction has ended, the precipitate is filtered off, and is washed with twice 100 ml of iso10 propanol and with 4 times 200 ml of water.

Yield: 75.5 = 83.3% (relative to MBT employed) Melting point: 120 to 131°C Purity: 95.1%.

Example 2 15 The following are initially introduced into a stirring apparatus: 120.1 g NaMBT (50.2% strength by weight aqueous solution) = 53.3gMBT (0.319 mol) 20 72 ml Isopropanoi 100% strength ml Water 27.7 g (0.318 mol) morpholine 0.65 g eyclohexylamine 10.0 g (0.313 mol) sulphur 25 15.5 ml (0.147 mol of HCl) of 30% strength hydrochloric acid are added to the mixture at 58°C (pH = 8.7). The solution contains 158 parts by weight of water to 100 parts by weight of MBT. 198 ml (approximately 0.42 mol) of sodium hypochlorite solution (approximately 14% strength by weight) are added to the mixture in measured quantities in the temperature range of 58 to 73°C in the course of 33 minutes, whilst 10.2 ml (0.096 mol of HCl) of 30% strength hydrochloric acid are added at the same time. In this process, the tenperature rises to 74°C.

After the reaction mixture has cooled to room temperature, the morpholinodithiobenzthiazole, which began to be precipitated after addition of about half of the sodium hypochlorite solution, is filtered off, and 47364 - 8 is washed with twice 100 ml of isopropanol and with five times 200 ml of water, and dried.

Yield: 73.6 = 81% (relative to MBT employed) Melting point: 129 to 131°C Purity: 96.6%.

Example 3 The following have been introduced into a stirring apparatus: 116.9 g NaMBT (51.6% strength by weight solution) = 53.3 g MBT (0.319 mol) 55.7 g Morpholine 0.65 g Cyclohexylamine .0 g Sulphur g of 96% strength sulphuric acid (0.29 mol) are added to the mixture at 58 °C.’ 170 ml (0.32 mol) of sodium hypochlorite solution (approximately 14% strength by weight) are added in measured quantities to the mixture in the temperature range of 58 to 74°C, morpholinodithiobenzthiazole being precipitated as a yellow precipitate after metered addition of 140 ml. After the mixture has cooled, the precipitate is filtered off and 12 mols (sic) are washed v/ith 120 ml of water.

Yield: 84.5 to 93.3% (relative to MBT employed) Melting point: 125 to 131°C Content: 96.1%.

Examples 4 to 24 The Examples 3 to 22 show the effect of various amounts and types of metered addition of several acids on yield and purity of the morpholinodithiobenzthiazole.

In these processes, the starting material is alv/ays an aqueous sodium mercaptobenzthiazole solution (in general, approximately 50% strength with 53.3 g of MBT = 0.319 mol, corresponding to approximately 120 g of solution). In general, 85 ml of an isopropanol/HgO mixture (corresponding to an 85% strength azeotropic mixture of isopropanol/ H^O), 27.7 g (0.318 mol) of morpholine, 0.65 g of cyclohexylamine and 10 g of sulphur (0.313 mol)have been (sic) successively added to the solution. After the mixture has been warmed to 55 to 60°C, either the total amount or the first part (see table) of the acid is added.

The sodium hypochlorite solution (in general, an excess of 30 to 70 mol %) is then added in measured quantities to the mixture in the course of about 30 minutes, and, if appropriate, the second part of the acid is added at the same time. The morpholinodithiothiazole is precipitated, in general after half the metered addition,as a slightly yellow coloured solid. The reaction data of Examples 4 to 24 are summarised in the table which follows. 47864 Η -Γ*· β Tfc Ή *-* *1 ϋ* -η-ρ ♦» c „ cj*3 ,Ρ Θ Ο Ο £ Ρ» °*2§ •d α βη ΡΌ_ τί·&ίί C &ο CU.G β ΡΗΗ S’SS *2-0 -P-3-rt α >»ο ηλ α νο-3·ί-κ\σ^ί<Γ<τ ΚΝΟ9Ν0<Γ K'vK'NCM m tAtrtcp β © Φ e-c* fr-H ON KN KN C*-CO «Λ ® ONfr»NOOltfNeOcO 0» On ON ON ON On ON On ΚΝιΓΝΗ HOWrt mnw to cm m mm HrtriHrtrtrtH I 1 J I 1 I I I t^o o on on on co co N^WWHWCVW HrlrtriHHrlrH ONOKNNONO OiA NO ΚΜΠΚΝίΓΝΚΝί'-ΟrlHrlriHrtrlH CM th CO cooconocOOOOOOOO H W tn

Claims

1. Process for the preparation of moipholinodithiothiazoles of the general formula I (I) 5 wherein R denotes a 2-benzthiazole or 2-naphthiazole radical, which can be optionally substituted by straightchain or branched alkyl groups with 1 to 10 C atoms, by reaction of compounds of the general formula II (II) lo in which R has the meaning given above, M represents a metal ion of sodium, potassium, lithium, magnesium, calcium, boron or aluminium, and n denotes an Integer from 1 to 3, with morpholine, sulphur and an oxidising agent in the presence of a catalyst in preponderantly aqueous 15 medium, characterised in that an aqueous solution of a mercaptothiazole salt of the general formula II given above is employed and acid is added to the mixture in the course of the reaction.

2. Process according to Claim 1, characterised in 20 that the quantity of acid is 0.01 to 2.0 mols, relative to 1 mol of mercaptothiazole salt.

3. Process according to Claim 1, characterised in that an inorganic acid is added to the reaction mixture.

4. Process according to Claim 1, characterised in 25 that hydrochloric acid or sulphuric acid is added to the reaction mixture.

5. Process according to Claim 1, characterised In that the total quantity of acid is added to the reaction mixture before the oxidation. 30

6. Process according to Claim 1, characterised in that 0.05 to 0.99 nol of acid, relative to 1 mol of mercaptothiazole salt, is added to the reaction mixture - 12 10 before the oxidation, and the rest of the acid in the course of the oxidation.

7. Process according to Claim 1, characterised in that a sodium or calcium salt of the mercaptothiazole is employed.

8. Process according to Claim 1, characterised in that an amine is employed as the catalyst.

9. Process according to Claim 1, characterised in that the reaction is carried out using an organic solvent as the co-solvent,

10. Process according to Claim 1, characterised in that an aliphatic alcohol with 3 to 5 carbon atoms is used as the organic solvent.

11. Process according to Claim 1, characterised in that, in the absence of the organic solvent, a small quantity of a customary emulsifier or dispersing agent is employed.

12. Process according to Claim 1, characterised in that the quantity by weight of morpholine, relative to 100 parts by weight of dry mercaptothiazole, is 30 to 200, preferably 50 to 150, parts by weight.

13. Process according to Claim 1, characterised in that the quantity by weight of water, relative to 100 parts by weight of dry mercaptothiazole, is 50 to 1,000 parts by weight.

14. A process ’for the production of a irorpholino-aitniothiazole of the general formula X given and defined in Claim 1 substantially as hereinbefore described with reference to the accompanying Examples.

15. A morpholino-dithiothiazole of the general formula I given and defined in Claim 1 whenever produced by a process claimed in a preceding Claim.