Claims:1. A process for preparing cobalt boron acylate, the process comprising:
mixing neodecanoic acid, cobalt hydroxide and tributyl borate in a molar ratio in the range of 3:3.5:1 to 3.1:3.6:1.1, at a temperature in the range of 110-150 °C for 20-40 minutes to obtain a mixture;
adding acetic acid in a molar ratio in the range of 3.1:1.0 to 3.2:1.1 of tributyl borate to the mixture to obtain a second mixture;
refluxing the second mixture at a temperature in the range 110-150 °C for 10-30 minutes to obtain a solution containing cobalt boron acylate complex; and
obtaining cobalt boron acylate from the solution containing cobalt boron acylate complex.

2. The process as claimed in claim 1, wherein neodecanoic acid, cobalt hydroxide and tributyl borate are mixed under continuous stirring.

3. The process as claimed in claim 1, wherein acetic acid is added to the mixture in a molar ratio in the range of 3.1:1 to 3.2: 1.1 to obtain the second mixture.

4. The process as claimed in claim 1, wherein cobalt boron acylate is obtained from the solution containing cobalt boron acylate complex by
adding calcium metaborate in a molar ratio in the range of 0.3-0.6 with respect to tributyl borate to the solution containing cobalt boron acylate complex and refluxing at a temperature in the range of 150 to 200 °C for 5 to 20 minutes to obtain a solution containing cobalt boron acylate;
distilling the solution containing cobalt boron acylate at a temperature in the range of 200 to 215 °C for 20-30 minutes under vacuum; and
obtaining cobalt boron acylate.

5. The process as claimed in claim 1, wherein cobalt boron acylate is obtained from the solution containing cobalt boron acylate complex by distilling the solution containing cobalt boron acylate complex at a temperature in the range of 200 to 215 °C for 20-30 minutes under vacuum.

6. The process as claimed in claim 4, wherein calcium metaborate is added in a molar ratio in the range of 0.4 -0.5 with respect to tributyl borate to the solution containing cobalt boron acylate complex.

7. The process as claimed in claim 4 or 5, wherein the distillation is carried under vacuum at a pressure in the range of 102-103 mbar.

8. The process as claimed in claim 1, wherein the melting point of cobalt boron acylate is in the range of 90-98 °C.

9. The process as claimed in claim 1, wherein the cobalt content in cobalt boron acylate is in the range of 22-23%.

10. The process as claimed in claim 1, wherein the yield of cobalt boron acylate is in the range of 89-95%.
, Description:TECHNICAL FIELD
The present disclosure relates to a process for preparing cobalt boron acylate. Specifically, the present disclosure relates to a solvent free process for preparing cobalt boron acylate.

BACKGROUND
Cobalt boron acylate is used as an adhesion promoter in radial tires, conveyor belts, and other rubber bonding applications. It enhances the bonding of natural and synthetic rubber to steel cords, cables, metal plates, zinc bar, copper, and brass coatings. For use as an adhesion promoter in rubber industry, the melting point of cobalt boron acylate is one of the critical parameters. The variation in the melting point of cobalt boron acylate affects the dispersibility and mixing of the product in the rubber compound. Several processes for preparing cobalt boron acylate are known in the art.

CN103113416A discloses a process of preparing cobalt boron acylate by mixing neodecanoic acid, propionic acid, valeric acid, stearic acid, rosin, dimethylbenzene, and cobalt hydroxide to form a mixture at 85-95°C. The mixture is vacuum distilled at 155-165°C to remove xylene and water. To the distilled mixture, tributyl borate and calcium borate are added simultaneously. The mixture is then refluxed at 160-180 °C for 60 to 120 minutes followed by vacuum distillation to obtain cobalt boron acylate.

CN107011369A discloses a process that involves heating a mixture of cobalt hydroxide and propionic acid in a sealed container at 100-150 °C for more than 2 hours. To the heated mixture, neodecanoic acid and stearic acid are added and heated for 2 hours to obtain a salt mixture. To the obtained salt mixture, tributylborate is added. The mixture is then heated to 190-195°C for 1 hour to obtain cobalt boron acylate.

CN101643480B discloses a process that involves mixing neodecanoic acid, isooctanoic acid, glacial acetic acid, dimethylbenzene, and cobalt hydroxide at 85-95 C to obtain an intermediate product. To the obtained intermediate product, tributyl borate and calcium borate are added simultaneously for 60 to 120 minutes. The mixture is then refluxed at 160-180 °C followed by vacuum distillation to obtain cobalt boron acylate.

In the known processes there is a possibility of formation of a polymeric network of cobalt carboxylate complex (an intermediate product), which increases the viscosity of the intermediate product. The increased viscosity of the intermediate product causes difficulty in proper mixing during the reaction and therefore, additional solvents are required. Some of the conventional processes also require long reaction time and high temperature. Further, the known processes generally yield cobalt boron acylate having a high melting point, which is not suitable for use in the rubber industry.

SUMMARY
The present disclosure relates to a process for preparing cobalt boron acylate, the process comprising mixing neodecanoic acid, cobalt hydroxide and tributyl borate in a molar ratio in the range of 3:3.5:1 to 3.1:3.6:1.1, at a temperature in the range of 110-150 °C for 20-40 minutes to obtain a mixture; adding acetic acid in a molar ratio in the range of 3.1:1.0 to 3.2:1.1 of tributyl borate to the mixture to obtain a second mixture; refluxing the second mixture at a temperature in the range 110-150 °C for 10-30 minutes to obtain a solution containing cobalt boron acylate complex; and obtaining cobalt boron acylate from the solution containing cobalt boron acylate complex.

BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 depicts the Thermal Gravimetric Analysis (TGA) of cobalt boron acylate in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the disclosed composition and method, and such further applications of the principles of the disclosure therein being contemplated as would normally occur to one skilled in the art to which the disclosure relates.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the disclosure and are not intended to be restrictive thereof.

Reference throughout this specification to “one embodiment”, “an embodiment” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrase “in one embodiment”, “in an embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

The terms “a,” “an,”, and “the” are used to refer to “one or more” (i.e. to at least one) of the grammatical object of the article.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion and are not intended to be construed as “consists of only”, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods, and materials are now described.

The present disclosure relates to a process for preparing cobalt boron acylate. The process comprises mixing neodecanoic acid, cobalt hydroxide and tributyl borate in a molar ratio in the range of 3:3.5:1 to 3.1:3.6:1.1, at a temperature in the range of 110-150 °C for 20-40 minutes to obtain a mixture; adding acetic acid in a molar ratio in the range of 3.1:1.0 to 3.2:1.1 of tributyl borate to the mixture to obtain a second mixture; refluxing the second mixture at a temperature in the range 110-150 °C for 10-30 minutes to obtain a solution containing cobalt boron acylate complex; and obtaining cobalt boron acylate from the solution containing cobalt boron acylate complex.

In the disclosed process, neodecanoic acid, and cobalt hydroxide react to form a cobalt-neodecanate complex. The cobalt neodeconate complex reacts with boron trioxide generated from the reaction of acetic acid and tributyl borate to form the solution containing cobalt boron acylate complex.

Neodecanaoic acid, cobalt hydroxide and tributyl borate can be mixed together sequentially in any order or simulanteously. In an example, neodecanaoic acid and cobalt hydroxide are mixed prior to the addition of tributyl borate. In accordance with an embodiment, neodecanaoic acid, cobalt hydroxide and tributyl borate are mixed under continuous stirring.

In an embodiment, acetic acid is added to the mixture in a molar ratio in the 3.1:1 to 3.2:1.1 to obtain the second mixture. In accordance with an embodiment, acetic acid has a concentration in the range of 95-98%w/v.

In accordance with an embodiment, the process of mixing of neodecanoic acid, cobalt hydroxide and tributyl borate is carried out at a temperature is in the range of 110-120°C

In an embodiment, the process is carried out for 80-110 minutes. In a specific embodiment, the process is carried out for about 90 minutes.

The solution containing cobalt boron acylate complex contains cobalt boron acylate and by products. Said by products may include water and butyl acetate. In an embodiment, cobalt boron acylate is obtained from the solution containing cobalt boron acylate complex by distilling the solution containing cobalt boron acylate complex at a temperature in the range of 200-215°C for 20-30 minutes under vacuum. The distillation of the solution containing cobalt boron acylate complex separates cobalt boron acylate from butyl acetate and water.

In accordance with a specific embodiment, cobalt boron acylate is obtained from the solution containing cobalt boron acylate complex by adding calcium metaborate in a molar ratio in the range of 0.3-0.6 with respect to tributyl borate to the solution containing cobalt boron acylate complex and refluxing at a temperature in the range of 150 to 200 °C for 5 to 20 minutes to obtain a solution containing cobalt boron acylate, distilling the solution containing cobalt boron acylate at a temperature in the range of 200 to 215 °C for 20-30 minutes under vacuum, and obtaining cobalt boron acylate.

Calcium metaborate is added to the solution containing cobalt boron acylate complex to neutralize the neodecanoic acid, acetic acid and to increase boron concentration in cobalt boron acylate. In accordance with an embodiment, calcium metaborate is added in a molar ratio in the range of 0.4 to 0.5 with respect to tributyl borate to the solution containing cobalt boron acylate complex.

Any suitable distillation method may be used for distilling the solution containing cobalt boron acylate complex or the solution containing cobalt boron acylate. Examples of suitable method include but are not limited to simple distillation, fractional distillation, steam distillation, distillation under vacuum, and zone distillation. In accordance with a specific embodiment, the distillation is carried out under vacuum at a pressure in the range of 102-103 mbar.

In accordance with an embodiment, the distillation of the solution containing cobalt boron acylate separates butyl acetate and water and cobalt boron acylate is obtained. In accordance with an embodiment, cobalt boron acylate is obtained as a molten mass.

The obtained molten mass of cobalt boron acylate may be be subjected to further processing according to conventional methods or techniques, for example pelletization at a temperature in the range of 200-215°C.

In an embodiment, the obtained cobalt boron acylate is dried and ground to obtained cobalt boron acylate in a powder form. The grinding may be carried out in any suitable apparatus for grinding. Such apparatus includes but is not limited to mortar mills, vibrator mills or ball mills.

In accordance with an embodiment, cobalt boron acylate obtained from the disclosed process has melting point in the range of 90-98 °C.

In accordance with an embodiment, cobalt boron acylate obtained from the disclosed process has cobalt content in the range of 22-23%.

In accordance with an embodiment, the yield of cobalt boron acylate obtained from the disclosed process is in the range of 89-95%.

EXAMPLES
The following examples are provided to explain and illustrate the preferred embodiments of the present disclosure and do not in any way limit the scope of the disclosure as described:

Example 1: Synthesis of cobalt boron acylate according to the known process of the prior art: 26.71 g of neodecanoic acid, 9. 11 g of acetic acid, and 14.98 g of cobalt hydroxide were taken in a 250 ml of three-necked round bottom flask to form a cobalt carboxylate complex. The reaction flask was fitted with an appropriate condenser cooled with water circulation and a vacuum pump. The temperature was set at 125 oC with a stirring rate of ~200 rpm. 25 ml of xylene was separately measured and added into the cobalt carboxylate complex to form a mixture. The mixture was refluxed for 35 minutes. Thereafter, the generated water was removed from the mixture by distillation under vacuum 102-103 mbar at 160 oC for 35-65 minutes. 12.95 ml of tributyl borate was measured and added into the distilled mixture to form a solution. The solution was refluxed at 200 oC for 65-95 minutes under constant stirring. Thereafter, the solution was distilled under vacuum at 102-103 mbar 200 oC for 95-110 minutes to remove by products like butyl acetate. The distilled solution was heated at 208 oC for 20-30 minutes to obtain cobalt boron acylate.

Example 2: Synthesis of cobalt boron acylate in accordance with an embodiment of the present disclosure: 25.02 gm of neodecanoic acid, 11.8 gm of tributyl borate and 15.45 gm of cobat hydroxide were taken in a 250 ml of three necked round bottom flask to obtain a mixture. The reaction flask was fitted with an appropriate condenser cooled with water circulation. The temperature was set at 120±5 oC with a stirring rate of ~200±10 rpm. Thereafter, the mixture was refluxed for 30 minutes. 8.5 ml of acetic acid was measured separately and added into the mixture to form a second mixture. The second mixture was refluxed at 125 oC for 15 minutes under constant stirring to obtain a solution containing cobalt boron acylate complex. 3.0 gm of calcium metaborate was weighed and added to the solution containing cobalt boron acylate complex. The temperature of the reaction flask was then raised slowly. Once the temperature reached 180 oC, the solution containing cobalt boron acylate complex was refluxed at 180 oC for 15 minutes to obtain a solution containing cobalt boron acylate. The solution of cobalt boron acylate was then subjected to distillation under vacuum at a pressure of 102 mbar at 205 oC for 15 minutes. Thereafter, the distilled solution was heated at a temperature of 208 oC for 5-10 minutes. Cobalt boron acylate was obtained from the distilled solution. Post synthesis, a detailed characterization of the synthesized cobalt boron acylate was carried out. The properties were tabulated in table 1.

A. Properties of cobalt boron acylate prepared in accordance with the present disclosure: Table 1 below provides properties of cobalt boron acylate prepared in accordance with the present disclosure. FIG. 1 depicts the Thermal Gravimetric Analysis (TGA) of cobalt boron acylate.

Table 1: Properties of cobalt boron acylate of the present disclosure
Properties Unit Cobalt Boron acylate
Cobalt content % 22.5
Melting point ° C 94
Heptane insolubility % < 7
Heat loss % 0.18
Specific gravity* (25 °C) Powder form 0.60-0.63

Observation: The obtained cobalt boron acylate has melting point of 94 oC.

B. Comparasion of the properties of the cobalt boron acylate prepared by the known process of example 1 and the cobalt boron acylate prepared in accordance with the present disclosure of example 2:

Table 2 shows the properties including physical appearance, color, melting point, decomposition temperature, and cobalt content of cobalt boron acylate prepared in example 1 and example 2 respectively. The decomposition temperature was determined by Thermogravimetric (TGA) analysis. FIG. 1 shows the difference in the melting point and the decomposition temperature of cobalt boron acylate obtained in examples 1 and 2 respectively.

Table 2: Properties of cobalt boron acylate of example 1 and example 2
Properties Unit Example 1 Example 2
Physical appearance NA Crispy solid Crispy solid
Color NA Purple Purple
Cobalt content % 22-23% 22-23
Melting Point ° C ?125 90-98
Decomposition temperature (By TGA) ° C 348-430 210-320

Observation: Table 1 and FIG. 1 show that the decomposition temperature of cobalt boron acylate obtained in example 1 is in the range of 348-430 °C. The melting point of cobalt boron acylate is more than 125 °C The increase in the decomposition temperature and the melting point of cobalt boron acylate is due to the formation of the polymeric network in the cobalt carboxylate complex. The decomposition temperature and the melting point of cobalt boron acylate prepared in example 2 in accordance with the present disclosure is in the range of 210-320 °C and 90-98 °C respectively. The process of preparing cobalt boron acylate in accordance with the present disclosure limits the formation of the polymeric network in the cobalt-neodeconate complex. The addition of tributyl borate in the initial stage of the process for preparing cobalt boron acylate prevents the formation of a polymeric network in the cobalt-neodeconate complex. This results in low melting point of cobalt boron acylate.

INDUSTRIAL APPLICABILITY
The present disclosure provides an efficient, safe, faster, and highly productive process for the preparation of cobalt boron acylate. The disclosed process provides a solvent-free method to prepare cobalt boron acylate. The disclosed process allows one to avoid the use of solvents like xylene, heptane, and toluene in the reactants which results in ease of handling and transportation. In the disclosed process, tributyl borate is used in an initial stage in the process for preparing cobalt boron acylate. Tributyl borate prevents the formation of a polymeric network in the cobalt-neodeconate complex. The disclosed process does not use any organic solvent in the process for preparing cobalt boron acylate. The disclosed process helps in obtaining cobalt boron acylate with low melting point of 90-98 oC. The low melting point increases the dispersibility of cobalt boron acylate in a rubber compound. The process is completed in a shorter reaction time of 90-100 minutes.