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Improvement in synthesis of butylated hydroxyanisole from tertiary butyl hydroquinone

A technology of butylated hydroxyanisole and tert-butyl, which is applied in the directions of dehydration of hydroxyl-containing compounds to prepare ether, ether preparation, and ester reaction to prepare ether, etc., and can solve the problem that 3 isomers do not exceed 99%.

Inactive Publication Date: 2009-11-18
凯姆琳精细化学有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Additionally, in all prior art processes, the level of the undesired 2-isomer in the final product was greater than 1%
In none of the prior art methods, the purity of the desired 3-isomer in isolated BHA did not exceed 99%

Method used

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  • Improvement in synthesis of butylated hydroxyanisole from tertiary butyl hydroquinone

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029]166 g of TBHQ suspended in 83 ml of water and 996 ml of hexane were placed in a 5 liter four-necked round bottom flask equipped with a stirrer, thermometer insert and dropping funnel, and stirred at 25-30° C. for 15-20 minutes. 159.32 g of dimethyl sulfate was added thereto and stirred for an additional 15 minutes. A solution of 55.6 g of sodium hydroxide in 111 ml of water was placed in a dropping funnel and added dropwise to the reaction mixture within 1 to 4.5 hours while maintaining the reaction temperature below 45-50°C. After the dropwise addition was complete, the reaction mixture was stirred at 25-30°C for a further 1 hour. The reaction was monitored by thin layer chromatography. The reaction mixture was then cooled to 20-25°C, adjusted to pH 3-4 with 50% sulfuric acid, and stirred at 25-30°C for a further 15-20 minutes. Then settle for 30 minutes.

[0030] The aqueous layer was then separated and discarded. The hexane layer was washed with 250 ml of water, i...

Embodiment 2

[0032] Scale-up test

[0033] Experiment 1 was repeated on a batch scale using 1000 kg or more of TBHQ per batch, with results obtained by varying the relative stoichiometric ratios of TBHQ, DMS, and NaOH to include the following ratios, respectively: (1:1.1:1.33) , (1:1.1:1.46), (1:1.26:1.38), (1:1.1.4:1.46), (1:1.26:1.4), (1:1.1:1.2) and (1:1.03:1.2) . In these ratios (1:1.26:1.38), (1:1.1.4:1.46) are considered close to the ideal situation, the conversion of TBHQ is almost 100% or very close to 100%, and a high yield of BHA is obtained, of which 3 - The purity of the isomers was 99.5% or higher and (1:1.26:1.38) was found to be superior in practice. Of course, any other stoichiometric ratio of TBHQ, DMS and NaOH in which DMS is slightly in excess of TBHQ and NaOH is slightly in excess of DMS can be used, although the above ratios have been identified as preferred ratios, any other stoichiometric ratio It should also be within the scope of the present invention.

Embodiment 3

[0035] BHA in Different Physical Forms

[0036] Large-scale production according to the stoichiometric ratio described in Example 1 resulted in a slurry in which BHA was isolated in crystalline form by cooling the final hexane layer.

[0037] The crystallized solid was isolated by passing the slurry through a Nutsche filter with stirring to separate the crystals.

[0038] The crystalline form gives rise to two other physical forms, a flake form and a compressed form.

[0039] The flake form is formed when the crystals are melted by passing steam through a jacket, and the molten BHA is passed through a flaker machine with cold water circulation. After cooling, the BHA solidifies into flake form during this treatment.

[0040] The crystalline BHA isolated by the Nutsche filter is formed into a compressed form, such as tablets of various sizes, when passed through a tablet press well known in the art, and tablets of various sizes are formed.

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Abstract

An improved process for production and novel physical forms of butylated hydroxyanisole (BHA) is described wherein tertiary butyl hydroquinone (TBHQ) reacts within a range of about 30 to 50 DEG C with stoichiometrically slight excess of dimethyl sulphate and sodium hydroxide, the sodium hydroxide being added stoichiometrially in slight excess of dimethyl sulphate. Major portion of BHA formed in this reaction was recovered in a crystalline form in which 3-t-butyl-4-hydroxyanisole (3 isomer) is at least at about 99% level, usually at about 99.5% or more, and TBHQ at 100 ppm or less. BHA remaining in mother liquor after crystallization was recovered by distillation and had same purity as the crystalline BHA. The crystalline form was prepared as low density as well as high density form and further could be converted into compressed forms including flakes, tablets and the like.

Description

technical field [0001] The present invention relates to a method for the synthesis of butylated hydroxyanisole (BHA) and a new physical form of BHA. Background technique [0002] Butylated hydroxyanisole (BHA), also known as 3-tert-butyl-4-hydroxyanisole, which has two isomers, is widely used as an antioxidant for fats and oils, and is widely used in food, pharmacy, In petroleum and cosmetic industry. Commercially available BHA is in the form of a mixture of predominantly 3-tert-butyl-4-hydroxyanisole (3 isomers) and 2-tert-butyl-4-hydroxyanisole (2 isomers). For its antioxidant properties, the 3-isomer is preferred. [0003] The prior art patent literature teaches us various methods of synthesizing BHA. [0004] U.S. Patent No. 4,538,002 describes a method for the preparation of alkylated hydroxyanisole, which consists of the following steps: dehydrogenating p-isopropylphenol to p-isopropenylphenol, which is then reacted with a methylating agent Generate p-isopropenyl a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C41/09
CPCC07C41/16C07C43/23
Inventor M·N·拉贾德海亚克沙A·K·夏尔马R·S·古普塔A·S·希尔韦卡
Owner 凯姆琳精细化学有限公司
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