Unlock instant, AI-driven research and patent intelligence for your innovation.

Preparation method of 4-bromo-furan / thiophene-2-methylal

A methylal and furan technology, applied in the field of organic chemical synthesis, can solve the problems of prolonged reaction time, the need for ultra-low temperature, and high raw material cost, and achieves the effects of reduced raw material cost, mild reaction conditions, and simple process operation.

Inactive Publication Date: 2012-10-10
大连联化医药技术有限公司
View PDF1 Cites 0 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The currently known synthetic methods of 4-bromo-furan / thiophene-2-methylal all adopt the tetrahydrofuran solution of 4,5-dibromo-furan / thiophene-2-methylal at -60°C to -50°C. It can be obtained by reacting with 1 equivalent of n-butyllithium at ℃. This method has many defects: (1) The reaction requires ultra-low temperature, the industrial scale-up operation is complicated, and the refrigeration cost is increased; (2) The by-product furan / thiophene-2- The generation of methylal is not easy to control, resulting in a very low yield of the amplification reaction; (3) The raw material 4,5-dibromo-furan / thiophene-2-methylal in the literature needs to be pure, and the cost of raw materials is high

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Preparation method of 4-bromo-furan / thiophene-2-methylal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] A method for preparing 4-bromo-furan / thiophene-2-methyl acetal, taking 4-bromo-furan-2-methyl acetal as an example:

[0019] The first step is the preparation of 4,5-dibromo-furan-2-methyl acetal:

[0020] Add 200.00 g (0.787 mol) 4,5-dibromo-2-furan-formaldehyde, 116.69 g (0.787 mol) triethyl orthoformate into a 1 L four-neck flask equipped with magnetic stirring, thermometer and condenser. 600 mL of absolute ethanol was heated to 75℃~80℃ to react for 2 hours, and the reaction was monitored in the gas phase. After the reaction, 792 mL (0.994 mol / L) of ethanol solution of 4,5-dibromo-furan-2-methyl acetal was obtained, with a yield of 100%;

[0021] The second step is the preparation of 4-bromo-furan-2-methyl acetal:

[0022] Add 131.17 g (1.05 mol) ammonia (28%) and 264 mL (0.262 mol) 4,5-dibromo-furan-2-methyl acetal to a 500 mL four-neck flask equipped with mechanical stirring and thermometer Add 42.71 g (0.655 mol) of zinc powder in 3 batches with the temperature controll...

Embodiment 2

[0024] A method for preparing 4-bromo-furan / thiophene-2-methyl acetal, taking 4-bromo-furan-2-methyl acetal as an example:

[0025] Preparation of the raw material 4,5-dibromo-furan-2-methyal in the first step: same as in Example 1;

[0026] The second step is the preparation of 4-bromo-furan-2-methyl acetal:

[0027] Add 109.34 g (0.874 mol) ammonia (28%) and 220 mL (0.219 mol) 4,5-dibromo-furan-2-methyl acetal into a 500 mL four-neck flask equipped with mechanical stirring and thermometer. Add 35.70 g (0.548 mol) of zinc powder in 3 batches with the temperature controlled below 20°C in ethanol solution (0.994 mol / L), and react at 20°C~25°C for 3 hours. After the gas phase monitoring reaction is over, the reaction solution is filtered with 8.5 g of diatomaceous earth as the main filter aid, and the filter cake is discarded. The filtrate was extracted with 430 mL of dichloromethane (215 mL×2), and the organic layers were combined. The combined organic layer was washed once with 16...

Embodiment 3

[0029] A method for preparing 4-bromo-furan / thiophene-2-methyl acetal, taking 4-bromo-furan-2-methyl acetal as an example:

[0030] Preparation of the raw material 4,5-dibromo-furan-2-methyl formal in the first step:

[0031] Add 150.00 g (0.500 mol) 4,5-dibromo-furan-2-carboxaldehyde, 53.00 g (0.500 mol) trimethyl orthoformate into a 1 L four-neck flask equipped with magnetic stirring, thermometer and condenser. 450 mL of absolute ethanol was heated to 75℃~80℃ to react for 2 hours, and the reaction was monitored in the gas phase. After the reaction is completed, 530 mL (0.943 mol / L) of ethanol solution of 4,5-dibromo-furan-2-methylformal is obtained, with a yield of 100%;

[0032] The second step is the preparation of 4-bromo-furan-2-methyl formal:

[0033] Add 66.00 g (0.528 mol) ammonia (28%) and 140 mL (0.132 mol) of 4,5-dibromo-furan-2-methyl formal into a 500 mL four-neck flask equipped with mechanical stirring and thermometer. Ethanol solution (0.943 mol / L), temperature contr...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The invention belongs to the field of organic chemistry synthesis. A preparation method of 4-bromo-furan / thiophene-2-methylal employs a raw material of 4,5-dibromo-furan / thiophene-2-methylal to conduct a debromination reaction in solvents of ethanol and aqueous ammonia under the effect of zinc powder at 20-25 DEG C. The present invention is innovative in that to avoid debromination reaction of butyl lithium at ultralow temperature used in literature, zinc powder and ammonia are used as a debromination system to produce 4-bromo-furan / thiophene-2-methylal with high yield at room temperature; debromination reagent of n-butyllithium / tetrahydrofuran system is replaced by the cheap zinc powder / ammonia system to greatly reduce the cost of raw materials; besides, the method has mild reaction conditions and is easy for amplification.

Description

Technical field [0001] The invention belongs to the field of organic chemical synthesis. Background technique [0002] The currently known 4-bromo-furan / thiophene-2-methyl acetal synthesis methods all use the tetrahydrofuran solution of 4,5-dibromo-furan / thiophene-2-methyl acetal at -60℃~-50 It can be obtained by reacting with 1 equivalent of n-butyllithium at ℃. This method has many defects: (1) The reaction requires ultra-low temperature, the industrial scale-up operation is cumbersome, and the refrigeration cost is increased; (2) The reaction time is extended by product furan / thiophene-2- The formation of methylal is not easy to control, resulting in a very low yield of the amplification reaction; (3) The raw material 4,5-dibromo-furan / thiophene-2-methylacetal in the literature needs to be pure, and the raw material cost is high. Summary of the invention [0003] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a method for prepa...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
IPC IPC(8): C07D333/28C07D307/56
Inventor 于双
Owner 大连联化医药技术有限公司