1. The method for recovering trans-p-aminocyclohexanol from low-concentration waste liquid is characterized by comprising the following steps of:

s1, adjusting the pH of the waste liquid to 9-11, adding benzaldehyde, stirring and reacting for 1-3h, filtering and drying to obtain trans-4- (benzylidene-amino) -cyclohexanol; the waste liquid contains trans-p-aminocyclohexanol;

s2, adding trans-4- (benzylidene-amino) -cyclohexanol into sulfuric acid solution, adjusting pH to 1-4, stirring for reaction for 1-3h, standing for layering to separate out lower layer solution, and obtaining trans-p-aminocyclohexanol sulfate aqueous solution;

s3, adding a decolorizing agent into the trans-p-aminocyclohexanol sulfate aqueous solution, stirring, decolorizing and filtering, adjusting the alkali content of the filtrate to 10-25%, stirring for reacting for 0.2-1h, standing, layering and separating out a trans-p-aminocyclohexanol oil layer, adding an extracting agent into the trans-p-aminocyclohexanol oil layer, extracting, concentrating and refining to obtain the trans-p-aminocyclohexanol.

2. The method of claim 1, wherein: the concentration of trans-p-aminocyclohexanol in the waste liquid is 0.5-5%.

3. The method of claim 1, wherein the following reaction occurs in S1:

4. the method of claim 1, wherein the following reaction occurs in S2:

5. the method of claim 4, wherein: the benzaldehyde can be recycled in S1.

6. The method of claim 1, wherein: in the S3, sodium hydroxide is added into the filtrate to adjust the alkali content of the filtrate to 10-25%.

7. The method of claim 6, wherein the following reaction occurs in S3:

8. the method of claim 1, wherein: in the S2, the concentration of the sulfuric acid solution is 10-50%.

9. The method of claim 1, wherein: in S3, the decoloring agent is activated carbon.

10. The method of claim 1, wherein: in the S3, the extracting agent is one of toluene, xylene, chloroform and dichloroethane.

Background

Trans-p-aminocyclohexanol, white or off-white crystalline powder, darkened in color under light or long-term storage, has strong water absorption, can be dissolved in organic solvents such as chloroform and the like, is one of common organic synthetic raw materials, and has a molecular formula of C₆H₁₃NO。

The trans-p-aminocyclohexanol is an important intermediate for synthesizing ambroxol hydrochloride, and the ambroxol hydrochloride is an important medicine and can promote the discharge of viscous secretion in respiratory tracts and reduce the retention of mucus, so that the trans-p-aminocyclohexanol has a remarkable effect of promoting sputum excretion and is suitable for acute and chronic respiratory diseases with abnormal sputum excretion and poor sputum excretion function. Therefore, ambroxol hydrochloride is commonly used for treating acute and chronic respiratory diseases, bronchial secretion abnormality and the like.

When the trans-p-aminocyclohexanol is used for synthesizing ambroxol hydrochloride, the main raw material 2-amino-3, 5-dibromobenzaldehyde and excessive trans-p-aminocyclohexanol are heated and condensed until the 2-amino-3, 5-dibromobenzaldehyde reacts, then sodium borohydride or potassium borohydride is used for reducing in methanol or ethanol, and ambroxol hydrochloride is salified by hydrochloric acid to obtain the ambroxol hydrochloride.

However, when ambroxol hydrochloride is synthesized, in order to promote the forward progress of the synthesis reaction, the trans-p-aminocyclohexanol is excessively added, so that the synthesis waste liquid contains the trans-p-aminocyclohexanol remained in the reaction, and the waste of raw materials is caused.

Disclosure of Invention

In order to recover trans-p-aminocyclohexanol from reaction waste liquid for synthesizing ambroxol hydrochloride, the application provides a method for recovering trans-p-aminocyclohexanol from low-concentration waste liquid.

The method for recovering trans-p-aminocyclohexanol from low-concentration waste liquid adopts the following technical scheme:

a method for recovering trans-p-aminocyclohexanol from low concentration waste liquor, the method comprising the steps of:

s1, adjusting the pH of the waste liquid to 9-11, adding benzaldehyde, stirring and reacting for 1-3h, filtering and drying to obtain trans-4- (benzylidene-amino) -cyclohexanol;

s2, adding trans-4- (benzylidene-amino) -cyclohexanol into sulfuric acid solution, adjusting pH to 1-4, stirring for reaction for 1-3h, standing for layering to separate out lower layer solution, and obtaining trans-p-aminocyclohexanol sulfate aqueous solution;

s3, adding a decolorizing agent into the trans-p-aminocyclohexanol sulfate aqueous solution, stirring, decolorizing and filtering, adjusting the alkali content of the filtrate to 10-25%, stirring for reacting for 0.2-1h, standing, layering and separating out a trans-p-aminocyclohexanol oil layer, adding an extracting agent into the trans-p-aminocyclohexanol oil layer, extracting, concentrating and refining to obtain the trans-p-aminocyclohexanol.

By adopting the technical scheme, in S1, benzaldehyde is added into the waste liquid, and the benzaldehyde and trans-p-aminobenzaldehyde undergo a condensation reaction to obtain trans-4- (benzylidene-amino) -cyclohexanol in a solid state; in S2, adding trans-4- (benzylidene-amino) -cyclohexanol to a sulfuric acid solution, wherein after dissolution, the C ═ N double bond in the trans-4- (benzylidene-amino) -cyclohexanol is cleaved to obtain trans-p-aminocyclohexanol, and the sulfuric acid solution functions as a catalytic hydrolysis agent, and the trans-p-aminocyclohexanol and sulfuric acid form an aqueous trans-p-aminocyclohexanol sulfate solution; in S3, the decolored sulfuric acid solution of trans-p-aminocyclohexanol is made alkaline to remove sulfuric acid, and the trans-p-aminocyclohexanol is extracted with an extractant and concentrated and purified to obtain trans-p-aminocyclohexanol.

Preferably, the concentration of trans-p-aminocyclohexanol in the waste liquid is 0.5-5%. Experiments designed by the invention prove that the method can obtain the trans-p-aminocyclohexanol from the low-concentration trans-p-aminocyclohexanol solution, and provides a good theoretical basis for recovering the low-concentration trans-p-aminocyclohexanol in the ambroxol hydrochloride synthetic waste liquid.

Preferably, the following reaction occurs in S1:

preferably, the following reaction occurs in S2:

preferably, the benzaldehyde can be recycled in S1.

Preferably, in S3, sodium hydroxide is added to the filtrate to adjust the pH of the filtrate to be equal to or more than 10.

Preferably, the following reaction occurs in S3:

preferably, in the S2, the concentration of the sulfuric acid solution is 10-50%.

Preferably, in S3, the decolorizing agent is activated carbon.

Preferably, in the S3, the extractant is toluene.

In summary, the present application has the following beneficial effects: in the process of synthesizing the ambroxol hydrochloride bulk drug, the excessive trans-p-aminocyclohexanol is discharged by washing, so that the environmental protection treatment pressure (high COD and ammonia nitrogen) and the cost are increased, and the production raw materials are wasted. The invention researches a method for recovering trans-p-aminocyclohexanol from 0.5-5% of trans-p-aminocyclohexanol aqueous solution, synthesizes a new trans-4- (benzylidene-amino) -cyclohexanol product, and obtains the trans-p-aminocyclohexanol with the content of 99% for recycling by a method of hydrolyzing a cheap raw material by acid and separating out a solvent by alkali, thereby saving the raw material cost and reducing the environmental pollution, about 60 kg of trans-aminocyclohexanol can be recovered from 1000 kg of ambroxol hydrochloride raw material, the cost is saved by about 20000 yuan, and the annual recovery economic value of 100 tons of ambroxol hydrochloride raw material pharmaceutical factories is very considerable.

Detailed Description

The present application will be described in further detail with reference to examples.

Examples

Example 1

100g of a 0.5% trans-p-aminocyclohexanol standard solution was prepared as a low-concentration waste liquid containing trans-p-aminocyclohexanol in example 1, which contained 0.00434mol of trans-p-aminocyclohexanol.

In this example 1, the conversion of trans-p-aminocyclohexanol to trans-4- (benzylidene-amino) -cyclohexanol comprises the following steps:

adding 100g of 0.5% trans-p-aminocyclohexanol standard solution into a reaction bottle, adding a sodium hydroxide solution to adjust the pH to 9-11, adding 0.00443mol of benzaldehyde, stirring and reacting at normal temperature for 1-3h, filtering and drying to obtain 0.00412mol of trans-4- (benzylidene-amino) -cyclohexanol, wherein the calculated yield is 95%.

Example 2

100g of a 1% by mass trans-p-aminocyclohexanol standard solution was prepared as a low-concentration waste liquid containing trans-p-aminocyclohexanol in example 2, and 0.00868mol of trans-p-aminocyclohexanol was contained therein.

In this example 2, the conversion of trans-p-aminocyclohexanol to trans-4- (benzylidene-amino) -cyclohexanol comprises the following steps:

adding 100g of 1% trans-p-aminocyclohexanol standard solution into a reaction bottle, adding a sodium hydroxide solution to adjust the pH to 9-11, adding 0.00886mol of benzaldehyde, stirring at normal temperature to react for 1-3h, filtering and drying to obtain 0.00833mol of trans-4- (benzylidene-amino) -cyclohexanol, wherein the calculated yield is 96%.

Example 3

100g of a 3% by mass trans-p-aminocyclohexanol standard solution was prepared as a low-concentration waste liquid containing trans-p-aminocyclohexanol in example 3, and 0.02604mol of trans-p-aminocyclohexanol was contained therein.

In this example 2, the conversion of trans-p-aminocyclohexanol to trans-4- (benzylidene-amino) -cyclohexanol comprises the following steps:

adding 100g of 3% trans-p-aminocyclohexanol standard solution into a reaction bottle, adding a sodium hydroxide solution to adjust the pH to 9-11, adding 0.02658mol of benzaldehyde, stirring at normal temperature to react for 1-3h, filtering and drying to obtain 0.02553mol of trans-4- (benzylidene-amino) -cyclohexanol, wherein the calculated yield is 98%.

Example 4

100g of a 5% by mass trans-p-aminocyclohexanol standard solution was prepared as a low-concentration waste liquid containing trans-p-aminocyclohexanol in example 4, which contained 0.04341mol of trans-p-aminocyclohexanol.

In example 4, the conversion of trans-p-aminocyclohexanol to trans-4- (benzylidene-amino) -cyclohexanol comprises the following steps:

adding 100g of 5% trans-p-aminocyclohexanol standard solution into a reaction bottle, adding a sodium hydroxide solution to adjust the pH to 9-11, adding 0.0443mol of benzaldehyde, stirring and reacting at normal temperature for 1-3h, filtering and drying to obtain 0.04298mol of trans-4- (benzylidene-amino) -cyclohexanol, wherein the calculated yield is 99%.

Example 5

The conversion of trans-4- (benzylidene-amino) -cyclohexanol of examples 1-4 was carried out several times and the resulting trans-4- (benzylidene-amino) -cyclohexanol was mixed.

100g of a 10% by mass aqueous sulfuric acid solution containing 0.10196mol of sulfuric acid was prepared.

In this example 5, the conversion of trans-4- (benzylidene-amino) -cyclohexanol to an aqueous trans-p-aminocyclohexanol sulfate solution comprises the following steps:

100g of 10% sulfuric acid aqueous solution is added into a reaction bottle, 0.20169mol of trans-4- (benzylidene-amino) -cyclohexanol is added, the mixture is stirred and reacted for 1-3h at normal temperature in the environment with pH being 1-4, the reaction solution is transferred into a separating funnel, the mixture is kept stand and layered for 15-60min, and then separation is carried out, so that 116.2g of trans-p-aminocyclohexanol sulfate solution at the lower layer and 0.2374mol of benzaldehyde oil layer at the upper layer are obtained, wherein the benzaldehyde oil layer can be recycled in examples 1-4.

Example 6

The conversion of trans-4- (benzylidene-amino) -cyclohexanol of examples 1-4 was carried out several times and the resulting trans-4- (benzylidene-amino) -cyclohexanol was mixed.

100g of a 30% by mass aqueous sulfuric acid solution containing 0.30587mol of sulfuric acid was prepared.

In this example 6, the conversion of trans-4- (benzylidene-amino) -cyclohexanol to an aqueous trans-p-aminocyclohexanol sulfate solution comprises the following steps:

100g of 30% sulfuric acid aqueous solution is added into a reaction bottle, 0.60504mol of trans-4- (benzylidene-amino) -cyclohexanol is added, the mixture is stirred and reacted for 1-3h at normal temperature in the environment with pH being 1-4, the reaction solution is transferred into a separating funnel, the mixture is kept stand and layered for 15-60min, and then separation is carried out, 146.1g of trans-p-aminocyclohexanol sulfate solution at the lower layer and 0.7274mol of benzaldehyde oil layer at the upper layer are obtained, wherein the benzaldehyde oil layer can be recycled in examples 1-4.

Example 7

The conversion of trans-4- (benzylidene-amino) -cyclohexanol of examples 1-4 was carried out several times and the resulting trans-4- (benzylidene-amino) -cyclohexanol was mixed.

100g of a 50% by mass aqueous sulfuric acid solution containing 0.50979mol of sulfuric acid was prepared.

In this example 7, the conversion of trans-4- (benzylidene-amino) -cyclohexanol to an aqueous trans-p-aminocyclohexanol sulfate solution was carried out by the following steps:

adding 100g of 50% sulfuric acid aqueous solution into a reaction bottle, adding 1.00846mol of trans-4- (benzylidene-amino) -cyclohexanol, stirring and reacting at normal temperature in an environment with the pH value of 1-4 for 1-3h, transferring the reaction liquid into a separating funnel, standing and layering for 15-60min, and separating to obtain 218.2g of trans-p-aminocyclohexanol sulfate solution as a lower layer and 0.8229mol of benzaldehyde oil layer as an upper layer, wherein the benzaldehyde oil layer can be recycled in examples 1-4.

Example 8

The procedure for recovering trans-p-aminocyclohexanol in example 8 was carried out by weighing 100g of the trans-p-aminocyclohexanol sulfate solution obtained in example 5.

In this example 8, the recovery of trans-p-aminocyclohexanol included the following steps:

100g of trans-p-aminocyclohexanol sulfate solution was put into a reaction flask, activated carbon was added at normal temperature, the mixture was stirred and decolored for 30 to 60 minutes, and then filtered, 0.75mol of sodium hydroxide was added to the filtrate under stirring, the mixture was stirred and reacted at 50 to 70 ℃ for 20 minutes, and then the mixture was allowed to stand for 30 to 60 minutes to separate layers, and a trans-p-aminocyclohexanol oil layer was separated, dehydrated and extracted with toluene, and concentrated and purified to obtain 16.2g (0.1407mol) of trans-p-aminocyclohexanol, and the calculated yield was 0.1407 ÷ (0.20169 × 100 ÷ 116.2) × 100%: 81%.

Example 9

The procedure for recovering trans-p-aminocyclohexanol in example 9 was carried out by weighing 100g of the trans-p-aminocyclohexanol sulfate solution obtained in example 6.

100g of trans-p-aminocyclohexanol sulfate solution was put into a reaction flask, activated carbon was added at normal temperature, the mixture was stirred and decolored for 30 to 60 minutes, and then filtered, 1.25mol of sodium hydroxide was added to the filtrate under stirring, the mixture was stirred and reacted at 50 to 70 ℃ for 20 minutes, and then the mixture was allowed to stand for 30 to 60 minutes to separate layers, and a trans-p-aminocyclohexanol oil layer was separated, dehydrated and extracted with toluene, and concentrated and purified to obtain 40.2g (0.3490mol) of trans-p-aminocyclohexanol, and the calculated yield was 0.3490 ÷ (0.60508 × 100 ÷ 146.1) × 100%, (84.26%).

Example 10

The procedure for recovering trans-p-aminocyclohexanol in example 10 was carried out by weighing 100g of the trans-p-aminocyclohexanol sulfate solution obtained in example 7.

100g of trans-p-aminocyclohexanol sulfate solution was put into a reaction flask, activated carbon was added at normal temperature, the mixture was stirred and decolored for 30 to 60 minutes, and then filtered, 1.75mol of sodium hydroxide was added to the filtrate under stirring, the mixture was stirred and reacted at 50 to 70 ℃ for 20 minutes, and then the mixture was allowed to stand for 30 to 60 minutes to separate layers, and a trans-p-aminocyclohexanol oil layer was separated, dehydrated and extracted with toluene, and concentrated and purified to obtain 45.1g (0.3915mol) of trans-p-aminocyclohexanol, and the calculated yield was 0.3915 ÷ (1.0084 × 100 ÷ 218.2) × 100%: 84.7%.

Examples 1-4, the higher the concentration of trans-p-aminocyclohexanol, the higher the yield of trans-p-aminocyclohexanol when the conversion was carried out on the various concentrations of the standard trans-p-aminocyclohexanol, and in example 1, the yield of trans-p-aminocyclohexanol was 95% when the content of trans-p-aminocyclohexanol was 0.5%, whereas in example 4, the yield of trans-p-aminocyclohexanol was 99% when the content of trans-p-aminocyclohexanol was 5%.

Examples 5-7, the trans-4- (benzylidene-amino) -cyclohexanol obtained in examples 1-4 was converted into trans-p-aminocyclohexanol sulfate solution, in example 5 trans-4- (benzylidene-amino) -cyclohexanol was added to sulfuric acid solution, and the molar ratio of trans-4- (benzylidene-amino) -cyclohexanol to sulfuric acid was 0.20169: 0.10196, i.e. the molar amount of sulphuric acid is slightly more than half the molar amount of trans-4- (benzylidene-amino) -cyclohexanol, promoting the conversion of trans-4- (benzylidene-amino) -cyclohexanol.

Example 8 the trans-p-aminocyclohexanol sulfate solution obtained by conversion in example 5 was converted into trans-p-aminocyclohexanol, sodium hydroxide was added to the sulfate solution, and acid-base neutralization reaction was carried out between sodium hydroxide and sulfuric acid to obtain trans-p-aminocyclohexanol, and after standing, the trans-p-aminocyclohexanol oil layer was separated from the solution layer, and the trans-p-aminocyclohexanol oil layer was separated, and purified by concentration to obtain a pure product with a yield of 81%.

Similarly, example 9 converts the trans-p-aminocyclohexanol sulfate solution of example 5 to 84.26% yield; the yield in example 10 reached 84.7%.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.