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A kind of preparation method of methylene blue

A technology of methylene blue and dimethylamino group, applied in the field of preparation of methylene blue, can solve the problems of large environmental protection pressure, high cost of raw materials, low yield and the like, and achieve the effects of less waste, improved efficiency and high product purity

Active Publication Date: 2018-02-13
JIANGSU HERUN PHARMA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0013] Though this route has avoided manganese dioxide and sodium dichromate that pollute the environment seriously, the nitrification reaction produces a large amount of nitrogen oxide waste gas and acid-containing wastewater, which also has a very large impact on the environment; the fourth step yield of the literature is only 30%. raw material cost is high
In the final step, a large amount of ferric chloride is used for oxidation. The iron ion content in the product is high, and multiple washings are required, resulting in a large amount of strongly acidic iron-containing wastewater, which has a great impact on the environment.
[0014] All serious environmental pollution in the reaction process of above-mentioned three kinds of methods, method 1 uses a large amount of hydrogen sulfide and ferric chloride, and yield is on the low side, is not suitable for suitability for industrialized production; Method 2 produces a large amount of manganese dioxide waste residues or dichromic acid Sodium and other wastewater; method 3 nitrification reaction produces reddish-brown nitrogen oxide waste gas and nitrification wastewater is difficult to treat, and oxidation reaction produces a large amount of iron-containing strong acid wastewater
The existing preparation routes are facing great environmental pressure, not an ideal green synthesis process

Method used

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  • A kind of preparation method of methylene blue
  • A kind of preparation method of methylene blue
  • A kind of preparation method of methylene blue

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] Step 1: Preparation of 4,4'-dinitrodiphenylamine (4)

[0046] In a 1L reaction flask, put 138.2g of 4-nitroaniline, 160g of sodium hydroxide and 900g of dimethyl sulfoxide, and add 369g of nitrobenzene dropwise under stirring for about 30 minutes. Then heat up to 60-70°C, and continue to feed oxygen, after 8 hours of reaction, take a sample of HPLC to detect and control 4-nitroaniline≤1.0%; the reaction is finished, the reaction solution is filtered to remove the solid; the filtrate is reduced at 10-20mmHg Remove the solvent and nitrobenzene by pressure distillation, add 200g toluene and 250g water, stir and cool down to crystallize; the solid obtained by filtration is washed twice with 200g water respectively, and dried with hot air circulation at 50°C to obtain 232.5g 4,4'-dinitrobenzene Diphenylamine (4) with a yield of 89%.

[0047] Step 2: Preparation of 4,4'-dimethylaminodiphenylamine (3)

[0048] Put 60.0g of 4,4'-dinitrodiphenylamine (4), 4.0g of 5% palladium ca...

Embodiment 2

[0060] Preparation of 4,4'-dinitrodiphenylamine (4)

[0061] The operation was carried out according to step 1 of Example 1, except that the reaction temperatures were 80-85° C., 70-75° C., 60-65° C. and 50-55° C., and other operating conditions were the same. The yield of 4,4'-dinitrodiphenylamine (4) and the data at different temperatures are shown in Table 1

[0062]

Embodiment 3

[0064] Preparation of 4,4'-dinitrodiphenylamine (4)

[0065] Operate according to step 1 of Example 1, except that the molar ratios of nitrobenzene and p-nitroaniline are respectively 1, 2, 3 and 5, and other operating conditions are the same. The data of different molar ratios and 4,4'-dinitrodiphenylamine (4) yields are shown in Table 2

[0066]

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Abstract

The invention provides a preparation method of methylene blue, and belongs to the technical field of fine chemical synthesis. The preparation method comprises the steps: performing an aromatic nucleophilic substitution reaction of p-nitroaniline and nitrobenzene in the presence of an alkali to obtain 4,4'-dinitrodiphenylamine; then hydrogenating 4,4'-dinitrodiphenylamine in the presence of paraformaldehyde and with palladium on carbon to obtain 4,4'-dimethyl aminodiphenylamine; then performing cyclization of 4,4'-dimethyl aminodiphenylamine in the presence of sulfur and iodine to obtain 4,4'-dimethylamino phenothiazine; next oxidizing 4,4'-dimethylamino phenothiazine with an oxidizing agent to obtain a methylene blue crude product; and finally, refining the methylene blue crude product with purified water to obtain the methylene blue product. The product has high purity, use of toxic and harmful substances is avoided in the process of synthesis, a few of wastes are produced, and the preparation method is quite friendly to the environment and can meet requirements of green and environmental protection.

Description

technical field [0001] The invention belongs to the technical field of fine chemical synthesis, and in particular relates to a preparation method of methylene blue. Background technique [0002] As shown in formula (1), methylene blue has a molecular weight of 319.86, its English name is methylene blue, and its chemical name is 3,7-bis(dimethylamino)phenothiazin-5-ium chloride, which is a phenothiazine salt. [0003] [0004] It was first synthesized in the form of zinc chloride salt by German chemist Heinrich Caro in 1876. Methylene blue can form a non-toxic complex with nitrite or cyanide. It is an antidote and can also be used to treat urinary calculi, obliterative vasculitis, neurodermatitis and oral ulcers. [0005] At present, the preparation of the relevant methylene blue reported in the literature mainly contains the following three methods: [0006] Method 1: J.Am.Chem.Soc., 1940, 62 (1), 204-211 literature report adopts p-amino-N, N-dimethylaniline as starting...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D279/20
CPCC07D279/20
Inventor 张家庆高德华李安排吴正华徐勇史荣先薛峰印星
Owner JIANGSU HERUN PHARMA CO LTD