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A technology of quality and nitrosalicylaldehyde, applied in chemical instruments and methods, preparation of organic compounds, organic chemistry, etc., can solve problems such as pollution and high cost, and achieve simple operation and post-processing, short reaction time and low cost Effect
Active Publication Date: 2020-08-14
CHANGZHOU VOCATIONAL INST OF ENG
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Problems solved by technology
However, halogenated aromatic hydrocarbons are environmentally harmful substances, and there are also problems such as high cost or serious pollution in the later reduction reaction.
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Embodiment 1
[0038] Add p-nitrophenol (14g, 0.1mol), p-toluenesulfonic acid (26g, 0.15mol) and absolute ethanol (150ml) in sequence in a four-necked reaction flask, slowly raise the temperature to 65°C, and add hexamethylene in 3 batches Tetramine (21g, 0.15mol) was reacted at 78°C for 2h. After the reaction was completed, the heating was stopped, and ice water was poured into the reaction solution, and it was raised to room temperature under stirring. A light yellow solid was precipitated, filtered, washed, and dried to obtain Pale yellow solid 5-nitrosalicylaldehyde (15.5g, 86.5%), purity 96.91%, 1 HNMR schematic diagram as figure 1 shown.
Embodiment 2
[0040] Add p-nitrophenol (14g, 0.1mol), p-toluenesulfonic acid (34.7g, 0.2mol) and absolute ethanol (150ml) in sequence in a four-necked reaction flask, slowly raise the temperature to 78°C, and add hexaethylene in 3 batches Methyltetramine (56g, 0.4mol), reacted at 78°C for 2h. After the reaction was completed, stop heating, pour ice water into the reaction solution, and raise it to room temperature under stirring. A light yellow solid precipitated, filtered, washed, and dried. 5-nitrosalicylaldehyde (16.7 g, 89.4%) was obtained as a pale yellow solid with a purity of 95.42%.
[0041] (2) Preparation of 5-nitrosalicylic acid
Embodiment 3
[0043] Add 5-nitrosalicylaldehyde (16.7g, 0.1mol), potassium tert-butoxide (22.4g, 0.2mol), copper bromide (1.1g, 5mmol) and acetonitrile (250ml) successively in the reaction flask, stir Add 70% tert-butyl hydroperoxide (26g, 0.1mol) dropwise and react at 80°C for 5h. After the reaction is over, concentrate under reduced pressure to remove the solvent, pour cold water into the residue, stir, and filter with suction. The filtrate is washed with hydrochloric acid Adjust the pH to 2-3, filter with suction, and dry to obtain 5-nitrosalicylic acid (13.6 g, 89.34%) as a pale yellow solid with a purity of 97.31%. 1 HNMR schematic diagram as figure 2 shown.
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Abstract
A method for synthesizing mesalazine is disclosed. The method comprises the following steps: 1) adding p-nitrophenol, p-toluenesulfonic acid, absolute ethyl alcohol and hexamethylenetetramine, stopping heating after the reaction is finished, heating to room temperature while stirring with ice water, separating out solids, filtering, washing and drying to obtain 5-nitrosalicylaldehyde; 2) adding the 5-nitrosalicylaldehyde, potassium tert-butoxide, copper salt and acetonitrile, adding tert-butyl hydroperoxide while stirring, after the reaction is finished, performing vacuum concentration to remove the solvent, pouring cold water into residues, stirring, performing suction filtration, adjusting the pH value of the filtrate with hydrochloric acid, performing suction filtration, and drying to obtain 5-nitrosalicylic acid; and 3) adding stannous chloride dihydrate, concentrated hydrochloric acid, the 5-nitrosalicylic acid and ethanol, carrying out vacuum concentration after the reaction is finished, dissolving residues in water, adjusting the pH value with a concentrated hydrochloric acid solution, standing for crystallization, carrying out suction filtration, washing filter cake with water, and drying to obtain mesalazine. No isomer is generated, and the yield is high; the method does not need high-temperature and high-pressure conditions; the reaction cost is low; and raw materialsand auxiliary materials with high toxicity and heavy environmental pollution are not used.
Description
technical field [0001] The invention belongs to the field of chemical reagent preparation and relates to a method for synthesizing mesalazine. Background technique [0002] Mesalamine, also known as masalazine, chemical name 5-amino-2-hydroxybenzoic acid (5-ASA), 5-aminosalicylic acid, is a drug for the treatment of ulcerative colitis. Compared with other similar drugs, mesalamine has the characteristics of colon-specific release, low toxicity, low adverse reactions and strong tolerance. [0003] The preparation method of mesalamine mainly contains four kinds at present. [0004] 1. Salicylic acid nitration reduction method. This method uses salicylic acid as raw material, synthesizes 5-nitrosalicylic acid through nitration reaction, and then reduces it to obtain 5-aminosalicylic acid. Although the process is mature, due to the positioning effect of the hydroxyl and carboxyl groups in the intermediate nitrobenzene molecule, the selectivity of the nitration reaction is poo...
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