Traditional process: p-thiouraylbenzoic acid is generated by reacting aminobenzoic acid with ammonium thiocyanate, and then reacted with methyl iodide to prepare 4-guanidine benzoate hydrochloride. This method requires multiple steps, including the reaction of para-aminobenzoic acid, ammonium thiocyanate, and dilute hydrochloric acid, as well as subsequent processes such as ammonia water treatment and ethanol reflux1.
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Improved process: Ethanol reflow treatment is used to reduce workload and increase yield. In addition, the substitution of ethyl bromide for methyl iodide can reduce production costs and result in a stable product1.
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Other methods: Another method is to react p-aminobenzoic acid with monocyanide to produce a solid product 1.
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Reaction conditions and optimization measures:
Reaction temperature: The optimal reaction temperature is 50°C, and the yield can reach 76.4%. The yield is lower when the temperature is lower than 50°C, and basically unchanged when the temperature is higher than 50°C, but the temperature is too high to increase the occurrence of side reactions1.
Dosage of concentrated hydrochloric acid: When the dosage of p-aminobenzoic acid is 0.35 mol, the optimal dosage of concentrated hydrochloric acid is 30 mL. Splitting the addition of monocyanamide avoids its hydrolysis and improves the control and reproducibility of experimental conditions1.
Properties and applications of 4-guanidinylbenzoate hydrochloride :
Physical properties: 4-guanidine benzoate hydrochloride is a white crystal powder with a melting point of 285 °C, soluble in water, slightly soluble in organic solvents such as ethanol and chloroform 23.
Storage conditions: Should be stored at 2-8°C 2.
Uses: 4-guanidine benzoate hydrochloride has a wide range of applications in the pharmaceutical field, such as as as a pharmaceutical intermediate or pharmaceutical ingredient.
