63394-09-2Relevant academic research and scientific papers
A trimethoprim intermediate 3, 5 - dibromo - 4 - hydroxybenzaldehyde preparation
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Paragraph 0020; 0021; 0022; 0023; 0024; 0025-0028, (2017/08/25)
The invention provides a preparation method of trimethoprim midbody 3,5-dibromo-4-hydroxy benzaldehyde. The preparation method comprises the following steps of sequentially adding paracresol, ethanoic acid and zinc chloride in a reaction container; uniformly stirring; slowly adding benzyl trimethyl ammonium tribromide after cooling to the temperature of 0 DEG C; reacting for 1-2 hours at the temperature of 10-15 DEG C; heating to the temperature of 90-95 DEG C and reacting for 1.5-3 hours; performing reduced pressure distillation on reaction liquid to recycle acetic acid; adding water in a substrate, stirring, heating and performing backflow hydrolysis for 2-4 hours; cooling to room temperature; and filtering, washing and drying to obtain the 3,5-dibromo-4-hydroxy benzaldehyde. Reaction conditions of the preparation method are gentle, a technology is simple, reaction speed is high, the purity of products is above 98%, yield is above 93%, and BTMABr3 serves as a bromination reagent and replaces bromine with high toxicity. The preparation method has the advantages of safety, zero toxicity and environmental protection.
Efficient and convenient synthesis of 3,4,5-trimethoxybenzaldehyde from p-cresol
Ji, Ya-Fei,Zong, Zhi-Min,Wei, Xian-Yong
, p. 2809 - 2814 (2007/10/03)
With p-cresol as starting material, 3,4,5-trimethoxybenzaldehyde was synthesized in an overall yield of 67.4% via bromination, hydrolysis, methoxylation and methylation.
Synthesis of 3,4,5-Trimethoxybenzaldehyde
Manchand, Percy S.,Belica, Peter S.,Wong, Harry S.
, p. 2659 - 2666 (2007/10/02)
The copper(I)-catalyzed exchange of bromine by methoxide in 5-bromovanillin and in 3,5-dibromo-4-hydroxybenzaldehyde provides an efficient method for preparing 3,5-dimethoxy-4-hydroxybenzaldehyde, from which 3,4,5-trimethoxybenzaldehyde is obtained by methylation with dimethylsulfate.
Solvolytic Elimination and Hydrolysis promoted by an Aromatic Hydroxy Group. Part 1. The Reaction of 2,6-Dibromo-4-dibromomethylphenol and of 2,6-Dibromo-4-bromomethylenecyclohexa-2,5-dienone with Water in 95percent 1,4-Dioxane
Mare, Peter B. D. de la,Newman, Paul A.
, p. 231 - 238 (2007/10/02)
The reaction of 2,6-dibromo-4-dibromomethylphenol with water to give the quinone methide, 2,6-dibromo-4-bromomethylenecyclohexa-2,5-dienone, together with 2,6-dibromo-4-hydroxybenzaldehyde has been studied in 95percent 1,4-dioxane.U.v. spectroscopy has been used to study the kinetic form of the reaction.At very low acidities, rapid conversion into the quinone methide occurs through the aryl oxide ion, and is followed by addition and replacement to give the aldehyde.At acidities greater than 1E-3M, reaction of the un-ionised phenol is dominant and follows a conventional SN1 pathway through a mesomeric carbocationic intermediate.Subsequent loss of a proton from this intermediate to give the quinone methide is competitive with its capture by the solvent (to give in several steps the related aldehyde) and by bromide ion (to give starting material).The mass-law constant for capture of the carbocation by bromide ion is very large (ca. 1E4 in this solvent), so that relatively small concentrations of hydrogen bromide convert the quinone methide back into the dibromomethylphenol by 1,6-addition.Solvent kinetic isotope effects on the individual reaction stages are reported.The rate of solvolysis of the phenol is much greater than would be predicted by the use of conventional linear free-energy parameters.
