香兰素的合成工艺进展

本文介绍了香兰素的合成方法及评述。     

香兰素的合成及其应用

本文介绍了香兰素的合成方法及其在精细化工领域中的应用。     

香兰素及其合成方法

本文介绍了香兰素的物理，化学性质，用途及合成方法，并对各种合成方法进行了比较。     

香兰素的合成及应用

综述了一种广谱香料香兰素的合成方法和应用进展。指出以对羟基苯甲醛为原料合成香兰素具有广阔的开发前景。     

合成香兰素新工艺的研究

本文介绍了以对羟基苯甲醛为原料合成香兰素的工艺路线及其有关参数，其产品达到了香兰素的质量指标，收率可达８０％。     

合成香兰素新工艺的研究

香兰素是一种广泛地用于食品工业的香料，一般来说用愈创木酚和木质素生产香兰素有种种缺陷，诸如产率低、废物处理等问题。     

香兰素的合成方法评述

叙述了香兰素的特性，用途和主要的合成方法，并对各种合成方法进行了简要的评述。     

香兰素的合成工艺进展

本文叙述了香兰素的现状及应用领域,综述了国内外香兰素的合成方法及技术进展。     

乙基香兰素的合成

乙基香兰素(乙基香草醛,3-乙氧基-4-羟基苯甲醛)是一种合成香料,具有类似于香兰素(香草醛)结构的芳香化合物,国外商品名称有 Vairone、Erhavan(Mosanto Co.)及 Vanaldol(Fries Bros)等。乙基香兰香比同量的香兰素香味强3～4.5倍,可以代替香兰素调配食用香精,广泛用于糖果(65ppm)、巧克力(250ppm)、调味品(140～200ppm)、     

从对甲酚合成香兰素

在碱性条件下,以氧气作为氧化剂,氯化铜和氯化钴作为催化剂,甲醇作为溶剂进行了甲酚液相氧化,高选择性得对羟基苯甲醛,再通过在氯仿中进行单溴化反应,在甲醇中以氯化亚铜和ＤＭＦ催化进行甲氧基化反应得以香兰素,这种高效制备方法总收率达６２．４％。     

乙醛酸法合成香兰素的研究

对愈创木酚与乙醛酸缩合-氧化法制备香兰素工艺进行了研究,对缩合反应中的反应温度、反应液的pH值、加料方式、原料配比以及氧化反应中的催化剂、介质的pH值、反应时间、温度等反应条件进行了优化,使香兰素总收率达到75％,产品纯度＞99％.该工艺国内领先,接近国际先进水平,为实现产业化奠定了基础.     

Modeling of vanillin production in a structured bubble column reactor

Vanillin is an important flavour. Semi-synthetic vanillin can be produced by the oxidation of lignin. Experimental studies leading to vanillin production in a batch reactor and a structured bubble column reactor (SBCR) lead us to the conclusion that the SBCR could have non-idealities such as dispersion. The radial and axial liquid-phase dispersion within the packed criss-crossing sandwich structures of Mellapak-750Y had been studied. A 2D model accounting for axial and radial velocities and dispersion was formulated and solved. The model predictions were compared with that of an experimental residence time distribution curve. The axial dispersion coefficient of the liquid phase is of the same order of magnitude as the radial dispersion coefficient. The reaction kinetics available in literature is adopted for the present study. Model for the SBCR was formulated and simulated using commercial modeling software. Simulation experiments were conducted in a SBCR. The effect of the following parameters on the yield of vanillin is studied: lignin concentration, lignin molecular weight, oxygen partial pressure and reaction temperature. It can be said that lignin molecular weight is a crucial parameter in vanillin production.     

Synthesis of vanillin and 4-hydroxybenzaldehyde by a reaction scheme involving condensation of phenols with glyoxylic acid

Synthesis of vanillin and 4-hydroxybenzaldehyde from guaiacol and phenol, respectively, was investigated. The condensation of guaiacol and phenol with glyoxylic acid in an aqueous alkaline medium resulted in the formation of 3-methoxy-4-hydroxymandelic and 4-hydroxymandelic acid respectively. A process version for the condensation of the phenol with glyoxylic acid, wherein it was found advisable to add an aqueous solution of glyoxylic acid and part of alkali to a batch of the phenol in aqueous alkali, was found to give 77% yield of the mandelic acid based on glyoxylic acid. The oxidation of the mandelic acid could be more suitably carried out at 95°C using 0.51 mol of copper (II) hydroxide for every mole of the mandelic acid in a process where air is simultaneously passed. Taking 3-methoxy-4-hydroxymandelic acid as an example, 88% conversion to vanillin could be obtained. The reaction was found to be second order with respect to the mandelic acid.     

A comparative photocatalytic activity of titanium dioxide and zinc oxide by investigating the degradation of vanillin

The photocatalytic degradation of an organic pollutant such as vanillin has been investigated in aqueous suspensions of titanium dioxide and zinc oxide by monitoring the change in substrate concentration employing UV spectroscopic analysis and decrease in Total Organic Carbon (TOC) content as a function of irradiation time under a variety of conditions. The degradation of the model compound was studied under different conditions such as pH, catalyst concentration, substrate concentration and in the presence of an electron acceptor such as hydrogen peroxide besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient as compared with other photocatalysts, Hombikat UV100 and ZnO.     

5-氯邻香兰素的合成

以邻香兰素为原料,分别采用氯气和磺酰氯作氯化剂合成5-氯邻香兰素,并对两种氯化方法进行了比较。结果表明,以氯气作氯化剂产率高,副产物少,效果更好。考察了以氯气作氯化剂时原料摩尔比、反应时间和反应温度等因素对反应的影响,确定了较优合成条件：原料摩尔比1︰1.5,反应时间20min,反应温度50℃,产率可达80.7%。     

乙醛酸法合成香兰素缩合反应的催化研究

以愈创木酚和乙醛酸为原料，通过催化缩合反应合成香兰素的中间体3-甲氧基-4-羟基扁桃酸（MHMA）。研究了不同种类催化剂对愈创木酚-乙醛酸法合成香兰素的缩舍反应的影响。结果表明：1^#催化剂对愈创木酚和乙醛酸缩合反应的活性较高，乙醛酸的转化率可达95％以上，3-甲氧基-4-羟基扁桃酸的选择性达85％。     

Lignin oxidation to generate vanillin: An integrated learning project for chemical engineering students

This paper presents an integrated learning project of 8 months duration, suitable for chemical engineering students entering their First year of major concentration. This project prepares students for a career in chemical engineering and aids their performance in multi-task problem solving using a teamwork approach. In the process, they develop essential competences, such as communication, perseverance, time management, and autonomy.     

香兰素1,2-辛二醇缩醛的合成

以香兰素和1,2-辛二醇为原料,磷酸为催化剂,正己烷为带水剂合成香兰素1,2-辛二醇缩醛。研究了醛醇摩尔比、催化剂种类及用量、带水剂种类、反应时间等因素对缩醛收率的影响。合成较佳工艺条件为:n(香兰素)∶n(1,2-辛二醇)=1∶1.5,85%磷酸用量为香兰素的3.29%,带水剂正己烷体积与香兰素质量比为2.63 m L/g,78℃左右回流8 h,后处理得淡黄色黏稠状液体,为香兰素1,2-辛二醇缩醛。反应收率最高达83.4%,反应重现性较好,产物纯度为95.2%。     

从香兰素合成3,4,5-三甲氧基苯甲醛

以香兰素为原料,经溴化、甲氧基化、甲基化３步反应合成药物中间体３,４,５－三甲氧基苯甲醛（ＴＭＢ）,总收率达７５．７％。溴化采用氢溴酸与过氧化氢作为溴化试剂,甲氧基化以氯化亚铜、二氧化碳协同催化,丁香醛酚钠盐不需酸化直接进行甲基化反应     

香兰素1,2-辛二醇缩醛的合成

以香兰素和1,2-辛二醇为原料,磷酸为催化剂,正己烷为带水剂合成香兰素1,2-辛二醇缩醛。研究了醛醇摩尔比、催化剂种类及用量、带水剂种类、反应时间等因素对缩醛收率的影响。合成较佳工艺条件为:n(香兰素)∶n(1,2-辛二醇)=1∶1.5,85%磷酸用量为香兰素的3.29%,带水剂正己烷体积与香兰素质量比为2.63 m L/g,78℃左右回流8 h,后处理得淡黄色黏稠状液体,为香兰素1,2-辛二醇缩醛。反应收率最高达83.4%,反应重现性较好,产物纯度为95.2%。