Guaiacol vanillin

The preservative BHT has been shown to have adverse effects on the liver and lungs. I70,71 When mixed with another preservative, BHA, the BHA/BHT mixture enhances the lung toxicity. In another study, it was shown that BHA, eugenol methylparaben, vanillin, guaiacol, ferulic acid,... 

Guaiacol has a very characteristic odour and burning taste its medicinal properties are identical with those of creosote. Used in the preparation of vanillin and paparvarin and for denaturing alcohol. 

This is a nifty little way to turn catechol or guaiacol into protocate-chualdehyde or vanillin using what is called the Riemer-Tiemann reaction [137 p824, 138], It is a really ancient reaction and only works on benzene molecules that have an OH group. One needs to use KOH instead of NaOH because it is better at promoting para substitutions (don t ask). And if one is going to make vanillin from guaiacol then there needs to be a little ethanol in the reaction as well. 

When making vanillin from guaiacol the chemist can smell success because the product will have an intense vanilla odor. One can even flavor cookies with the stuff (true ). This Riemer-Tiemann method is also an excellent way to get salicylal-dehyde from phenol in yields of up to 50%. The chemist does everything the same except uses NaOH instead of KOH. 

In 1874, Tiemann and Ha arm ann examined the stmcture of vanillin and reported it to be 3-methoxy-4-hydroxybenzaldehyde. This was not a difficult task because, on treatment with potassium hydroxide, vanillin (1) gave protocatechaic acid [99-50-3] (2), which, in turn, was decarboxylated to catechol [120-80-9] (3) by dry distillation (eq. 1). As both compounds were known at that time, the position of the substituent groups in vanillin was estabHshed. Finally, Reimer synthesized vanillin from guaiacol [90-05-1] and thus proved the identity of its stmcture. In 1894 RhcJ)ne-Poulenc began producing vanillin on an industrial scale. Since then, many other producers have entered into vanillin production, often only to leave it behind. 

The manufacture of vanillin shows the progress made in the chemistry and chemical engineering of the substance. Most commercial vanillin is synthesized from guaiacol the remainder is obtained by processing waste sulfite Hquors. Preparation by oxidation of isoeugenol is of historical interest only. 

In contrast to vanillin from lignin, the principal impurity found in vanillin from guaiacol is 5-methyl vanillin, typically present at levels of about 100 ppm in Rhovanil Extra Pure (Rhc ne-Poulenc), although levels as high as 3000 ppm have been found in samples from other producers. This impurity is completely odorless. 

No residual guaiacol can be found in vanillin produced by the guaiacol process. In contrast to vanillin from lignin, vanillin from guaiacol is extremely consistent in quaUty owing to the consistency of the supply source, and shows no variation in taste, odor, or color. 

Guaiacols. Cresote, obtained from the pyrolysis of beechwood, and its active principles guaiacol [90-05-1] (1) and cresol [93-51-6] (2) have long been used ia expectorant mixtures. The compounds are usually classed as direct-acting or stimulant expectorants, but their mechanisms of action have not been well studied. Cresol is obtained by the Clemmensen reduction of vanillin (3), whereas guaiacol can be prepared by a number of methods including the mercuric oxide oxidation of lignin (qv) (4), the ziac chloride reduction of acetovanillone (5), and the diazotization and hydrolysis of o-anisidine (6). 

Eupe also found that one osmophore can be replaced by another without greatly altering the type of the odour, thus vanilline, p-nitro-guaiacol, and p-cyanoguaiacol all have similar odours but varying in strength. 

Tiemann and Eeimer have prepared vanillin by the action of chloroform on guaiacol in an alkaline medium. The mixture is boiled under a reflux condenser for six hours. A mixture of vanillin and meta-methoxysalicylic aldehyde results. The mixed aldehydes are separated from the reaction mass by means of bisulphite in the usual manner, and the liberated aldehydes are separated in a current of steam. The vanillin is formed according to the following reaction—... 

Another method of obtain"ing vanillin from guaiacol is as follows Formic aldehyde is allowed to react with guaiacol in the presence of phenylhydroxylamine sulphonate —... 

Guyot and Gey have prepared vanUlin by a synthesis depending on the property possessed by compounds containing t-wo carbonyl groups in juxtaposition, of condensing with guaiacol giving products from which it is easy to pass to vanillin. 

Gattefoss6 and Morel La Parfumerie Moderne, 1919, 114) describe a method for the production of vanillin by reducing nitrobenzene-sul-phonic acid with iron filings and hydrochloric acid in the presence of guaiacol and formic aldehyde. The first-named body is reduced to phenyl-hydroxylamine-sulphonic acid, which reacts with the guaiacol as follows —... 

Chlorinated phenolic compounds. Chlorinated phenolic compounds include phenols, guaiacols, catechols, and vanillins substituted with from one to five chlorine atoms per molecule. Typically, bleaching processes that result in the formation of 2,3,7,8-TCDD and... 

Guaiacol, by the action of chloroform and alkali, gives vanillin in poor yield along with the o-aldehyde. 

C9H10O3, Mr 166.18, mp ll-li°C, does not occur in nature. Its odor resembles that of vanillin but is approximately three times as strong. Ethylvanillin can be prepared by method 2 as described for vanillin, using guethol instead of guaiacol as the starting material. 

For example, vanillin can be obtained via at least five different ways (i) by isolation from the orchid (Vanilla planifolia), which is a very expensive method (ii) by tissue culture followed by extraction (iii) by microbial transformation of eugenol, the main compound of clove (iv) from lignine by synthesis, and (v) from guaiacol, a natural aroma compound, with comparable molecular structure. Only the vanillin obtained via the first three methods is natural. The other routes afford a nature-identical vanillin. 

Preparation from Waste Sulfite Liquors. The starting material for vanillin production can also be the lignin present in sulfite wastes from the cellulose industry. The concentrated mother liquors are treated with alkali at elevated temperature and pressure in the presence of oxidants. The vanillin formed is separated from the by-products, particularly ace-tovanillone. 4-hydroxy-3-methoxyacetophenone, by extraction, distillation, and crystallization. In contrast to vanillin from lignin, the principal impurity found in vanillin from guaiacol is 5-methyl vanillin, typically present at levels of about 100 ppm, although levels as high as 3000 ppm have been found. This impurity is completely odorless. 

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