Aldehydes vanillin

Other commonly occurring chemical groups ia essential oils iaclude aromatics such as P-phenethyl alcohol, eugenol, vanillin, ben2aldehyde, cinnamaldehyde, etc heterocycHcs such as iadole (qv), pyra2iaes, thia2oles, etc hydrocarbons (Liaear, branched, saturated, or unsaturated) oxygenated compounds such as alcohols, acids, aldehydes, ketones, ethers and macrocyclic compounds such as the macrocyclic musks, which can be both saturated and unsaturated. 

Vanillin is a compound that possesses both a phenoHc and an aldehydic group. It is capable of undergoing a number of different types of chemical reactions. Addition reactions are possible owing to the reactivity of the aromatic nucleus. 

Because vanillin is a phenol aldehyde, it is stable to autooxidation and does not undergo the Cannizzarro reaction. Numerous derivatives can be prepared by etherification or esterification of the hydroxy group and by aldol condensation at the aldehyde group. AH three functional groups in vanillin are... 

Vanillin, being an aldehyde, is able to form acetals and hemiacetals. Therefore, in flavor formulations using high concentrations of vanillin in conjunction with carriers such as propylene glycol, a glc analysis often shows a reduced vanillin peak after storage of the compounded flavor, and the presence of new peaks indicating acetal formation. Addition of about 0.5% of water to the formula reverses the reaction, ie, there is a reduction of acetal, and the reappearance of vanillin peaks. 

It has been shown that aromatic aldehydes including vanillin, syfingaldehyde, coniferaldehyde, siaapaldehyde, and ethyl lignin come from charred wood, the length of matufing directly affects the amount of aldehydes formed, the lower proof spirits have more aldehydes than higher proof spirits do, and the used and new uncharred barrels produce about one-third of the aromatic aldehydes found ia new charred barrels (Table 3) (8). 

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 —... 

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 —... 

Sadtler concluded finally that double bonds seem to aid in bringing about reaction when close to the. CHO group, e.g., citral, cinnamic aldehyde, and that proximity of the benzene nucleus to the. CHO group, as. in the case of benzaldehyde and vanillin, was also probably a factor, while the only active ketones were those containing double bonds near to the. CO group. 

Aromatic aldehydes. Benzaldehyde, vanillin, and cinnamaldehyde are aldehydes with pleasant aromas that are found in almonds, vanilla beans, and cinnamon, respectively. 

It was decided to construct a D-ring acylating agent bearing a latent C-8 vinyl group. To this end, benzylation of the known 5-bromo-orr/to-vanillin (22),14 followed by protection of the aldehyde carbonyl in the form of a cyclic acetal (1,3-dioxane), affords com-... 

Protocatechualdehyde has been made by a variety of methods, but is usually prepared from catechol by the Reimer-Tiemann method 1 by demethylation of vanillin,2 or veratric aldehyde 3 or from piperonal by the action of phosphorus pentachloride followed by hydrolysis.4... 

Aldehydes occur naturally in essential oils and contribute to the flavors of fruits and the odors of plants. Benzaldehyde, C6H5CHO (8), contributes to the characteristic aroma of cherries and almonds. Cinnamaldehvde (9) is found in cinnamon, and vanilla extract contains vanillin (10), which is present in oil of vanilla. Ketones can also be fragrant. For example, carvone (Section 18.1) is the essential oil of spearmint. 

Many known color reactions involve electrophilic substitution at an electron-rich aromatic or heteroaromatic (cf. 4-(dimethylamino)-benzaldehyde - acid reagents and vanillin reagents ). Here aliphatic or aromatic aldehydes react in acid medium to yield polymethyne cations which are intensely colored di- or triarylcarbenium ions [4, 10]. 

Classical examples of this type of reaction are the various dimethylaminobenz-aldehyde reagents (q.v.) and vanillin-acid reagents, of which one, the vanillin-phosphoric acid reagent, is already included in Volume 1 a. The aldol condensation of estrogens is an example for the reaction mechanism (cf. Chapter 2, Table 6). According to Maiowan indole derivatives react in a similar manner [1]. Longo has postulated that catechins yield intensely colored triphenylmethane dyes [2]. 

Aromatic aldehydes react in basic as well acidic medium. Thus vanillin and primary amines yield Schiff s bases (cf. vanillin-potassium hydroxide reagent in Volume 1 a). Colored phenolates are formed at the same time. As would be expected secondary amines, indole derivatives and lysergic acid derivatives do not react. 

The vanillin ethers 36 and 39 exhibited the IR band of the lactone carbonyl group at 1710-1720 cm whereas the aldehydic carbonyl stretching was observed in the range of 1680-1690 cm In the NMR spectra all the protons resonated at expected fields. The aldehydic proton appeared downfield around 9-10 aromatic protons in the range of 7-8 and the C3 - H of coumarin around 6.5. The methylene, methoxy, and methyl protons resonated around 5, 3.8, and 2.2, S respectively. 

Addition of a little of the aldehyde (vanillin) to a strong solution of the trihydrated nitrate in 90% formic acid led to a violent (redox) reaction. 

Treatment of suberin with nitrobenzene generates vanillin, p-hydroxy benz-aldehyde, but not much syringaldehyde that arises mostly from lignin. 

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