Phenol-aldehyde compounds

Blumer described a composition which could be used in the manufacture of coatings, based on phenol aldehyde compounds reacted with epichlorohydrin. 

High reactivity contaminants phenols, aldehydes, aromatics, amines, some sulfur compounds. 

Phenolics, A class of thermoset resins made by the condensation of phenol or phenol-containing compounds with aldehydes such as acetaldehyde or formaldehyde. 

There is also evidence that at least some of the phenolic aldehydes and dehydrodiferulic acid (Figure 1) are linked covalently to cell wall polysaccharides. When ryegrass cell walls were treated with cellulase, the aldehydes and the acid were released as water-soluble carbohydrate-aromatic compounds from which the aromatics were released by cold sodium hydroxide treatment (6,7). This suggests that these compounds are either ether-linked or, in the case of the acid, ester-linked to the polysaccharides. 

Terpenes are polymers of the 5-carbon compound isoprene (Figure 1.12) and, as such, generally display properties similar to those of hydrocarbons. Terpenoids are substituted terpenes (i.e. contain additional chemical groups, such as an alcohol, phenols, aldehydes, ketones, etc.). Only a few such substances could be regarded as true drugs. Terpenes, such as limonene, menthol and camphor, form components of various essential oils with pseudo-pharmaceutical uses. A number of these molecules, however, exhibit anti-tumour activity, of which taxol is by far the most important. 

Alkaline hydrolysis of benzal acetone structures to the corresponding aldehyde (XIX) and acetone and subsequent oxidation of the aldehyde (XIX) to the corresponding benzoic acid (V) do not seem to represent an actual degradation stage since oxidizing the aldehyde (XIX) under our mild standard conditions yielded only traces of the corresponding benzoic acid (V). The aldehyde (XIX) was rapidly decomposed via Dakin reaction to formic acid and 3-methoxy-S-methyl-o-benzoquinone, which is immediately degraded to phenolic humic compounds. 

Figure 2, Phenols, aldehydes, carboxylic acids, and other aromatic compounds with growth-regulating activity...

Figure 1 illustrates the fact that resins and adhesives formed by the possible combinations of a phenolic compound, a nitrogenous compound, an aldehyde compound, and a carbohydrate have been reported in the literature. The exact conditions used to formulate the resins and adhesives represented in Figure 1 vary considerably. For example, additional circles representing acidic, basic, and neutral reaction conditions could be added. In most instances, the exact chemistry that occurs during the formulation of resins at each intersection is not known. Indeed, in many cases, the component actually reacting into the resin or adhesive system may not be the original carbohydrate added at the start. In this and other respects, these formulations will overlap with those discussed in the next section. 

Nitrogenous compound-Aldehyde-Carbohydrate (NAC) Phenol-Nitrogenous compound- 99,104-113... 

This reaction is readily accomplished by heating the phenolic compound at 150-160 for 10 to 30 minutes with a mixture of glycerol, boric acid, and hexamine. The phenolic aldehyde is liberated by acidification and steam distillation. By this general procedure, sixteen phenolic aldehydes have been prepared. Although the yields are only 15-20%, the method requires little time and furnishes a reasonably pure product which is the ortho isomer (cf. method 143). 

Alcohol-aldehydes and -ketones.— If the hydroxyl group in hydroxy aldehydes and ketones is in the side chain instead of the ring then the compounds instead of being mixed phenol-aldehydes will be alcohol-aldehydes or -ketones c.g.,... 

Perkin Synthesis of Coumarin.—Coumaric acid and coumarin may be synthesized by the Perkin reaction for synthesizing unsaturated aromatic acids (p. 698). These syntheses are of historical interest as the two compounds obtained were the first onesprepared by this reaction. Instead of taking a simple aromatic aldehyde it is only necessary to take a phenol aldehyde viz., salicylic aldehyde,... 

---