Orcinol compounds

The most common phenolic acid units derived by the acetate-polymalonate pathway and combined to form the characteristic lichen substances are of two types the orcinol-type units and p-orcinol-type units. While compounds formed from these two types of units are similar in many ways, differences in their structure and especially in their distributimi among the lichens suggest that the usual tendency to consider the orcinol and p-orcinol compounds separately probably has a biosynthetic justification. 

P-orcinol series The orcinol-type compounds discussed in the previous section form a closely related series of substances in which changes in the length and oxidation state of the 6-alkyl substituents are major sources of variation among phenolic units. The compounds synthesised by various combinations of these units show secondary modifications attributable to 0-methylation, chlorination, decarboxylation and lactonisation. The p-orcinol compounds may undergo all of the same secondary reactions, but the most common variation is in the oxidation state of the Cj substituents at the 3- and 6-positions of the phenolic acid units. 

Oakmoss. Extracts of oakmoss are extensively used in perfumery to furnisli parts of the notes of the fougnre or chypre type. The first step in the preparation of an oakmoss extract is treatment of the Hchen Evemiaprunastri (L.) Ach., collected from oak trees mainly in southern and central Europe, with a hydrocarbon solvent to obtain a concrete. The concrete is then further processed by solvent extraction or distillation to more usable products, of which absolutes are the most versatile for perfumery use. A definitive analysis of oakmoss volatiles was performed in 1975 (52). The principal constituents of a Yugoslav oakmoss are shown in Table 15 (53). A number of phenoHc compounds are responsible for the total odor impression. Of these, methyl P-orcinol carboxylate is the most characteristic of oakmoss. 

Wang et al. (62) reported the oxidative polymerization of a mixture of phenolic compounds in aqueous solution containing mont-morillonlte, illite, and kaolinite, each of which had been mixed with quartz in a 3 7 ratio, and by quartz alone. The mixture of phenolic compounds contained gallic acid, pyrogallol, protocatechuic acid, caffeic acid, orcinol, ferulic acid, p-coumaric acid, syringic acid, vanillic acid, and p-hydroxybenzoic acid. The oxidative... 

By careful choice of both the reaction conditions and the phenolic compound used, it may be possible to produce a colour that is characteristic of a particular carbohydrate or related group, so giving some degree of specificity to the method. Thus, Seliwanoff s test uses hydrochloric acid and either resorcinol or 3-indolylacetic acid to measure fructose with minimal interference from glucose. The colour produced by pentoses with orcinol (Bial s reagent) or p-bromoaniline is sufficiently different from that produced by hexoses to permit their quantitation in the presence of hexoses. However, none of the methods based on the formation of furfural or its derivatives can be considered to be entirely specific. 

Chlorinated orcinol derivatives have been isolated from diseased bulbs of the edible lily Lilium maximowiczii. The antifungal activity of these compounds was tested against Bipolaris leersiae. Inhibition of the conidial germination depends on the number of chlorine atoms in the compounds. The trichlorinated orcinol 156 shows the highest activity. Dichlorinated orcinols, e.g. 157, are next, and the monochlorinated ones, e.g. 158, are still less active. The nonchlorinated orcinol shows lowest activity [121]. 

Compound from 2-Nitrore orcinoL—This nitrophenol yields the substance (C6H5)4Cr.0.C6H3(N02).0.Cr(C H6)4.2(H0)2C6H3.N02, consisting of olive-coloured crystals, melting with decomposition at 162 5° C. 

V.p.c. analysis of the product on two columns (silicone gum rubber SE-30 and OV-1) indicated the presence of traces of two other compounds with retention times longer than that of orcinol dimethyl ether. These impurities, which were most likely C-methylated materials,2 totaled less than 0.5% of the product. 

Monde K, Satoh H, Nakamura M, Tamura M, Takasugi M (1998) Organochlorine Compounds from a Terrestrial Higher Plant Structures and Origin of Chlorinated Orcinol Derivatives from Diseased Bulbs of Lilium maximowiczii. J Nat Prod 61 913... 

The dibromo compound is dehalogenated by agitating under a hydrogen atmosphere a mixture of 80 g. (0.23 mole) of the dibromo compound, 700 ml. of N aqueous sodium hydroxide solution, and a catalyst consisting of 2% palladium on polyvinyl alcohol prepared from 0.5 g. of palladium chloride (p. 244). To the resulting mixture is added 120 g. of sodium chloride, and the precipitated catalyst is removed by filtration. The filtrate is acidified and extracted with chloroform. Removal of the chloroform by distillation gives 35 g. (80%) of ethyl orcinol-6-carboxylate, m.p. 132-133°. 

By heating with HCl, pentoses are converted to furfural, which reacts with orcinol to form green compounds. Dissolve 300 mg of orcinol in 100 mL of concentrated HCl and... 

Monde, K., H. Satoh, M. Nakamura, M. Tamura, and M. Takasugi. 1998. Organochlo-rine compounds from a terrestrial plant structures and origin of chlorinated orcinol derivatives from diseased bulbs of Lilium maximowiczii. ]. Nat. Prod. 61 913-921. 

Malonylidene nitrile and a dilorine are transformed into a fused pyran-2-one ring when heated with ethanolic hydrogen chloride [3002]. Reactions in which nitriles and hydrogen chloride interact have been reviewed [2547], When a 2-bromobenzamide is heated with orcinol in dilute sodium hydroxide containing copper(II) sulphate, the bromo and amino groups are lost C—C and C—O bon are formed in a synthesis of the dimethyl ether of altemariol, a compound found in some plants of the Liliacae family [2922]. 

In 1907, Collie showed that dehydroacetic acid is converted into orcinol (128) on treatment with base. ° It was presumed that this transformation proceeds through triketone (127 equation 148). On the basis of this reaction, Collie suggested the polyacetate biogenesis of naturally occurring phenolic compounds. In later work, it was shown that trione (127) is converted by acid into phenol (128). - 2... 

A new synthesis of grifolin (9), involving treatment of farnesyl chloride (8) with orcinol (7) in the presence of sodium, is reported to give a better yield than the various syntheses previously recorded for this compound (c/. Vol. 5, p. 91). 

Orcinol upon treatment dropwise with 2-methyl-3-buten-2-ol in warm aqueous formic acid at 80°C and reaction for 1 hour afforded 5-methyl-4-(3-methylbuten-2-yl)resorcinol in low yield while from the filtrate of the reaction mixture, the isomeric compound, 5-methyl-2-(3-methylbuten-2-yl)resorcinol was isolated as well as a bis-prenyl compound by chromatographic purification (ref.16). 

By reaction of geraniol with orcinol in 1% oxalic acid two isomeric monoprenyl compounds were obtained although with aqueous formic acid substantial amounts of cyclised products resulted. 

Although many of the complex natural chromene, chroman, pyran and benzofuran structures clearly have arisen from reactive prenyl precursors which themselves have invariably not been isolated, certain prenyl derivatives of dihydric phenols have served as model compounds in cyclisation processes likely to be the pathways towards those naturally occurring compounds. 2-Prenylphenols and 2- and 4-prenylresorcinols and orcinols with C5, C o, and... 

Alkyl Bound to Carbon. These compounds may be considered as being derived by the substitution of an alkyl group for hydrogen in carbon compounds. Examples are alkylate for synthetic gasoline, ethylbenzene for styrene entering into the manufacture of plastics and rubber, and hexylres-orcinol, thymol, barbital, and other barbituric acid alkyl derivatives. 

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