Phenolic compounds acetylations, pyridine

As mentioned earlier, meso-inositol, and indeed all the inositols, are readily converted to aromatic compounds by oxidation. Posternak found that inosose has the tendency to form phenolic compounds under very mild conditions. On attempted acetylation of inosose with acetic anhydride in the presence of either pyridine or sodium acetate the expected pentaacetate was not obtained the product was 1,2,3,5-tetra-acetoxybenzene (XXXVII). Similarly, the treatment of inosose pentaacetate with boiling acetic anhydride and pyridine or sodium acetate gave the same product. Inosose pentabenzoate was prepared by the use of benzoyl chloride and zinc chloride. Under the influence of pyridine or sodium acetate in acetic acid the pentabenzoate lost two molecules of benzoic acid to give l-hydroxy-2,3,5-tribenzoxybenzene (XXXVIII). 

Chemically modified polymeric sorbents have also been introduced in the recently years. The introduction of polar groups such as alcohol, acetyl, and the sulfonate group into PS-DVB greatly increases the retention of polar organic compounds. The comparative recovery study was performed for extraction of polar compounds such as phenols, aromatic, and pyridinic compounds with three types of PS-DVB-based sorbents and C-18 silica the results are shown in Table 10.5. The recoveries by using PS-DVB-CH3OH... 

Phenarsazine oxide crystallises from nitrobenzene or pyridine in colourless plates, which soon become yellow, M.pt. 350° C. It is sparingly soluble in most solvents, and when boiled with alcohols yields ethers, and with phenols, phenyl ethers. Boiling with acetic acid transforms it into 10-acetyl-S lO-dikydrophenarsazine, which occurs in greenish, shimmering plates, M.pt. 228° to 224° C. The corresponding 10-n-butoxy-compound forms pale yellow needles, M.pt. 158° to 160° C., and the lO-hemsyhtxy-denvaiive, colourless needles, M.pt. 178° to 175° C. 

Aromatic acid chlorides (ArCOCl) are considerably less reactive than the aliphatic acid chlorides. With cold water, for example, acetyl chloride reacts almost explosively, whereas Benzoyl chloride reacts only very slowly. The reaction of aromatic acid chlorides with an alcohol or a phenol is often carried out using the Schotten-Baumaiin technique the acid chloride is added in portions (followed by vigorous shaking) to a mixture of the hydroxy compound and a base, usually aqueous sodium hydroxide or pyridine (an organic base, Sec. 31.11). Although the function of the base is not clear, it seems not only to neutralize the hydrogen chloride that would otherwise be liberated, but also tp catalyze the reaction. 

The tautomeric mixture was acetylated employing Ac20/pyridine in order to facilitate the structural analyses and two tri-acetylated compounds were obtained. Aristophenone is similar to clusianone the main difference was associated with the different substitution of phenolic ring. 

The studies have been extended to esters that contain condensed polyaromatics in the phenolic substructure. For instance, 1-naphthyl acetate gives 2- and 4-acetyl-1-naphthols [22, 30, 42], whereas in the case of 2-naphthyl acetate, 1-, 3-, 6-, and (marginally) 8-acetyl-2-naphthols are obtained [27, 49-53]. The reaction also works with heterocyclic compounds, such as furan [54], pyridine [55-57], indole [58-60], or chromane [61] derivatives. 

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