Benzoic acids aromatic compounds benzoylation

The ditellurium compounds, in which a Te —Te group joins two carbonyl groups, can be considered to be the tellurium analogs of peroxy compounds derived from carbonic acid or benzoic acids (e.g. benzoyl peroxides). Only a few of these compounds are known. During the reduction of aromatic nitro compounds with disodium telluride in dimethylfor-mamide, bis[dimethylaminocarbonyl] ditellurium was formed as a by-product in yields from 5 to 15%. The formation of this compound was attributed to the capture of the dimethylaminocarbonyl radical by the telluride anion and subsequent oxidation of the tellurocarbamoyl species4. 

Electron-rich aromatic compounds such as durene, p-dimethoxybenzene, mesitylene, anisole, thiophene, and fluorene can be benzoylated or acetylated by the corresponding Af-acylimidazole in trifluoroacetic acid to give the corresponding benzophenone or acetophenone derivative in good yield (Method A). As the actual acylating agent, a mixed anhydride of trifluoroacetic acid and benzoic acid has been proposed 1973... 

Cs2 5Ho.5PW 2040 (Cs2.5) catalyzes the acylation of aromatic compounds with benzyl chloride, benzoyl chloride, benzoic anhydride, benzoic acid, or acetic acid (214). As shown in Table XXII, H3PW 2O40 is usually less active than... 

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). 

The benzoylation of both activated and deactivated aromatic compounds with benzoic acids (BACs) is achieved by using bismuth triflate (10% mol) in the presence of TFAA or heptafluorobutyric anhydride (HFBA).27 meffl-Xylene undergoes acetylation with 100% yield by using acetic acid (AAC) in the presence of TFAA under bismuth or scandium triflate catalysis (10% mol). The bismuth-triflate-catalyzed reaction can be extended to different aromatics as well as to aliphatic and aromatic carboxylic acids, giving ketones in nearly quantitative yield. Benzene and chlorobenzene are benzoylated with a BAC/HFBA mixture in the presence of bismuth triflate (10% mol), giving the corresponding BPs in 90%... 

Aromatic compounds can also be degraded anaerobically, via reductive pathways, which have been reviewed. The best-characterized example is the degradation of benzoic acid in Rhodopseudomonas palustris and Thauera aromatica via the pathway shown in Figure 8. Benzoyl-CoA is formed, and then a reductase enzyme is able to reduce the aromatic ring to a cyclohexadiene. Following two consecutive additions of water, and oxidation to a /3-keto ester, hydrolytic cleavage gives a linear 7-carbon CoA thioester, which can then be broken down via fatty acid /3-oxidation. 

Acetophenone possesses the properties characteristic of aromatic compounds. When heated with dilute nitric acid it is oxidized to benzoic acid with concentrated nitric acid nitro derivatives are formed. The chief product of nitration is m-nitro-acetophenone a small proportion of the ortho compound is also formed. p-Nitroacetophenone can be prepared from p-nitro-benzoyl chloride and acetoacetic ester. 

The simplest aromatic carboxylic acid is benzoic acid (8-72), which is relatively widespread in plant materials, mainly as 1-O-benzoyl-P-D-glucopyranose (see Section 4.3.3.3), but both compounds are non-volatile polar substances that do not have any impact on food flavour. In essential oils, benzoic acid is found in the form of flavour-active esters. Benzoic acid arises from cinnamic acid or cinnamoyl-CoA through side-chain shortening by a C2 unit. Its content in fruits and vegetables is generally very low, at around 0.05%. In cranberries it is present predominantly as 6-O-benzoyl-P-D-glucopyranose, known as vaccinin (see 4-92), in an amount of around 0.2%. Free benzoic acid is also present in a very small amount (about 0.0015%) in yoghurts where it results from hippuric acid hydrolysis. It is often also added to foods as a preservative. A typical example of a preserved product is table mustard, where concentrations of benzoic acid typically reach 1000 mg/kg. 

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