Benzoic aldehyde, benzaldehyde

BENZALDEHYDE Benzoic Aldehyde, Oil of Bitter Almond Combustible Liquid 2 2 0 ... 

Trinitrotoluene 2,4,6-Trinitrotoluene Benzaldehyde Benzoic aldehyde Benzoic acid Catechaldehyde... 

C.39) (C.39) Benzaldehyde, benzaldehyde, benzoic aldehyde, benzenecarboxaldehyde, phenylmethanal (100-52-7] FEMA 2127... 

Benzaldehyde, benzoic aldehyde, CeHs.CHO, occurs in amygdalin, a glucoside which is present in bitter almonds and in the kernels of various fruits it yields the aldehyde, hydrocyanic acid, and glucose on hydrolysis (353). The aldehyde is called oil of bitter almonds. It is used in flavoring extracts and perfumery, in the manufacture of certain dyes, and in the preparation of other compounds. 

Wines stored in vats lined with epoxy resins can present unusually high levels of benzoic aldehyde (several mg/L). Benzylic alcohol is both a plasticizer and diluent of these resins. Its conversion into benzaldehyde can be due (Blaise 1986) to the action of an exocellular enzyme of Botrytis cinerea called Alcohol Benzylic Oxidase (ABO, E.C. 1.1.3.7.) responsible for this oxidation process (Blaise and Brun 1986). 

Benzyl Alcohol.—The simplest aromatic alcohol is the hydroxyl derivative of toluene and is known as benzyl alcohol, CeHs—CH2—OH. The radical, (CeHs—CH2—), is termed benzyl as in the alcohol and chloride above. The alcohol occurs as an ester in Peru balsam, in storax, a resin obtained from a plant sty rax, and in Tolu balsam from which the mother hydrocarbon toluene derives its name. On hydrolysis of the balsam benzyl alcohol is obtained. It is a liquid, b.p. 206.5°, slightly soluble in water and soluble in alcohol or ether. It may be prepared by those syntheses just given which yield primary alcohols. It may also be prepared by the reduction of the corresponding aldehyde, known as benzoic aldehyde or benzaldehyde (p. 655). On oxidation it yields the aldehyde and then an acid, benzoic acid. 

In this paper, we wish to report on the selective oxidation of 5-hydroxymethylfurfural to 2,5-furan-dicarboxaldehyde using vanadium oxide supported on titanium oxide with different vanadium loadings. If we take into account the large differences in the activation energies reported over V2O5 in the oxidation sequence benzyl alcohol --> benzaldehyde (Eg = 26 kJ/mol) and benzaldehyde > benzoic acid (Eg = 55 kJ/mol) [10], those catalytic systems were then expected to stop at the aldehyde stage by working at low temperatui e. 

BZ was al so partially oxidized by Ag(II) in a small H-cell with stationary platinum electrodes. Compounds identified in anolyte extracts included phenol, hydroquinone, benzoquinone, benzaldehyde, benzoic acid, methyl benzoate, benzonitrile, benzonitrile aldehyde, and 4-nitro butylnitrile. The yellow color of the anolyte was probably due to benzoquinone, which had a relatively high concentration. A compound which was tentatively identified as benzoquinone epoxide ( 11403) was present at the highest concentration and is believed to be a product of the oxidation of benzoquinone. Numerous nitrated aromatics were also detected and include nitrobenzene, dinitrobenzene isomers, nitrophenol isomers, and dinitnophenol isomers. Intermediates are summarized in Table 3 and classified as I. BZ substrate II. nitrated BZs HI. phenols, quinones, and epoxides IV. nitrated phenols V. BZ substituted with aliphatic and aromatic... 

Benzaldehyde, benzoic acid and benzene also exhibit substantial inhibiting effect on the hydrogen reaction [45—47]. The hydrogen evolution inhibitors are adsorbed at the protons that are mainly present on the antimony sites (catalytic centres) of the electrode surface. Boehnsted et al. [45] propose a mechanism of the specific adsorption of aromatic aldehydes on these sites [45]. 

Benzoic aldehyde. See Benzaldehyde Benzoic ether. See Ethyl benzoate Benzoic trichloride. See Benzotrichloride Benzoin... 

Benzaldehyde ben- zal-di3- hld [ISV] (1866) (benzoic aldehyde, oil of bitter almonds, benzoyl hydride, benzene carbo-nal) n. CgHsCHO. A solvent, particularly for polyester and cellulosic plastics (See image). 

Cannizzaro reaction Two molecules of many aldehydes, under the influence of dilute alkalis, will interact, so that one is reduced to the corresponding alcohol, while the other is oxidized to the acid. Benzaldehyde gives benzyl alcohol and benzoic acid. Compare the aldol condensation. 

Separations based upon differences in the chemical properties of the components. Thus a mixture of toluene and anihne may be separated by extraction with dilute hydrochloric acid the aniline passes into the aqueous layer in the form of the salt, anihne hydrochloride, and may be recovered by neutralisation. Similarly, a mixture of phenol and toluene may be separated by treatment with dilute sodium hydroxide. The above examples are, of comse, simple apphcations of the fact that the various components fah into different solubihty groups (compare Section XI,5). Another example is the separation of a mixture of di-n-butyl ether and chlorobenzene concentrated sulphuric acid dissolves only the w-butyl other and it may be recovered from solution by dilution with water. With some classes of compounds, e.g., unsaturated compounds, concentrated sulphuric acid leads to polymerisation, sulphona-tion, etc., so that the original component cannot be recovered unchanged this solvent, therefore, possesses hmited apphcation. Phenols may be separated from acids (for example, o-cresol from benzoic acid) by a dilute solution of sodium bicarbonate the weakly acidic phenols (and also enols) are not converted into salts by this reagent and may be removed by ether extraction or by other means the acids pass into solution as the sodium salts and may be recovered after acidification. Aldehydes, e.g., benzaldehyde, may be separated from liquid hydrocarbons and other neutral, water-insoluble hquid compounds by shaking with a solution of sodium bisulphite the aldehyde forms a sohd bisulphite compound, which may be filtered off and decomposed with dilute acid or with sodium bicarbonate solution in order to recover the aldehyde. 

Further substitution of benzoic acid leads to a drug with antiemetic activity. Alkylation of the sodium salt of p-hydroxy-benzaldehyde (8) with 2-dimethylaminoethyl chloride affords the so-called basic ether (9). Reductive amination of the aldehyde in the presence of ammonia gives diamine, 10. Acylation of that product with 3,4,5-trimethoxybenzoyl chloride affords trimetho-benzamide (11). ... 

The Cannizzaro reaction takes place by nucleophilic addition of OH- to an aldehyde to give a tetrahedral intermediate, which expels hydride ion as a leaving group and is thereby oxidized. A second aldehyde molecule accepts the hydride ion in another nucleophilic addition step and is thereby reduced. Benzaldehyde, for instance, yields benzyl alcohol plus benzoic acid when heated with aqueous NaOH. 

Aldehydes, and particularly aromatic ones, are highly susceptible to autoxidation thus benzaldehyde (97) is rapidly converted into benzoic acid (98) in air at room temperature. This reaction is catalysed by light and the usual radical initiators, but is also highly susceptible to the presence of traces of metal ions that can act as one-electron oxidising agents (cf. p. 306), e.g. Fe3 , Co3 , etc ... 

The method uses a simple electrode made of a thin film of sol-gel organosilica doped with nitroxyl radicals deposited on the surface of an indium tin oxide (ITO) electrode. Thus, whereas in water benzyl alcohol is rapidly oxidized to benzoic acid, the use of the hydrophobic sol-gel molecular electrode TEMPO DE affords benzaldehyde only (Figure 1.9), with an unprecedented purity, which is highly desirable for the fragrance and pharmaceutical industries where this aromatic aldehyde is employed in large amounts. 

Analogously, the use of m-chloroperbenzoic acid (MCPBA) or the in situ formation of peroxy acids by means of a sacrificial aldehyde (typically benzaldehyde plus molecular oxygen as a source of perbenzoic acid [20, 21]) are not viable processes, from an industrial point of view, because of the very poor atom efficiency and the huge formation of benzoic acids as side products. 

Benzene-l,4-diols are oxidized to quinones by benzyltrimethylammonium tribromide under mild conditions in almost quantitative yields [6]. With an excess of the tribromide further reaction produces the 2-bromo-l, 4-quinones. This oxidation is in contrast to the analogous reaction of phenols, which produces bromophenols (see Section 2.3). Hindered 4-methyl-phenols are oxidized to the corresponding benzyl alcohols, benzaldehydes, bromomethyl derivatives and 4-bromo-4-methylcyclo-hexa-2,5-dien-l-ones [7]. Benzylic alcohols are oxidized under neutral or basic conditions to yield the corresponding aldehydes (>70%) oxidation with an excess of the reagent produces the benzoic acids (>90%) [8],... 

The condensation of 2-hydroxyacetophenone with benzaldehyde yielded exclusively 2 -hydroxy-chalcone, and the cyclization to flavanone was not observed. An investigation of the species adsorbed on the catalyst (289) suggested that CS condensation on the Ba(OH)2 surface occurs via a very rigid transition state, whereby the OH group of 2-hydroxyacetophenone is bonded to the catalyst surface and placed at great distance from the carbonyl carbon atom of the aldehyde, making the cyclization of 2 -hydroxy-chalcone to flavanone difficult. Deactivation of the catalyst was not observed in the presence of moderate amounts of organic acids, such as benzoic, acrylic, or trichloroacetic acid. 

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