Benzaldehyde from phthalic anhydride

The xanthene dyes may be classified into two main groups diphenyl-methane derivatives, called pyronines. and triphenylmethane derivatives (e.g.. (3)). which are mainly phthaleins made from phthalic anhydride condensations. A third much smaller group of rosamines (9-phenylxanthenes) is prepared from substituted benzaldehydes. The phthaleins may be further subdivided into the following fluoresceins (hydroxy substituted) Rho-damines (amino substituted), e.g.. (4) and mixed hydroxy/amino substituted. 

Desulfurization of petroleum feedstock (FBR), catalytic cracking (MBR or FI BR), hydrodewaxing (FBR), steam reforming of methane or naphtha (FBR), water-gas shift (CO conversion) reaction (FBR-A), ammonia synthesis (FBR-A), methanol from synthesis gas (FBR), oxidation of sulfur dioxide (FBR-A), isomerization of xylenes (FBR-A), catalytic reforming of naphtha (FBR-A), reduction of nitrobenzene to aniline (FBR), butadiene from n-butanes (FBR-A), ethylbenzene by alkylation of benzene (FBR), dehydrogenation of ethylbenzene to styrene (FBR), methyl ethyl ketone from sec-butyl alcohol (by dehydrogenation) (FBR), formaldehyde from methanol (FBR), disproportionation of toluene (FBR-A), dehydration of ethanol (FBR-A), dimethylaniline from aniline and methanol (FBR), vinyl chloride from acetone (FBR), vinyl acetate from acetylene and acetic acid (FBR), phosgene from carbon monoxide (FBR), dichloroethane by oxichlorination of ethylene (FBR), oxidation of ethylene to ethylene oxide (FBR), oxidation of benzene to maleic anhydride (FBR), oxidation of toluene to benzaldehyde (FBR), phthalic anhydride from o-xylene (FBR), furane from butadiene (FBR), acrylonitrile by ammoxidation of propylene (FI BR)... 

Alkylidene derivatives of phthalic thioanhydride are formed as shown in Scheme 160. Reaction of phthalic thioanhydride with hot triethyl phosphite produces trafts-S -bithioph-thalide (457), probably via the carbene and phosphorane (Scheme 161) (72AHC(14)331>. Support for this mechanism stems from the fact that brief treatment of phthalic thioanhydride with triethyl phosphite in the presence of phthalic anhydride gives (458) in the presence of benzaldehyde the same reaction leads to the benzylidene derivative (456). An alternative mechanism has also been suggested, in which the penultimate step is the formation of an epoxide, which is deoxygenated to yield the product (72AHC(14)331>. 

The low value of the raw materials compared to the premium price paid for chloride-free benzaldehyde and benzoic acid makes the commercial utilization of the process attractive despite the difficulties involved. The production of benzoic acid by the direct oxidation of toluene lias not reached the proportions that benzaldehyde has. lthough the production of beuzoic acid directly is feasible with the correct catalysts, small quantities only from this source are being marketed and are obtained as a by-product of the catalytic oxidation of toluene to benzaldehyde. Because of the difficulty in the selection of correct catalysts, the oxidation oi toluene to benzoic acid is complicated by the oxidation going too far with resultant loss of raw material or by the formation of gummy condensation products intermixed with the benzaldehyde, benzoic acid, maleic acid and anthra-quinone. These complications have deterred commercial application of the oxidation process in the face of the newer process for forming benzoic acid by the decarboxylation of phthalic anhydride. 

AUcylaromatic hydrocarbons give rise to the formation of corresponding aldehydes and carboxylic acids, for example, oxidation of toluene produces benzaldehyde[40], and phthalic anhydride can be obtained from xylene [41], Oxidation of benzene produces phenol [42], Deep oxidation of benzene gives rise to carbon dioxide and water as sole products [43],... 

Silylbenzothiazoles. 2-TrimethyIsilylbenzothiazole (84) is accessible in 75—80% yields by the addition of trimethylchlorosilane to 2-benzo-thiazolyl-lithium at - 75 C. The silicon-heterocyclic bond is unusually labile it is cleaved smoothly by benzaldehyde, with formation of the silyl-ether (85) which is hydrolysable to the alcohol (86). The cleavage by benzoyl chloride or ethyl chloroformate produces the corresponding ketone (87 R = Ph) or ester (87 R = OEt) trimethylchlorosilane is evolved from the mixture during the reaction. Phthalic anhydride yields the keto-ester (88). ... 

One of the most important selective oxidation processes in the production of chemicals is the side chain oxidation of alkyl aromatics, which are then further reacted to higher value products that end up in a variety of polymer compositions and specialised chemicals.The largest oxyfunctionalised aromatic products with regard to world production are terephthalic acid, phthalic anhydride and benzoic acid which are produced worldwide with capacities of >30,000, 5,000 and 500 kt a respectively. Worldwide production capacities for benzaldehyde and pyromel-litic dianhydride do not rise above 50 kt a In smaller capacities as specialty chemicals for the pharmaceutical industry, halo-substituted oxyfunctionalized aromatics are also produced. Of the aforementioned products, phthalic anhydride and pyromellitic dianhydride are produced from gas-phase processes using V20s-Ti02 catalysts and a liquid-phase alternative process does not appear immediately desirable. On the other hand, terephtalic and benzoic acids, and benzaldehyde are... 

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