Benzaldehyde

Abstract

Benzaldehyde is the simplest and quite possibly the most industrially useful aromatic aldehyde. It is manufactured from toluene, either by chlorination, followed by hydrolysis, or by liquid phase air oxidation. The air oxidation of toluene to produce benzoic acid is the source of most of the world's synthetic benzaldehyde. Benzaldehyde is widely used directly, as a synthetic flavoring substance, or as a raw material in the synthesis of industrially important derivatives such as benzyl alcohol, benzoin and benzil and several benzyl amines. The hydrogenation of benzaldehyde to form benzyl alcohol is the largest single use of benzaldehyde. In addition, benzaldehyde serves as the major raw material a wide variety of fragrance compounds are derivatives of benzaldehyde. The major products in the fragrance category are cinnamic aldehyde and a number of substituted cinnamic aldehydes; such as methyl, butyl, amyl, and hexyl cinnamic aldehydes.

Metal-Free Dehomologative Oxidation of Arylacetic Acids for the Synthesis of Aryl Carboxylic Acids

“…Thus, the development of novel methods for their synthesis is of great interest to organic chemists. Conventionally, benzoic acid is prepared via partial oxidation of toluene using cobalt or manganese naphthenates as catalysts . The global production capacity of aryl carboxylic acids was estimated to be 480000 tons in 2014 and is likely to exceed 620000 tons by 2023 with gains of over 3.2% from 2016 to 2023 .…”

“…Aryl carboxylic acids have also been prepared from various starting materials (Figure ). ,, Recently, Wu et al have reported a novel protocol for the preparation of aryl carboxylic acids via palladium-catalyzed hydroxycarbonylation of aryl halides . However, the inherent drawback of either environmental pollution or difficulty in metal reagent separation from the products is associated with the stoichiometric use of metallic oxidants.…”

Nondirected, Cu-Catalyzed sp3 C–H Aminations with Hydroxylamine-Based Amination Reagents: Catalytic and Mechanistic Studies

“…Benzylic amines are important substructures in biologically active compounds; however, the synthesis of such structures is typically achieved through functional group interconversion processes. − Direct aminations of benzylic C–H bonds would streamline the synthesis of benzylic amines, − in particular, if first-row transition metals can be employed as catalyst precursors. Efforts to this end have recently produced a series of Co − and Cu catalysts ,− that achieve nondirected, intermolecular benzylic C–H aminations.…”

Prospects of Z-Scheme Photocatalytic Systems Based on Metal Halide Perovskites

“…Specifically, the industrial synthesis of benzlaldehyde proceeds with the liquid phase air oxidation of toluene at elevated temperature (136−160 °C) and pressure (2−7 atm) using a soluble cobalt catalyst. 121 Research is ongoing to improve on these nonideal conditions, for example, by the use of MnWO 3 catalysts that enable the reaction to proceed at a lower temperature (80 °C) but only when using H 2 O 2 as an oxidant. 122 In an alternative photocatalytic process, a MHP-based catalyst can support light-driven in situ reduction of O 2 to superoxide (O 2 − ) and efficiently oxidize toluene to benzaldehyde under ambient conditions.…”

“…In other cases, such as the oxidation of toluene to benzaldehyde, both industrial and other nonphotocatalytic processes exist. Specifically, the industrial synthesis of benzlaldehyde proceeds with the liquid phase air oxidation of toluene at elevated temperature (136–160 °C) and pressure (2–7 atm) using a soluble cobalt catalyst . Research is ongoing to improve on these nonideal conditions, for example, by the use of MnWO 3 catalysts that enable the reaction to proceed at a lower temperature (80 °C) but only when using H 2 O 2 as an oxidant .…”