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The Étard reaction is a chemical reaction that involves the direct oxidation of an aromatic or heterocyclic bound methyl group to an aldehyde using chromyl chloride. [1] [2] [3] For example, toluene can be oxidized to benzaldehyde. It is named for the French chemist Alexandre Léon Étard (5 January 1852, Alençon – 1 May 1910).
Then the benzylammonium undergoes an acid-catalyzed hydrolysis process. Depending on the hydrolysis conditions, the hexamine unit might instead break apart, leaving a benzyl amine (the Delépine reaction). The reaction can also be applied to the oxidation of benzylic amines. In this way, m-xylylenediamine can be converted to isophthalaldehyde. [5]
Benzaldehyde (C 6 H 5 CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is among the simplest aromatic aldehydes and one of the most industrially useful. It is a colorless liquid with a characteristic almond -like odor , and is commonly used in cherry -flavored sodas . [ 5 ]
The same conversion can be effected with elemental bromine in the presence of UV light or even sunlight. Toluene may also be brominated by treating it with HBr and H 2 O 2 in the presence of light. [31] C 6 H 5 CH 3 + Br 2 → C 6 H 5 CH 2 Br + HBr. Benzoic acid and benzaldehyde are produced commercially by partial oxidation of toluene with oxygen.
The reaction is usually carried out in two steps in the same pot: partial oxidation is effected with TEMPO and hypochlorite, then chlorite is added to complete the oxidation. Only primary alcohol oxidation is observed. In conjunction with Sharpless dihydroxylation, this method can be used to generate enantiopure α-hydroxy acids. [19]
Photoexcitation is the first step in a photochemical process where the reactant is elevated to a state of higher energy, an excited state.The first law of photochemistry, known as the Grotthuss–Draper law (for chemists Theodor Grotthuss and John W. Draper), states that light must be absorbed by a chemical substance in order for a photochemical reaction to take place.
Reductive elimination is an elementary step in organometallic chemistry in which the oxidation state of the metal center decreases while forming a new covalent bond between two ligands. It is the microscopic reverse of oxidative addition, and is often the product-forming step in many catalytic processes. Since oxidative addition and reductive ...
In the classic example, benzaldehyde is converted to benzoin (PhCH(OH)C(O)Ph). [3] The benzoin condensation was first reported in 1832 by Justus von Liebig and Friedrich Wöhler during their research on bitter almond oil. [4] The catalytic version of the reaction involving cyanide was developed by Nikolay Zinin in the late 1830s. [5] [6 ...