Hexamethylenetetramine , Sommelet reaction

Bromomethyl-2,3-dimethoxy-7-methylquinoxaline (265) underwent a classical Sommelet reaction and incidental hydrolysis of the methoxy groups to give 7-methyl-2,3-dioxo-l,2,3,4-tetrahydro-6-quinoxalinecarbaldehyde (266) (hexamethylenetetramine, CHCI3, 20°C reflux, 30 min solid from evapora-... 

Naphthaldehyde has been made from a-naphthonitrile by reduction with stannous chloride, and from naphthalene by the action of aluminum chloride, hydrogen cyanide, and hydrochloric acid. The best preparation is the Sommelet reaction from a-chloro- or a-bromomethylnaphthalene and hexamethylenetetramine in aqueous alcohol is.is. .is.w or glacial acetic acid. This method has been improved in the present procedure by the use of 50% acetic acid as solvent. 

Another way to oxidize primary alkyl halides to aldehydes is by the use of hexamethylenetetramine followed by water. However, this reaction, called the Sommelet reaction. is limited to benzylic halides. The reaction is seldom useful when the R in RCH2CI is alkyl. The first part of the reaction is conversion to the amine ArCH2NH2 (0-44), which can be isolated. Reaction of the amine with excess hexamethylenetetramine gives the aldehyde. It is this last step that is the actual Sommelet reaction, though the entire process can be conducted without isolation of intermediates. Once the amine is formed, it is converted to an imine (ArCH2N=CH2) with formaldehyde liberated from the reagent. The key step then follows transfer of hydrogen from another mole of the arylamine to the imine ... 

SOMMELET REACTION. Preparation of aldehydes from aralkyl or alkyl halides by reaction with hexamethylenetetramine followed by mild hydrolysis of the formed quaternary salt,... 

Aromatic and heteroaromatic aldehydes can alternatively be prepared from the corresponding methyl compound by subjecting the chloromethyl or bromomethyl derivative to the Sommelet reaction. This procedure involves an initial reaction between the halomethyl compound and hexamethylenetetramine (hexamine), and hydrolysing the resulting quaternary hexamine salt (4) with hot aqueous acetic acid. 

Cognate preparations. p-Nitrobenzaldehyde. This preparation is an example of the Sommelet reaction in which the hexaminium salt is isolated. Dissolve llg (0.13mol) of hexamethylenetetramine in 70ml of chloroform (CAUTION) and add 11.4 g (0.067 mol) of p-nitrobenzyl chloride or 14.4 g of p-nitrobenzyl bromide (Expt 6.28). Heat the mixture under reflux on a steam bath for 4 hours a precipitate gradually separates. Replace the reflux condenser by a condenser set for distillation and distil off about 35 ml of solvent. Add 35 ml of acetone, cool in ice, collect the precipitate by suction filtration and dry it in the air. Heat the hexaminium salt thus obtained under reflux for 1 hour with 100 ml of 50 per cent acetic acid then add 100 ml of water and 25 ml of concentrated hydrochloric acid and continue the refluxing for 5-10 minutes. Cool the solution in ice, collect the crystals of p-nitrobenzaldehyde and dry them in a vacuum desiccator. The yield is 6.4 g (63%), m.p. 106 °C. The p.m.r. spectrum is noted in Expt 6.117. 

The Sommelet reaction (Scheme 6.8) involves refluxing (chloromethyl)-benzene in aqueous ethanolic solution with hexamethylenetetramine followed by acidification. 

SCHMIDT DEGRADATION Sodium azide. SILYLATION Trimethylsilyldiethylamine. SIMMONS-SMITH REAGENT, which see. SOMMELET REACTION Hexamethylenetetramine. 

The Sommelet reaction, also known as the Sommelet oxidation, is the oxidation of benzyl halides (1) to the corresponding aldehydes (3) using hexamethylenetetramine (HMTA) followed by hydrolysis of the hexaminium salt 2.1-3 This reaction is closely related to the Delepine amine synthesis, the Duff aldehyde synthesis, and the Krtihnke reaction (see Section 7.10.3). 

In 1913, Marcel Sommelet (1877-1952) of the Faculty de Pharmacie of Paris University published his seminal article in Comptes Rendus with the title Decomposition of Alkyl Halide Addition Products of Hexamethylenetetramine, where he delineated the formation of aldehydes by treatment of benzyl halides followed by hydrolysis.4,5 In 1954, S. J. Angyal published a review in Organic Reactions, where he summarized the mechanism, scope, and limitations of the Sommelet reaction.1 Angyal s review ignited a flurry of research and the Sommelet reaction became a well-known standard for the transformation of benzyl halides to the corresponding benzaldehydes. 

A modification of the Sommelet reaction (see page 339) is to convert primary and secondary benzylamines into aldehydes by means of formaldehyde and hexamethylenetetramine. For instance, Greymore and Davies obtained benzaldehyde from benzylamine hydrochloride by this route 593 and 2-fluorene-carbaldehyde has been similarly prepared in 70% yield from 2-(aminomethyl)-fluorene hydrochloride.594 Papers by Snyder et al.595 and by M. M. Robison and B. L. Robison596 should be consulted for the reaction of tertiary amines with hexamethylenetetramine. Benzaldehydes can be synthesized by treating benzylamines with sodium nitrite and trifluoroacetic acid (molar ratio 1 2 3)... 

Aryl-4-chloromethylthiazoles (64) undergo the Sommelet reaction with hexamethylenetetramine, affording the aldehydes (66) by way of intermediate quaternary salts (65). ... 

The amidomethyl group, which is readily introduced into even deactivated rings, can be oxidized via N-bromosuccinimide and hydrolysis to give the corresponding benzaldehyde in high yield.The use of phase-transfer catalysts significantly increases the yields in Reimer-Tiemann reactions.In a recent review on the uses of hexamethylenetetramine, the scope and utility of the Duff and Sommelet reactions are discussed (ca. 30 references). ... 

Hexamethylenetetramine Aldehydes from halides Sommelet reaction... 

Sommelet process org chem The preparation of thiophene aldehydes by treatment of thiophene with hexamethylenetetramine.. so-mal ya, pra-s3s ) Sonnenschein s reagent analychem A solution of phosphomolybdicadd that forms a yellow precipitate with alkaloid sulfates. z6n-3n,shTnz r5,a-j3nt) sonocatalysis chem 1. Initiation of a catalytic reaction by irradiation with sound or ultrasound. 2. Use of sound to impart catalytic activity to a chemical compound. san-3-k3 tal-3-s3s)... 

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