Aldehydes chlorine atom reactions

Scollard, D. J., J. J. Treacy, H. W. Sidebottom, C. Balestra-Garcia, G. Laverdet, G. Le Bras, H. MacLeod, and S. Teton, Rate Constants for the Reactions of Flydroxyl Radicals and Chlorine Atoms with Halogenated Aldehydes, J. Phys. Chem., 97, 4683-4688 (1993). 

The atmospheric chemical kinetics of linear perfluorinated aldehyde hydrates, Cx-F2x+iCH(OH)2, have been measured for x = 1,3, and 4, focusing on formation (from aldehyde, by hydration), dehydration, and chlorine atom- and hydroxyl radical-initiated oxidation.211 The latter reaction is implicated as a significant source of perfluorinated carboxylic acids in the environment. 

An extension of the Erlenmeyer synthesis is the condensation of acylamino acids with triethyl orthoformate which leads to the ethoxymethylene derivatives (297). These can be hydrolyzed to the corresponding enols, which in turn can be converted into chloromethylene compounds, e.g. (298). The lability of the chlorine atom in this compound (see arrows) can be put to good account reaction with organometallic compounds or with benzene and its derivatives under Friedel-Crafts conditions yields unsaturated lactones (298 aryl or heteroaryl in place of Cl). The method is especially valuable in cases where the aldehyde is not readily available. 

The chlorine atom of chloromethyl derivatives of selenophene is very reactive and easily displaced in substitution reactions. Thus, 2-chloromethylselenophene and its homologs readily exchange the chlorine for dialkylamino, alkoxy, and acetoxy groups, and the chloromethyl can be converted into an aldehyde group, providing a synthesis for 2,5-dimethylselenophene-3-aldehyde (7) which cannot be obtained by direct formylation.102... 

Uns3mimetrical Di-chlor Ethane.—These two compounds may also be prepared by other reactions which show us what their true constitution is. When acet-aldehyde, which we have previously proven has the constitution represented by the formula, CH3—CHO, is treated with phosphorus penta-chloride one oxygen atom is replaced by two chlorine atoms and the product is one of the two isomeric di-chlor ethanes. 

This reaction is entirely different from that of phosphorus penta-chloride on alcohol, in which the hydroxyl of the alcohol is replaced by one chlorine, and the mono-halogen substitution product of the hydrocarbon results (p. 81). If our ideas in regard to the constitution of aldehyde are correct, this reaction must mean, that, in the di-chlor ethane formed in this way, the two chlorine atoms are linked to the same carbon atom. Such a structure represents a compound which is plainly unsymmetricaL... 

The overall reaction is called chloromethylation. However, the first step is hydroxyalkylation due to the reaction of the aldehyde with the benzene ring, and this is then followed by the acid catalysed substitution reaction of the hydroxyl group by the chlorine atom. Write down the steps in this reaction sequence, and so identify the role played by the Lewis acid. 

Schiff base formation in the Busch reaction may be avoided by employing N-( 1 -chlorobenzyl)benzimidoyl chloride, in which the aldehyde one-carbon fragment is already incorporated into the N-(l-chlorobenzyl) moiety both chlorine atoms participate in the reaction with arylhydrazine, to give modest yields of a A3-l,2,4-triazoline (Scheme 5) (79ZOR1181). 

Only two reactions involving the replacement of substituents at position 5 of 3,4-dihydro-2H-l,4-thiazines have been described. Thus, in the presence of sodium ethoxide, the chlorine atom of the derivative 56 was replaced by an ethoxy group, and, when heated at 140°-150°C, compound I64a underwent decarboxylation to give I64b. There are a number of examples in which modification of the S-substituent occurs. For example, when treated with lithium aluminum hydride, the acid 164a was reduced to the aldehyde 164c. ... 

Not only the a-polyhalogen aldehydes, but also the oc-polyhalogen ketones give the Perkow reaction with trialkyl phosphites, whereby vinyl phosphates are formed containing one chlorine atom less. In the reaction of triethyl phosphite with dichloromethyl-2,4-dichlorophenylketone, 0,0-diethyl-0-[l-(2,4-dichlorophenyl)-... 

Various 2-oxo compounds have been subjected to a variety of reactions. Alkylation and acylation result in the formation of 1,3-disubstituted products.Similarly the Mannich reaction with morpholine gives products such as the bis compound 107. Halogenation of the 0x0 compound 108 with bromine in acetic acid," or chlorine in acetic acid, ° or with sulfuryl chloride results in formation of the monohalo derivatives 109. The chlorine atom in 109 (R = Cl) can be removed by hydrogenation over palladium on charcoal. Nitration of the chloro compound 110 with a mixture of nitric and sulfuric acids provides the nitro derivative 111, which may be catalytically reduced to the amino compound 112. If the reduction is carried out in the presence of an aldehyde, the product is a substituted amino derivative (113). Alternatively the amine 112 can be condensed with an aldehyde and the resultant Schiff base reduced to give the product 113. 

A new synthesis of racemic oleuropeic acid (216) starts with the known Diels-Alder reaction between methyl vinyl ketone and chloroprene, yielding the chloro-ketone (217). The acid function is introduced by exchanging the chlorine atom for lithium, followed by conversion into the aldehyde with dimethylformamide, and the additional methyl group is put in with a Grignard reaction (Scheme 16). ... 

The electron-accepting properties of the chlorine atom at the polychloro-prene double bond reduces the reactivity of Denka M40 as demonstrated by its relatively low rate constant, i.e., k = A 10 M s In this reaction the ratio between the zwitterions A and B, according to theoretical calculations, is in favor of A, the ratio being AIB = 4.55. The A formation is accompanied by choroanhydryde group formation and that of B with aldehyde one. In both cases the ozonides formation is insignificant and the... 

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