Carboxylic acids, reaction with thionyl chloride

Carboxylic acids react with thionyl chloride to form acid chlorides. Reaction with alcohols gives esters, and with amines, amides are formed. 

The immobilization procednre involved the acid oxidation of the parent ACs and CNTs, reaction of the carboxylic acid groups with thionyl chloride to give the acyl chloride groups, which were finally reacted with the spacer... 

Carboxylic acids react with thionyl chloride (SOQ2) to produce the corresponding add chlorides, as shown in the above reaction.Thionyl chloride is an attractive reagent due to its low cost, and the fact that both byproducts produced in the reaction are gases. Thus, the reaction is driven to completion by the evolution of HCl and SO2, and a nearly pure acid chloride is obtained. The major drawback to the reaction is that it produces a strong acid (HCl) and thus cannot be used with compounds that are acid sensitive. Oxalyl chloride is often used as an alternative reagent. 

Thiazete ring systems have also been proposed as being intermediates in the reaction of guanidines with carbon disulphide and in the reaction of carboxylic acid amides with thionyl chloride and pyridine. ... 

Acyl chlorides are readily available They are prepared from carboxylic acids by reaction with thionyl chloride... 

The 3-o-ch orophenvl-5-methvlisoxa2ole4-carboxylic acid, from which the acid chloride was prepared, was obtained by hydrolysis of the ester product of the reaction between o-chloro-benzohydroxamic chlorideand ethyl acetoacetate in methanolic sodium methoxide. Reaction with thionyl chloride gave the starting material. 

Acid chlorides are prepared from carboxylic acids by reaction with thionyl chloride (SOCl2), as we saw in the previous section. Similar reaction of a carboxylic acid with phosphorus tribromide (PB ) yields the acid bromide. 

PLLA-fr-PCL) multiblock copolymers were prepared from the coupling reaction between the bischloroformates of carboxylated PLLA with diol-terminated PCL in the presence of pyridine [140]. LLA was polymerized with SnOCt2 and 1,6-hexanediol followed by the reaction with succinic anhydride to provide the dicarboxylated PLLA. The carboxyl end groups were subsequently transformed to acid chloride groups by the reaction with thionyl chloride (Scheme 65). As expected, the molecular weight distributions were broad for all samples (1.84 < Mw/Mn < 3.17). 

The synthesis of the corresponding naphthyridone scaffold was carried out according to the methods reported by Chu et al. [12] and Sanchez et al. [13]. Namely, the hydrolysis of ethyl 2,6-dichloro-5-fluoronicotinate (3) [14] followed by reaction with thionyl chloride results in the formation of 2,6-dichloro-5-fluoronicotinyl chloride (4). Treatment of this compound with monoethyl malonate in THF under n-butyllithium followed by acidification and decarboxylation gives rise to ethyl 2,6-dichloro-5-fluoronicotinylacetate (5). Reaction of compound 5 with ethyl orthoformate in acetic acid followed by cyclopropylamine results in the formation of 3-cyclopropylamino-2-(2,6-dichloro-5-fluoronicotinyl)acrylate (6), the cyclization reaction of which under NaH/THF gives rise to the required ethyl l-cyclopropyl-6-fluoro-7-chloro-l,4-dihydro-4-oxo-l,8-naphthyridine-3-carboxylate (7), as shown in Scheme 3. 

Information concerning the position of the carboxyl groups relative to each other was obtained from the neutralization behavior after reaction with thionyl chloride 35, 47). More base ought to be consumed by such products because additional alkali is used for the neutralization of the hydrochloric acid liberated on hydrolysis. As is shown in Table VII, the additional alkali consumption was equivalent to the quantity of chloride ions found in the solution. However with all the samples which had been activated with carbon dioxide, less sodium ethoxide was consumed than had been expected. The deficit was equivalent to half the NaHCOj neutralization value. This strange behavior can be explained only by... 

The synthesis of a triptan with a chiral side chain begins by reduction of the carboxylic acid in chiral 4-nitrophenylalanine (15-1). The two-step procedure involves conversion of the acid to its ester by the acid chloride by successive reaction with thionyl chloride and then methanol. Treatment of the ester with sodium borohy-dride then afford the alanilol (15-2). Reaction of this last intermediate with phosgene closes the ring to afford the oxazolidone (15-3) the nitro group is then reduced to the aniline (15-4). The newly obtained amine is then converted to the hydrazine (15-5). Reaction of this product with the acetal from 3-chloropropionaldehyde followed by treatment of the hydrazone with acid affords the indole (15-6). The terminal halogen on the side chain is then replaced by an amine by successive displacement by means of sodium azide followed by catalytic reduction of the azide. The newly formed amine is then methylated by reductive alkylation with formaldehyde in the presence of sodium cyanoborohydride to afford zolmitriptan (15-7) [15]. 

Acid chlorides are prepared from the corresponding carboxylic acids, most commonly from the reaction with thionyl chloride or oxalyl chloride (see Section 5.5.5). 

Acid esters are useful synthetic intermediates. For example, their use in the synthesis of long-chain dicarboxylic esters by electrolytic (anodic) synthesis has already been noted (Expt 5.131). Furthermore the reaction of the acid ester with thionyl chloride in the usual way will convert the carboxylic acid grouping to an acyl chloride group thus yielding the synthetically useful ester-acyl chloride the products are usually purified by distillation under reduced pressure. 

In the event, iodolactonization of the carboxylate salt derived from the ester 458 afforded 459, and subsequent warming of the iodo lactone 459 with aqueous alkali generated an intermediate epoxy acid salt, which suffered sequential nucleophilic opening of the epoxide moiety followed by relactonization on treatment with methanol and boron trifluoride to deliver the methoxy lactone 460. Saponification of the lactone function in 460 followed by esterification of the resulting carboxylate salt with p-bromophenacylbromide in DMF and subsequent mesylation with methanesulfonyl chloride in pyridine provided 461. The diazoketone 462 was prepared from 461 by careful saponification of the ester moiety using powdered potassium hydroxide in THF followed by reaction with thionyl chloride and then excess diazomethane. Completion of the D ring by cyclization of 462 to the keto lactam 463 occurred spontaneously on treatment of 462 with dry hydrogen chloride. 

For the formation of carboxylic acid chlorides from carboxylic acids different procedures are known. Often thionyl chloride or oxalyl chloride, both with catalytic amounts of DMF, are used. The reaction with thionyl chloride requires elevated temperatures and often provides various byproducts. Oxalyl chloride is useable at room temperature or... 

By using a multistep procedure, DNA molecules have been covalently attached to SWNTs. First, the purified SWNTs were oxidized to form carboxylic acid groups at the ends and sidewalls, followed by reaction with thionyl chloride and ethylenediamine to produce amine-terminated sites. The amines were then reacted with the heterobifunctional cross-linker succinimi-dyl 4-(iV-maleimidomethyl)cyclohexane-l-carboxylate (SMCC), leaving the surface terminated with maleimide groups. Finally, thiol-terminated DNA reacted with these groups to produce DNA-modified SWNTs [161]. AAHien DNA is covalently attached to SWNTs, a better stability, accessibility and selectivity are expected during competitive hybridization. 

Surface oxides on graphite undergo the reactions typical of carboxylic acids, phenols and alcohols. Methylation with diazomethane or dimethylsulfate, silanization of—OH groups by reaction with halosilanes, formation of acyl chlorides by reaction with thionyl chloride, further reactions of these acyl chlorides, neutralization of acidic surface groups with different bases, ion exchange and more special reactions are used to characterize surface oxides on carbon and to modify their properties for technical applications . 

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