stream Physical Properties: The polar nature of both the O-H and C=O bonds (due to the electonegativity difference of the atoms) results in the formation of strong hydrogen bonds with other carboxylic acid molecules or other H-bonding systems (e.g. α-Germyl nitriles may similarly be deprotonated with LDA, although α-lithiotrimethylgermylacetonitrile was found to be unstable even at −78 °C in ether (Equation (42)) <87SC1273>. Preparations of α-alkylated sulfides by direct deprotonation with BunLi or ButOK in THF at −40 °C has been developed for thiolane and thiane and their reactions with Sn- and Si-containing electrophiles and benzaldehyde; alkyl methyl sulfides were regioselectively deprotonated at the methyl group <1997TL8615>. The Mechanism of Acid-Catalyzed Nitrile Hydrolysis . Chantu R. Saha-MöllerWaldemar Adam, in Comprehensive Heterocyclic Chemistry II, 1996. For example, the reaction of t-butyl-β-chlorohydroperoxide (24) with sodium hydroxide in aqueous methanol afforded the 2-methylpropane-1,2-diol (Scheme 48). Deprotonation α to a single S requires a strong base; further functionalization of sulfides by C or heteroatom electrophiles occurs <1995COFGT(2)113>. Recently, the first phosphothiolate-mercaptophosphonate [1,2]-sigmatropic rearrangement was reported via α-deprotonation of a phosphorothiolate (Scheme 56) <1998T1523>. Table 7. J. Hill, in Comprehensive Heterocyclic Chemistry, 1984. Stabilisation of an anion α to the germyl group by an aryl group also enables easy deprotonation; for example, the preparation of (319) with t-butyllithium <87JA4411, 91MI 414-01>. The enolate can then react with a variety of electrophiles including deuterium oxide, methyl iodide, and aldehydes <1982T3059>. Thus α-germyl enolates have been readily generated by treatment of either an α-germyl ester <91JOC347> or ketone <87OM2568> with LDA. Deprotonation of ethynyl derivatives, generally to form the magnesium derivative, permits efficient condensation with aldehydes and ketones, for example, to yield the hydroxyalkyl compounds. Copyright © 2020 Elsevier B.V. or its licensors or contributors. x��ZMs#���W 7��¢��W�rH����$��\|�*T� )S���g��L��P�ݕH���n�k�������$���J��C-��r����������^B������h߁o�h�x�-�}��OR+cS�����R��[ \JHWm��;^I��� �~#�}J�s����%��-�rO�d�x��'��\�K��H�H�5�t�c���6�� The metal carbonyl complex formed by reaction of tri(phenylethynyl) antimony with dicobaltoctacarbonyl as described in the arsine case, has been fully characterised, but the interesting dimer (1) could not be obtained for the antimony case. These compounds were found to be excellent C-ligands for transition metals. The carboxyl carbon of the carboxylic acid is protonated. An example of α-alkylation of ethylthiomethyl acetate with methallyl bromide in the presence of LDA has been reported (68% yield) <2001JOC7270>. Many systems that are not readily generated by deprotonation have been generated by halogen–lithium exchange. This transformation was mechanistically rationalized in terms of deprotonation by sodium hydroxide of the intermediate dioxetane with concomitant OO bond cleavage to form α-hydroxyisobutyraldehyde. Examination of reaction field and reaction rate suggested that the deprotonation of thiepine 135b and subsequent alkylation took place on the surface of potassium carbonate, and the rate-determining step for the reaction was found to be the deprotonation (Equation 19) <2003MI727>. Deprotonation occurs selectively alpha to a carbanion-stabilizing substituent to provide benzyl, allyl, propargyl, and thiophenyl stabilized anions. Thus trimethylgermylmethyllithium was prepared from (chloromethyl) trimethylgermane and lithium dispersion or s-butyllithium <80JA1584>. Important examples include the amino acids and fatty acids.Deprotonation of a carboxylic acid gives a carboxylate anion Thus, amines 〈75JA5028, 75TL1735〉 and sodium hydroxide 〈71JA3996〉 convert such dioxetanes by the so-called Kornblum–De La Mare reaction 〈51JA880〉 into α-hydroxy carbonyl products. F. Couty, G. Evano, in Comprehensive Heterocyclic Chemistry III, 2008. 22.4) Rate= k [ketone/aldehyde] [H+] rate dependent on enol formation 233 α,β-unsaturated ketones and aldehydes: α -bromination followed by elimination O Br2, CH 3CO2 H Br O (C)O-K+ E2 CH3 CH3 CH3 O CH 3 OH H OH CH Why is one enol favored over the other? Deprotonation [carboxylate formation] Deprotonation [carboxylate formation] Definition: When treated with base, carboxylic acids form carboxylate salts. The reaction with several aryl halides under similar conditions gave the corresponding diarylacetic acids.