The Hunsdiecker reaction (also called the Borodin reaction or the Hunsdiecker–Borodin reaction ) is a name reaction in organic chemistry whereby silver salts of carboxylic acids react with a halogen to produce an organic halide . It is an example of both a decarboxylation and a halogenation reaction as the product has one fewer carbon atoms than the starting material (lost as carbon dioxide ) and a halogen atom is introduced its place. A catalytic approach has been developed.
12-410: The reaction is named after Cläre Hunsdiecker and her husband Heinz Hunsdiecker , whose work in the 1930s developed it into a general method. The reaction was first demonstrated by Alexander Borodin in 1861 in his reports of the preparation of methyl bromide ( CH 3 Br ) from silver acetate ( CH 3 CO 2 Ag ). Three decades later, Angelo Simonini, working as a student of Adolf Lieben at
24-413: A green metal-free reaction, tetrabutylammonium trifluoroacetate serves as an alternative catalyst. However, it only exhibits comparable yields to the original lithium acetate when performed with micellular surfactants . Cl%C3%A4re Hunsdiecker Cläre Hunsdiecker ( née Dieckmann ) (1903–1995) was a German chemist who worked with her husband Heinz Hunsdiecker (1904–1981) to improve
36-447: A German chemist is a stub . You can help Misplaced Pages by expanding it . Micellar solubilization Micellar solubilization ( solubilization ) is the process of incorporating the solubilizate (the component that undergoes solubilization) into or onto micelles . Solubilization may occur in a system consisting of a solvent , an association colloid (a colloid that forms micelles), and at least one other solubilizate. Solubilization
48-538: A reaction of Alexander Borodin now known as the Hunsdiecker reaction . They received both US and German patents for the work. Hunsdiecker earned her Ph.D. from the University of Cologne . For many years, it was believed that there was no photographic image of Hunsdiecker in existence. In 2020, an image was located by an undergraduate student at the University of Melbourne . This article about
60-407: Is distinct from dissolution because the resulting fluid is a colloidal dispersion involving an association colloid. This suspension is distinct from a true solution , and the amount of the solubilizate in the micellar system can be different (often higher) than the regular solubility of the solubilizate in the solvent. In non-chemical literature and in everyday language, the term "solubilization"
72-466: Is known as Cristol-Firth modification. The 1,3-dihalocyclobutanes were key precursors to propellanes . The reaction has been applied to the preparation of ω-bromo esters with chain lengths between five and seventeen carbon atoms, with the preparation of methyl 5-bromovalerate published in Organic Syntheses as an exemplar. For unsaturated conmpounds, the radical conditions associated with
84-513: Is sometimes used in a broader meaning as "to bring to a solution or (non- sedimenting ) suspension" by any means, e.g., leaching by a reaction with an acid. Micellar solubilization is widely utilized, e.g. in laundry washing using detergents , in the pharmaceutical industry, for formulations of poorly soluble drugs in solution form, and in cleanup of oil spills using dispersants . Literature distinguishes two major mechanisms of solubilization process of oil by surfactant micelles, affecting
96-553: The University of Vienna , investigated the reactions of silver carboxylates with iodine . He found that the products formed are determined by the stoichiometry within the reaction mixture. Using a carboxylate-to-iodine ratio of 1:1 leads to an alkyl iodide product, in line with Borodin's findings and the modern understanding of the Hunsdiecker reaction. However, a 2:1 ratio favours the formation of an ester product that arises from decarboxylation of one carboxylate and coupling
108-655: The alkali metals , have only rarely led to reported success. The Kochi reaction is a variation on the Hunsdiecker reaction developed by Jay Kochi that uses lead(IV) acetate and lithium chloride ( lithium bromide can also be used) to effect the halogenation and decarboxylation. In the presence of multiple bonds , the intermediate acetyl hypohalite prefers to add to the bond, producing an α-haloester. Steric considerations suppress this tendency in α,β-unsaturated carboxylic acids, which instead polymerize (see below). Mercuric oxide and bromine convert 3-chlorocyclobutanecarboxylic acid to 1-bromo-3-chlorocyclobutane. This
120-488: The Hunsdiecker reaction can also induce polymerization instead of decarboxylation. Consequently, reactions with α,β-unsaturated carboxylic acids typically give low yield. Kuang et al have found that an alternate radical halogenating agent, N-halosuccinimide, combined with a lithium acetate catalyst, gives a higher yield of β-halostyrenes. The reaction also improves in the presence of microwave irradiation , which preferentially synthesizes ( E )-β-arylvinyl halides. For
132-612: The acyl hypohalite intermediate 2 . Formation of the diradical pair 3 allows for radical decarboxylation to form the diradical pair 4 , which recombines to form the organic halide 5 . The trend in the yield of the resulting halide is primary > secondary > tertiary. The reaction cannot be performed in protic solvents , as these induce decomposition of the intermediate acetyl hypohalite . Other counterions than silver typically have slow reaction rates. The toxic relativistic metals ( mercury , thallium , and lead ) are preferred: inert counterions, such as
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#1732776674217144-474: The resulting alkyl chain with the other. Using a 3:2 ratio of reactants leads to the formation of a 1:1 mixture of both products. These processes are sometimes known as the Simonini reaction rather than as modifications of the Hunsdiecker reaction. In terms of reaction mechanism , the Hunsdiecker reaction is believed to involve organic radical intermediates. The silver salt 1 reacts with bromine to form
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