* In Clemmensen reduction, the amalgamated zinc in HCl is used as reducing agent. Clemmensen reduction is complementary to Wolff-Kishner reduction, which also converts aldehydes and ketones to hydrocarbons, in that the former is carried out in strongly acidic conditions and the latter in strongly basic conditions. Both these processes do these conversions via reducing the functional groups. This reaction is named after Erik Christian Clemmensen, a Danish chemist. reduction, which However, the corresponding alcohol is believed not to be an intermediate, since subjection of the alcohol to Clemmensen conditions generally does not afford the alkane product. The Wolff–Kishner reduction is a reaction used in organic chemistry to convert carbonyl functionalities into methylene groups.In the context of complex molecule synthesis, it is most frequently employed to remove a carbonyl group after it has served its synthetic purpose of … Mitteilung. * The Clemmensen reduction is complementary to Wolff-Kishner * The C=O group is converted to CH2 group. Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. )", "Modified Clemmensen Reduction: Cholestane", https://en.wikipedia.org/w/index.php?title=Clemmensen_reduction&oldid=960785662, Creative Commons Attribution-ShareAlike License, This page was last edited on 4 June 2020, at 22:12. Ans: Nucleophilic substitution is not easy on sp2 carbon of benzene ring! This is an example of  : (KERALA SET 2010). The Clemmensen reduction may be fine for the laboratory, but fundamentally many industries wouldn't use it due to scaling up the use of mercury. [8][9] Mechanistic proposals generally invoke organozinc intermediates, sometimes including zinc carbenoids, either as discrete species or as organic fragments bound to the zinc metal surface. Watch the recordings here on Youtube! Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. Several alternatives are available. [1][2][3] This reaction is named after Erik Christian Clemmensen, a Danish chemist. this side reaction can be avoided by employing Wolff-Kishner Clemmensen reduction is a chemical reaction described as a reduction of ketones (or aldehydes) to alkanes using zinc amalgam and concentrated hydrochloric acid. may be used to reduce acid sensitive compounds. This reaction done with zinc amalgam and hydrochloric acid and it is generally known as Clemmensen reduction. The Clemmensen reduction of 2-acetylfluorene may proceed through the corresponding carbinol, 2-(α-hydroxyethyl)fluorene, to the normal reduction product, 2-ethylfluorene. (Why? A new experimental protocol has been established for the Clemmensen reduction of diosgenin and kryptogenin with the aim to prepare deuterated isotopomers of (25R)-26-hydroxycholesterol. * As there is no formation of alcohol during the reaction, this method is not useful to reduce alcohols to alkanes. to alkanes. * In Clemmensen reduction, the amalgamated zinc in HCl is used as reducing agent. Acid-sensitive substrates that are stable to strong base can be reduced using the Wolff-Kishner reduction; a further, milder method for substrates stable to hydrogenolysis in the presence of Raney nickel is the two-step Mozingo reduction. (III. * The Clemmensen reduction occurs over the surface of zinc catalyst. Therefore, these processes … method. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. CLEMMENSEN REDUCTION :- useful for CSIR NET JRF, GATE, SET, IIT JEE, IIT JAM, NEET, UPSC, GEO-Chemistry, UPSC Optional. … Clemmensen reduction is a chemical reaction described as a reduction of ketones (or aldehydes) to alkanes using zinc amalgam and concentrated hydrochloric acid. It is the reduction of carbonyl groups ( in aldehyde and ketone) to methylene group. [10], "Reduktion von Ketonen und Aldehyden zu den entsprechenden Kohlenwasserstoffen unter Anwendung von amalgamiertem Zink und Salzsäure", "Über eine allgemeine Methode zur Reduktion der Carbonylgruppe in Aldehyden und Ketonen zur Methylengruppe", "Über eine allgemeine Methode zur Reduktion der Carbonylgruppe in Aldehyden und Ketonen zur Methylengruppe. In spite of the antiquity of this reaction, the mechanism of the Clemmensen reduction remains obscure. Due to the heterogeneous nature of the reaction, mechanistic studies are difficult, and only a handful of studies have been disclosed. * The Clemmensen reduction is complementary to Wolff-Kishner reduction, which may be used to reduce acid sensitive compounds. INTRODUCTION This reaction was first reported by Clemmensen of Park Davis in 1913. The reaction of aldehydes and ketones with zinc amalgam (Zn/Hg alloy) in concentrated hydrochloric acid, which reduces the aldehyde or ketone to a hydrocarbon, is called Clemmensen reduction. 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