During Clemmensen’s reductions, both aldehydes and ketones lose their carbonyl groups, and thus lose an oxygen atom. 3) In the following reaction, along with the reduction of carbonyl group, the -OH group is substituted by the -Cl group (side reaction). endobj ), 1) Acetophenone when reacted with Zn (Hg) and HCl in ethyl alcohol �#� Clemmensen reduction and its products of some aldehydes and ketones are explained below. Dadurch bildet sich eine Sauerstoff-Zink-Bindung aus und gleichzeitig entsteht ein Kohlenstoff-Radikal-Anion. Aldehydes, and ketones can be reduced to alcohols, and even further reduced to methylene groups. It has been reported that alcohol is not the intermediate of the Clemmensen reduction and carbonium is involved in this reduction. <>stream Nach erneuter Protonierung und Elektronentransfer wird Wasser abgespalten und der Zink-Carben-Komplex gebildet. Der Mechanismus ist nicht abschließend gesichert. The Clemmensen Reduction removes a double-bonded oxygen from a carbon, and replaces it with two hydrogen atoms. endobj Several alternatives are available. Von den Atomen zu Molekülen - Atombindung, Halogene - Alkalimetalle - Redoxreaktionen, 38. endstream Mitteilung. 1998-07-15T11:28:28Z2020-11-25T06:01:38-08:00Adobe PageMaker 6.5 Clemmensen reduction of ethanal. * The Clemmensen reduction is used to conveniently reduce the carbonyl compounds, which are stable to strongly acidic conditions, 4) But the phenol group is not affected in Clemmensen reduction. The Clemmensen reduction generally converts carbonyl group into methylene group, but some abnormal reactions have also been reported to occur. '�>�0��N����稙c0\��T���p"1U��AC���s��� St�@;$`_9�� ��v)�B����e��μ�O�db�CS�S��tC�B��b(���1�-Ÿ�mo��I�n�x‘ۂ3�YU�[���z����&. Als Substrate dienen Aldehyde, aliphatische Ketone und araliphatische Ketone (mit einem aliphatischen und einem aromatischen Rest), wobei Diarylketone im Allgemeinen schlecht reagieren [2] alcohols are ultimately deoxygenated to hydrocarbons is strange and, to some people, perhaps, may even be quite con-fusing. Due to the heterogeneous nature of the reaction, mechanistic studies are difficult, and only a handful of studies have been disclosed. <>>>/BBox[0 0 585 783]/Length 45>>stream (III. It has been reported that alcohol is not the intermediate of the Clemmensen reduction and carbonium is involved in this reduction. endobj In beiden Fällen wird (hier nicht dargestellt) die entsprechende Menge Zink in Form von Zinkchlorid freigesetzt. 13 0 obj Organic compounds are found all around us and form the essential substances used in daily life. endobj endobj endobj Die Clemmensen-Reduktion ist eine Reaktion aus dem Bereich der Organischen Chemie. Mechanismus 2: Clemmensen Reduction acid alcohol aldehyde alkane acid alkane (–1C) CH3 Samarium Iodide Ionic Hydrogenation (Et3SiH, TFA) Luche Reduction (NaBH4, CeCl3) ** 1. ��w3T�PI�2T0 BC#K#=SC#��\. Learn about our remote access options. Advanced Organic Chemistry, 4th ed. ͐,.�. 6 0 obj The Clemmensen reduction is named after a Danish chemist, Erik Christian Clemmensen. Dann wird wie oben durch Protonierung und Elektronentransfer der Kohlenwasserstoff freigesetzt. With aliphatic or cyclic ketones, modified Clemmensen conditions using activated zinc dust in an anhydrous solution of hydrogen chloride in diethyl ether or acetic anhydride is much more effective.[7]. 12 0 obj <>stream [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. Durch zweimalige Protonierung und zweimaligen Elektronentransfer wird der Kohlenwasserstoff freigesetzt. Line: 208 endstream x��1� D{N���I-���0��� d�do/4��ݷ7��c���3�4LNjn�ux!Ժ�՘m�v��\��� VoR x�S�*�*T0T0 B�����i�����U���n)c�T �h� Durch die Säure wird der Sauerstoff der Carbonylgruppe protoniert.

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