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presentation on norrish type 1 and norrish type 2
- 1. G.H. Raisoni University DhodaBorgaon,vil.saikheda, M.P. NORRISH TYPE 1 and 2 REACTIONS PRESENTED BY: BHUMIKA G. CHAOUDHARY M.SC 3rd semester Department of chemistry Guided by : Yashna H. Pahwa
- 2. Contents: Introduction to Norrishtype 1 and type 2 reaction. Norrish type 1 reaction • Norrish type 1 mechanism Norrish type 2 reaction • Norrish type 2 mechanism Bibliography Acknowledgement
- 3. Introduction to Norrishreaction. • A Norrish reaction in organic chemistry is a photochemical reaction taking place with ketones and aldehydes. Such reactions are subdivided into Norrish type I reactions and Norrish type II reactions. • The reaction is named after Ronald George Wreyford Norrish. • While of limited synthetic utility these reactions are important in the photo-oxidation of polymers such as polyolefins, polyesters, certain polycarbonates and polyketones.
- 4. Norrish type 1reaction “Photochemical reaction of ketones and aldehyde of carbon- carbon double bond adjacent to carbonyl group with elimination of carbon monoxide is termed as norrish type 1 process or cleavage”. Characteristic of reaction: I. Norrish type 1 is highly efficient for vapour and gaseous state molecule. II. If compound is able to produce stable radical intermediate then even in solution state it can undergo norrish type 1.
- 5. • Norrish type1 reaction mechanism
- 8. Norrish type 2reaction Aldehyde and ketones containing one gamma hydrogen atom on irradiation undergoes fisson at alpha and beta bond to form olefins and kiton via enol formation . This reaction is called as norrish type 2 reaction”. Characteristic of reaction: I. Norrish type 2 reactions are observed for both aromatic and aliphatic ketons i.e. n pi *(s1) and n pi* (T1) state participate in intramolecule hydrogen absorption reaction while ketons with low lying pi –pi* state do not undergo this reaction
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- 11. guided by :yashna pahawa mam
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