presentation on norrish type 1 and norrish type 2

chem

1. G.H. Raisoni University DhodaBorgaon, vil.saikheda, M.P. NORRISH TYPE 1 and 2 REACTIONS PRESENTED BY: BHUMIKA G. CHAOUDHARY M.SC 3 rd semester Department of chemistry Guided by : Yashna H. Pahwa

2. Introduction to Norrish type 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 Norrish reaction. 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 1 reaction “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: Norrish type 1 is highly efficient for vapour and gaseous state molecule. If compound is able to produce stable radical intermediate then even in solution state it can undergo norrish type 1.

5. Norrish type 1 reaction mechanism

6. Norrish type 2 reaction 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: 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

7. Norrish type 2 mechanism

8. guided by : yashna pahawa mam

9. Thank you