AZIRINE

1. AZIRINE One of the simplest heterocyclic compound or azacyclo propene. It could have structure 1 or II Azirine found natmaly as a part of some compound such as III and IV Which are used as an antibiotic and could be synthesis. Which are used as an antibiotic and could be synthesis. lec12

2. Reactions:- • Methanol reacted by addition with 1- azririne to give 2- Methoxy azirine in presence of sodmethoxide as a catalyst. • 3,3 – dimethyl -2- phynyl -1- azirine react with sulphonic acid. lec12

3. Reaction with acetic acid and acetic anhydride. • Reaction with Grignard reagent. lec12

4. Synthesis:- • From thermal analysis of Ethanyl azide which can be prepared from alkenes. lec12

5. Oxirane Oxirane or ethylene oxide (1) it was first obtain by wartz in 1859. in 1931 P taent was taken out on direct oxidation of ethylene to okirane by oxygen. Oxiranes found naturally in a plant, animal and insect. Orapetene (2) was oxirane separated from natural source. In general orxirane ring found as a part of structure of many compound specially prostalandine. Some oxirane drevative use as an antibiotic and its effective in treatment of malignant toummer. - It is colourless liquide misible with water lec12

6. Chemical properties:- 1. When oxirane heated its rearranged to aldehyde. 2.Ring opening:- The most important reaction of oxirane is the ring opening became its very important in organic synthesis. lec12

7. 3. Nucleophillic reagent:- It react with oxirane such as ammonia to give mono ethanolamine in excess of oxirane it give diethanol amine and triethanol amine. b - With Grignard reagent it give alcohol lec12

8. c – with halogen in presence of ph3p or lix give B- halo alcohol lec12

9. Reduction • Oxirane reduce to alcohol يراجع الترتيب lec12

10. Electrophillic reactions:- • Polymarisation:- lec12

11. Synthesis:- • 1. From B- Halo alcohol by elimination of hydrogen halide by base 2.Darzen reaction:- halo ester with carbonyl compound in presence of sod. Ethoxide. lec12

12. Thirane It is known also as ethylene sulphide its highly strain ring less stable than oxirane. Substituted thirane more stable than un-substituted one. It is colourless liquid in sulible in water but dissolve in organic solvent, boil at 55Co Chemical reactions:- 1. it react with ammonia to give drevative of B- aminothiol lec12

13. 2.Nucleophilic reagent always attack carbon atom but in thirane it attack carbon atom but in thirane it attack the sulphur atom leading to alkene formation. 3. It react with sodium periodate to give thirane okide. lec12

14. 4. Reduction This became the proton added to sulphur and carbonium ion formed. lec12

15. Synthesis: -1- 1. From chlorothiol cyclised by sod. Bicarbonate 2. From okirane when treated with pot. Thiocyanate. lec12

16. Heterocyclic analogues of cyclobutane Four membered ring are not highly strained as the corresponding three-membered rings. But are more difficult to prepare by the direct cyclisation of straight chain intermediate. The most important of four membered ring are Azetidine, oxetane and thietane. Oxetanes:- Synthesis By cyclo addition of two double bond. lec12

17. Reaction They are susceptible to acid catalyzed ring-opening reaction (like three membered ring analogues. It react with nucleophilic reagent but are less reactive than the analogues three membered ring compounds. lec12

18. Azetidine Synthesis:- Similar to oxetanes preparation lec12

19. Thietanes Syntesis:- By ring closure similar to azetidine lec12