Ccccfuran.pptx Muhammad safwan1234567890

Presentation

1. Furan ( oxoline ): Furan: is a heterocyclic organic compound, consisting of a five- membered aromatic ring with four carbon atoms and one oxygen. Furan was first prepared by  Heinrich Limpricht  in 1870 , although he called it "tetra phenol”. Structure:- All ringed atoms in furan are sp 2 hybridized and the π -electrons are delocalized into the ring, giving it the characteristic of aromaticity. The name "furan" came from the Latin word  "furfur” which means bran(hard outer layer of cereal grain). The first furan derivative to be discovered was 2-furoic acid, by  Carl Wilhelm Scheele  in 1780. 1 Furan

2. Resonance and Aromaticity in Furan: Furan is aromatic because one of the lone pairs of electrons on the oxygen atom is delocalized into the ring. Because of the aromaticity , the molecule is flat and lacks discrete double bonds. The other lone pair of electrons of the oxygen atom extends in the plane of the flat ring system. The sp 2 hybridization is to allow one of the lone pairs of oxygen to reside in a p orbital and thus allow it to interact within the π system . 2

3. Physical Properties: Chemical formula of furan is C 4 H 4 O. Molar mass of furan is 68.08 g/mole. Density of furan is 0.936 g/ml or 936 kg/m 3 . It is a colorless, flammable and highly volatile liquid. Boiling point is close to room temperature about 31.3 o C. It is soluble in common organic solvents such as alcohol , ether and acetone . It is slightly soluble in water . 3

4. 4 It is toxic and may be carcinogenic in humans. It is used as a starting point to many other specialty chemicals (chemicals which provide materials on which many industrial sectors rely. e.g. adhesives, agrochemicals, cleaning materials and cosmetics etc).

5. Methods of preparation of Furan [1]. Paal-Knorr synthesis: This is the reaction that generates either furans, pyrroles, or thiophenes from 1,4-dicarbonyl compounds thorough condensation reaction . It is a synthetically valuable method for obtaining substituted furans and pyrroles, common structural components of many natural products. 5

6. Mechanism : Example: 1,4 – Dicarbonyl compound such as acetonylacetone on heating with phosphorous pentaoxide (P 2 O 5 ) undergoes dehydration to form 2, 5-dimethylfuran. This reaction follows Paal-Knorr mechanism. 6

7. [2]. From Furfural: Furfural(a furan + aldehydic group) on oxidation gives furoic acid, which on heating decarboxylates to give furan. [3]. From Pentanosans : 7

8. 8 [4] From Mucic Acid : Dry distillation of mucic acid to form furoic acid and heating it up to its boiling point to perform its decarboxylation gives furan.

9. 9 [5]. From Barium Pyromucate: Furan occurs naturally in wood tar and in pine-wood distillate and therefore, it can also be obtained by the distillation of Barium pyromucate .

10. Chemical properties of Furan: 10 General overview of electrophillic substitution reactions

11. 11 [1]. Nitration: Nitration is done in the presence of fuming nitric acid and acetic anhydride at 10 o C tepmrature . [2]. Acetylation : : Furan reacts with organic compounds containing acetyl group (CH 3 CO-) such as acetic anhydride to form acetylated furans and requires a Lewis base such as BF 3 for its propagation.

12. 12 [3]. Mercuration : Furan when treated with mercurric chloride in the presence of aqueous sodium acetate to give 2-chloromercurric furan. [4]. Gomberg reaction: This reaction is basically the arylation of furan in the presence of diazonium salts in alkaline solution. furan 2-chloromercurric furan furan Arylated furan diazonium salt halogenation acetylation

13. 13 [5]. Halogenation : In this type of reaction halogen atom is introduced to furan ring in the presence of Dioxane (C 4 H 8 O 2 ) and temperature is maintained at O o C . [6]. Sulphonation : Furan is sulphonated at 100 o C, in the presence of fuming sulphuric acid and pyridine.

14. 14 [7]. Hydrogenation: Furan can be reduced to tetrahydrofuran by Raney Nickel. Raney nickel gives oxidation reactions with a high yield. Raney nickel Aluminum nickel alloy Caustic soda Raney nickel

15. 15 THF is a very important compound as a solvent, and forms adipic acid when reacted with CO 2 nd H 2 O. It forms pyrrolidiene with ammonia. And 4-chlorobutan-1-ol with HCL. 2

16. 16 furan 2-chlorofuran 2-bromofuran 2-nitrofuran 2-furansulphonic acid acetylated furan Summary of some reactions of Furan

17. For your concept: Furan gives electrophillic substitution reactions at position 2 because of the attainment of stability through resonance . An explanation for the general α-selectivity of these substitution reactions is apparent from the mechanism outlined below. The intermediate formed by electrophile attack at C-2 is stabilized by charge delocalization to a greater degree than the intermediate from C-3 attack. 17

18. Identification tests of Furan 18 Physical tests:- Flame test: Take 1-2ml of organic compound in a china dish and ignite it. Black, sooty smoke will be produced. Boiling point determination: Find the boiling point of the organic compound. Boiling point is found to be 31.1 o C.

19. 19 Chemical tests:- Test for checking aromatic nature of organic compound: Take 1ml of organic compound in a test tube and add 2ml of HNO 3 and 2ml of H 2 SO 4 to it. Heat the reaction mixture for 2-3 minutes and then cool it under tap water. Now add 5ml distilled water and gently shake the test tube. Yellow ppts confirm the presence of aromaticity in compound. Tests for checking unsaturation in organic compound: 1. Baeyer’s test: Take 2ml of organic compound in a test tube and add 2-3 drops of 1% alkaline KMnO 4 to it. Purple color of KMnO 4 is discharged. Aromatic nature Negative Positive

20. 20 2. Br 2 test: Take 1ml of organic compound in a test tube and add 2-3 drops of Br 2 water to it. Color of Bromine water discharged. negative positive

21. Pharmaceutical Applications of Furan: 21 [1]. Nitrofurans : are a class of drugs typically used as antibiotics or antimicrobials. The defining structural component is a furan ring with a nitro group. Anti-bacterial: Nitrofurazone also known as nitrovin (an antibacterial growth promoter used in animal feeds). Anti- protozoal : Furazidine (anti- bactrial and anti- protozoal ). nitrofurazone furazidine

22. 22 [2]. Ranitidine: is in a group of drugs called histamine-2 blockers. It works by reducing the amount of acid the human stomach produces. Ranitidine is used to treat and prevent ulcers in the stomach and intestines. It also treats conditions in which the stomach produces too much acid, such as Zollinger -Ellison syndrome . Ranitidine also treats gastro esophageal reflux disease (GERD) and other conditions in which acid backs up from the stomach into the esophagus, causing pyrosis (heart burn).

23. 23 [3]. Furfuryl thiol : It is commonly used as food additive. Naturally, it is found in wheat, bread and cooked meat. It smells like roasted coffee seeds. [4]. Vitamin C: Vitamin C is needed for healing wounds, and for repairing and maintaining bones and teeth. It is also an anti-oxidant and its deficiency causes rickets. Furfuryl thiol