Organic Synthesis Sterine, (S)-Phenyl-1-Propanol and 1, 4-Dyhydrobenzoic Acid - Assignment Example

ORGANIC SYNTHESIS OF STERINE, (S)-PHENYL PROPANOL AND 4-DYHYDROBENZOIC ACID by Physical address ORGANIC SYNTHESIS OF STERINE, (S)-PHENYL-1-PROPANOL AND 1, 4-DYHYDROBENZOIC ACID Abstract This report explores suitable and safe experimental procedures followed when conducting a synthesis of styrene, (S)-Phenyl-1-propanal and 1, 4-Dihydrobenzoic acid. It also discusses the apparatus used in the preparation of the mentioned organic compounds. However, only two special apparatus have been represented diagrammatically. This includes a reaction flask of low hydrogenation and a Schlenk tube used in the synthesis of styrene and phenyl-1-propanol respectively. Besides, the preparation of Lindlar catalyst has also been outlined together with safety measures taken when handling the reagents and apparatus. Introduction Organic synthesis involves the formation of organic compounds using chemical reactions. It involves transformation of simple molecules into target molecules (Starky 2012). Organic compounds have considerable uses in industrial sector thus their construction has developed from simple to complex processes. Synthesis of organic compounds takes two forms; total or methodology. In total synthesis a whole organic compound is formed from naturally available substances. It involves many procedures until a complete compound is constructed. In the process, a variety of compounds are formed which are called intermediates. Alternatively, methodology approach put more emphasis on the process that gives good yield. Therefore, The reactions are manipulated to meet quality checks. (S)-Phenyl-1-propanol is a liquid whose boiling point and density is 94.5oC and 0.99g/cm3 respectively. It is viscous and mixes with organic solvents like benzene and toluene but does not dissolve in water. It is mostly used to transfer heat in thermal systems. On safety front, the substance is not classified as dangerous, however, it can cause harmful effects when swallowed or come into contacts with parts of the body like eyes and skin. One of the methods of preparing it is reacting benzeldehyde with diethylzinc and (Dimethylamino)isoborneol. DAIB is strong electron oxidant used in many chemical reactions (Gladysz, Curran and Istavan 2004). 1, 4-dihydrobenzoic acid is formed through reduction of benzoic acid in sodium dissolved in ammonia by a process called birch reaction. Generally, when benzene having an electron donating substituent are reduced, 1,4-dihydro compounds are formed (Carruthers and Coldham 2004). Styrene or vinyl benzene is colourleess viscous liquid that is highly volatile. It is also a monomer used to produce polystyrene which has wide applications in plastic packaging (US Department of Health and Human services 2011). This makes the global production of styrene very high about 21million tones annually. Over 90% of industrial styrene is made by dehydrogenation of ethylbenze using catalyst. In the laboratory, styrene can be prepared by hydrogenation of phenylacetylene in presence of Lindlar catalyst. This catakyst ensures that only one functional group is hydrogenated without affecting the others. It involves syn addition of the hydrogen atom to C-C triple bond resulting into cis-alkene. (Brown et al 2012). Procedure for synthesis of styrene 1.4g of palladous chloride was placed in 15ml Erlenmeyer flask and 3.5ml of 37.2% hydrochloric acid added. The solution was warmed to 300C and shaken until the chloride salt dissolved. The solution was transferred to 250ml beaker already containing 45ml of distilled water. Sodium hydroxide was dropped from the burette into the solution and stirred to raise it to 4.3. The solution was diluted to about 100ml in graduated cylinder. It was then transferred to 250ml round bottom flask and placed in water with thermometer immersed in water. Precipitated calcium carbonate was added and the mixture was heated to 800C for 13minutes until palladium began to form solid. Maintaining the temperature at 800C, 6ml of sodium sulphate solution was added. There was a further addition of 4.5 sodium sulphate followed by stirring of the mixture for 35minutes at the same temperature until the catalyst turned black. The catalyst was separated using Buchner funnel and washed with 5 60ml portions of distilled water. The catalyst was then placed in 250ml round bottomed flask. 60ml of water and 18ml of 7.7% solution of lead acetate was added. The mixture was stirred and heated for 40minutes. The catalyst was then separated using Buchner funnel and washed with 5 60ml portion of distilled water. The catalyst was then dried in an oven at 650C. 2g of phenylacetylene, 10ml of quinoline, 1g of the catalyst and 15ml of olefin free petroleum ether was placed into a reaction flask of low hydrogenation apparatus. The apparatus was evacuated and hydrogen admitted into the apparatus at a pressure of 1 tm. Procedure for synthesis of 1,4-phenyl-1-propanol 1.8g[2S]-DAIB, 200ml of dry toluene, 25ml of 4.45M toluene solution of diethylzinc were introduced into argon filled Schlenk tube via a rubber septum using syringes at 200C. The mixture was stirred for 20minutes then cooled to -780C with dry ice methanol bath. 10g of benzaldehyde was added to the mixture. The methanol bath was replaced with ice bath and rubber septum replaced by glass stopper. The reaction was stired at 00C for 5hours. The glass stopper was removed under argon steam and 40ml of saturated aqueous ammonium chloride added. This leads to a formation of white precipitate. The liquid and solid phases were separated by decantation. The precipitate was washed by 100ml ether, and combined liquid layers plus 100ml of 2M hydrochloric acid was transferred to 1 litre separation funnel. The aqueous layer was extracted with ether. The organic layer was washed with 50ml of water and 50ml of brine and dried over anhydrous sodium sulphate and concentrated under low pressure. The crude residue was distilled at 1500C under pressure of 20mm HG using Kugelrohr apparatus to give phenypropanol. Procedure for synthesis of 1,4-dihydrobenzoic acid To 100ml of anhydrous ethanol in flask 10 grams benzoic acid was added. After benzoic acid had dissolved, 600ml of liquid ammonia was poured into the flask and the mixture stirred. This was followed by addition of 6 g of sodium. A white precipitate was formed. This was benzoic salt. To the resulting mixture14.2g of ammonium chloride was added and stirred for 1 hour. The mixture was kept still so that ammonia escapes through evaporation. The residue was dissolved in 300ml of water. The mixture was poured into 200g of and acidified to pH of about 4 by adding 70ml of 10% hydrochloric acid. The mixture was extracted using ether in portions of 100ml and washed with 50ml of saturated aqueous solution of sodium chloride. This was followed by drying over using 2g of anhydrous magnesium sulphate. Then ether solution was separated from drying agent and concentrated at low pressure. The residual oil is distilled from 25ml claisen flask to obtain 1, 4-dihydrobenzoic acid. References Brown, W.H. et al. 2012. Organic chemistry. Belmont: Cengage Learning. Carruthers, W. and Coldham, I. 2004. Modern methods of organic chemistry synthesis. New York: Cambridge University Press. Gladysz, J., Curran, D. and Istavan, T. 2004. Handbook of flourous chemistry. Weinheim: Willey-VCH. Starky, L. 2012. Introduction to strategies for organic synthesis. Hoboken: John Willey & Sons. US Department of Health and Human Services. 2011. Report on carcinogens: Washington: Diane Publishing. Read More