Discussion In this experiment benzoin (1) will be reduced to 1,2-diphenyl-1,2-ethanediol (2) by reaction with sodium borohydride NaBH4 (Equation 1). NaBH4 OH I OH OH H* 1 Equation 1 The "diol" product will then be reacted with acetone in the presence of an acid catalyst to form a ketal (3) (Equation 2). CH3 | CH3 OH I OH Acid H3C- CH3 3 Equation 2 22 -dimethet4,5-di phoned- 1,3-dioxolane Preparation of the Ketal In a 100 ml round-bottomed flask place 1.00 g (4.67 mmole) of the diol, 0.30 g (1.9 mmole) of anhydrous FeCl3 (Note! FeCl3 is a catalyst), and 30 ml of anhydrous acetone. Heat this solution at reflux for 20 minutes. Use boiling stones) A picture of a reflux set- up is available in the front of the lab manual. Have the lab instructor check your reflux set-up before you start. Cool the solution and add 10 ml of 10% aqueous K2CO3 and 50 ml of water. Extract the solution with two 20 ml portions of methylene chloride. (Is the methylene chloride layer the top or bottom?). The combined methylene chloride extracts should be washed with 25 ml of water and dried over Na2SO4. Remove the solvent by simple distillation. A picture of a distillation set-up is available in the front of the lab manual. Have the lab instructor check your distillation set-up before you start. The ketal will remain is the distillation flask. Add 15 ml of petroleum ether to the ketal and heat until it is boiling. If some solid remains decant the hot solution into an Erlenmeyer flask, The boil off the solvent until on 3 or 4 ml remain then place the flask into an ice bath. Crystallization can be induced by scratching. The product should be collected, washed with a little cold petroleum ether and its melting point recorded. This must be done immediately since the product is unstable) Make sure to get a product weight for your % yield calculation. Note! this is the last time I will be reminding you to get a weight of your product at the end of an experiment. You should do this for each experiment for the rest of the semester. Stop-2 this 0me react with Now the reactant CH CH3 OH HOCK+ Me Me final Product

Discussion In this experiment benzoin (1) will be reduced to 1,2-diphenyl-1,2-ethanediol (2) by reaction with sodium borohydride NaBH4 (Equation 1). NaBH4 OH I OH OH H* 1 Equation 1 The "diol" product will then be reacted with acetone in the presence of an acid catalyst to form a ketal (3) (Equation 2). CH3 | CH3 OH I OH Acid H3C- CH3 3 Equation 2 22 -dimethet4,5-di phoned- 1,3-dioxolane Preparation of the Ketal In a 100 ml round-bottomed flask place 1.00 g (4.67 mmole) of the diol, 0.30 g (1.9 mmole) of anhydrous FeCl3 (Note! FeCl3 is a catalyst), and 30 ml of anhydrous acetone. Heat this solution at reflux for 20 minutes. Use boiling stones) A picture of a reflux set- up is available in the front of the lab manual. Have the lab instructor check your reflux set-up before you start. Cool the solution and add 10 ml of 10% aqueous K2CO3 and 50 ml of water. Extract the solution with two 20 ml portions of methylene chloride. (Is the methylene chloride layer the top or bottom?). The combined methylene chloride extracts should be washed with 25 ml of water and dried over Na2SO4. Remove the solvent by simple distillation. A picture of a distillation set-up is available in the front of the lab manual. Have the lab instructor check your distillation set-up before you start. The ketal will remain is the distillation flask. Add 15 ml of petroleum ether to the ketal and heat until it is boiling. If some solid remains decant the hot solution into an Erlenmeyer flask, The boil off the solvent until on 3 or 4 ml remain then place the flask into an ice bath. Crystallization can be induced by scratching. The product should be collected, washed with a little cold petroleum ether and its melting point recorded. This must be done immediately since the product is unstable) Make sure to get a product weight for your % yield calculation. Note! this is the last time I will be reminding you to get a weight of your product at the end of an experiment. You should do this for each experiment for the rest of the semester. Stop-2 this 0me react with Now the reactant CH CH3 OH HOCK+ Me Me final Product

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter7: Alkynes

Section: Chapter Questions

Problem 7.18P: Show how to convert 1-butyne to each of these compounds. (a) CH3CH2CCNa+ (b) CH3CH2CCD

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