and water. YOU ay Tul 30 ethanol and water. Obtain the melting point and the IR,

Question

and water. YOU ay Tul 30 ethanol and water. Obtain the melting point and the IR,'H, and 13C NM the purified product for characterization. Compare these data with those tpec (v:v) ethanol % and meso-hydrobenzoin to determine the identity of the product and chemistry of the reduction. If authentic samples of racemic and meso the se are available, determine mixed melting points to support your assignmen (v or racenTic the stereo Dilute the combined aqueous methanol filtrates with water, neutralize the tion with sodium carbonate, and flush the mixture down the drain with exes sou 1. Determine the molar ratio of sodium borohydride to 9-fluorenone that in the experiment. Why is it necessary to use a greater molar ratio than theoretioin lete the reaction mixture is treated with water and acid to produce the desired sor 2. After the reaction between sodium borohydride and the ketone i s comp ondary alcohol. Explain this reaction by indicating the source of the h atom that ends up on the oxygen atom. ydroge 3. Sodium borohydride is fairly unreactive toward methanol, but adding a mines acid to this solution results in the rapid destruction of the sodium borohydri Explain. 4. How many molar equivalents of hydride does sodium borohydride contair 5. Using curved arrows to symbolize the flow of electrons, write the mechar for the steps involved in the conversion of 9-fluorenone to 9-fluorenol sodium borohydride followed by aqueous acid according to Equation 17.1 6. Suggest a structure for the white precipitate formed in the reaction of 9-fluon with sodium borohydride. whole ed. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in

Explanation / Answer

1)

molar mass of NaBH4 (sodium borohydride) = 37.8 g/mol

mole of NaBH4 = 0.05/37.8 = 0.0013 mole

molar mass of 9-fluoroenone =180.2 g/mole

mole of 9-fluoroenone = 0.61/180.2 = 0.0034

but 1 mole of NaBH4 can reduce 4 mole of 9-fluoroenone therefore

actual mole number of NaBH4 required for this reaction = 0.0034/4 = 0.00085

thus NaBH4 is used in excess.

NaBH4 is an active compound and reacts with any compound that can donate H+ and thus get easily deactivated. Thus NaBH4 can react with water, acids as well as base (to form salt). Even with passage of time some amount of NaBH4 will get deactivated as some moisture will enter the reagent bottle whenever it is opened for taking NaBH4.

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