Question

hi, please help me with number 7. thank you

EXPERIMENT SEVEN SODIUM BOROHYDRIDE REDUCTION OF ACETOPHENONE HOCH, DISCUSSION The reduction of an aldehyde or ketone with sodium borohydride is straight forward and usually affords a high yield of the alcohol. The usual procedure (and the one employed in this experiment) involves dissolving the borohydride in 95% ethanol and adding the carbonyl compound to this solution. To ensure complete reaction, an excess of sodium borohydride is used. The reaction between sodium borohydride and acetophenone is exothermic. Therefore, it is important to add the acetophenone drop-wise and to control the reaction temperature with an ice bath. After the reaction has been completed, the excess borohydride and the ethoxyborohydrides are destroyed with aqueous acid. Because hydrogen gas is evolved, this treatment with acid must be carried out in a fume hood or a very well ventilated room. Because ethanol, the reaction solvent, is water-soluble, a clean separation of organic and inorganic products cannot be achieved by a simple extraction with water and diethyl ether at this point. Too much product would be lost in the aqueous ethanol layer.) To circumvent this problem, the first step in the work-up is to boil off much of the ethanol. In a larger-scale reaction, the ethanol would be distilled and collected. In a small-scale reaction such as in this experiment, the ethanol can be boiled away in the fume hood. When most of the ethanol has been removed, the product 1-phenylethanol oils out. Water and diethyl ether are then added to the residue for the extraction of the organic compounds from the inorganic salts. The ether extract is dried with either sodium sulfate or magnesium sulfate. The crude product is obtained by distilling the ether. Because of its high boiling point, 1 phenylethanol cannot be distilled at atmospheric pressure. Although it could be vacuum-distilled, distillation could not separate it from unreacted starting matenal (if any) because the two compounds have boiling points only 1° apart. An infrared spectrum can be used to determine if any ketone is present in the product.

Answer 1

In IR we should see a band around 1700 cm-1 for carbonyl stretching.

In NMR, the CH3 group appears as singlet at 2.1 which is characteristic of COCH3 group.we can see very small peak at 2.1 showing little impurity of acetophenone.