2-3

Question 1

NMR chemical shift of the alkyl CH in benzoin is approx 6 ppm . this is significantly outside the normal 3-4 ppm range of a CH next to an alcohol. why is the chemical shift so high?

Answer 1

There are many nearby EWG functional groups such as the OH, C=O, and benzene. these add together to increase the chemical shift.

Question 2

would acid-base extraction be a useful approach to separate benzoin from benzil?

Answer 2

No
neither benzoin nor benzil are acidic or basic so won’t move to the water layer.

Question 3

How many H-NMR peaks should benzil have? it is fairly common for webmo to show 10 different NMR peaks for benzil. why does webmo show more peaks than there should be?

Answer 3

3 peaks
webmo looks at a static structure where peaks that are chemically equiv are not identical at the moment.

Question 4

in step 2, how were we able to use only 1 molecule of KOH for every 2 molecules of benzil and still get a reaction yield close to 100%?

Answer 4

both parts of the aldol condensation are catalyic in base so the hydroxide is regnerated

Question 5

main hazard of isopnetyl nitirte

Answer 5

low blood pressure/ toxic if ingested