Concept (explain why this is so..)

Problem # 744

After a sample of optically pure (S)-2-ethyl-cyclohexanone is dissolved in an aqueous solution for several hours, a significant loss of optical activity is observed. Explain.

Problem # 730

N,N-dimethylformamide (DMF) is shown below. Based on its structure, you might expect to see only one -CH3 signal in the 1H NMR spectrum. But instead DMF shows two different -CH3 signals. Explain.

Problem # 726

Show two esters that would yield the two alcohols below after treatment with lithium aluminum hydride.

Problem # 721

Rank each of the four compounds below in order of decreasing acidity (1 = most acidic).

Problem # 720

Base your answers to the three problems below on your knowledge of electron donating groups and electron withdrawing groups (EDG and EWG).


a) Based on the pKa's listed below, Is formic acid more or less acidic than acetic acid? Propose an explanation why.

b) If acetic acid were added to a pH = 4.7 buffer solution, what percentage of it would be in its acetate (conjugate base) form?

c) Methoxy (-OCH3) is usually considered an EDG. But based on the pKa of methoxy acetic acid, do you think this is always the case? Explain.

Problem # 717

Rank each of the eight compounds A through H below in order of decreasing acidity (1 = most acidic).


Don't get intimidated! What are the differences between these compounds?

Consider electron withdrawing groups (EWG), resonance, hybridization, and the functional group of the acidic proton.

Problem # 715

α-D-glucose is shown below.

a) Is α-D-glucose an acetal, hemiacetal, ketal, or hemiketal?

b) Draw the carbonyl form of α-D-glucose.

Problem # 713

When a carbonyl is treated with semicarbazide under acidic conditions an "imine" is produced called a semicarbazone.

Which of the two products below is the correct structure for a semicarbazone? Explain.

Problem # 710

Rank the carbonyls A-D below in order of decreasing electrophilicity (reactivity with nucleophiles).

(1 = Most reactive).  Explain your reasoning.

Problem # 703

Show two ways to prepare the ether below from a combination of an alcohol and an alkyl halide via the Williamson ether synthesis.

Is one way better than the other? Why?