Quiz 4 Answer Key

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1. Multiple Choice and fill-in-the-blank: Put best answer in the box provided.

Q1a

Which of the following statements is FALSE about Mass Spectrometry

a) MS can be used to determine the molecular formula of a compound

b) MS can be used to determine the amino acid sequence of a protein

c) MS can be used to determine the stereochemistry of a compound

d) MS can be used to determine if a compound contains a bromine

S1a

c) MS can be used to determine the stereochemistry of a compound

Q1b

Which of the following conditions is not used for reducing carbonyls or imines:

a) NaBH₃CN

b) NADH with alcohol dehydrogenase

c) Ag₂O, H₂O, NaOH

d) NaBH₄

e) H₂NNH₂, KOH, diethylene glycol

f) Ni catalyst with H₂

S1b

c) Ag₂O, H₂O, NaOH

Q1c

Which of the following synthesis conditions will not produce a carbonyl compound?

a) alkyne + BH₃, followed by H₂O₂ and NaOH

b) primary alcohol + PCC

c) alkene + O₃, followed by SMe₂

d) imine + water and acid catalyst

e) alkyne + Pd/C

S1c

e) alkyne + Pd/C

Q1d

In the formation of an acetal or an imine, a molecule of _H₂O__ is also produced.

Q2

The a-hydrogen of a carbonyl has a pK_a of ~20, compared to most alkanes that have a pK_a of ~50. This acidity is very important for synthetic transformations that we will soon be discussing. Draw the conjugate base that results when an aldehyde is treated with a generic base (such as NaOH), and explain why the aldehyde has increased acidity relative to other alkanes.

The anion can be stabilized through resonance.

(must show resonance structure for full credit!)

Q3

Predict the major product(s) for each of the following reactions.

Place your answer in the box provided.

Q4

An unidentified carbonyl compound with molecular formula C₅H₁₀O was mixed with an mystery alcohol and acid to make a new product. The carbonyl compound gives a negative Tollen’s test. The ¹H NMR spectrum of the product is provided below. With this information, provide the structure for each of the reaction components and put your answers in the boxes provided.