8A Exam 2B F’18 Last Name, First Initial ________________________

1 ______

1. Fundamentals & Nomenclature (a) (5 points) The following compounds are listed in order of acidity (most acidic on the left). Indicate the approximate pKa value that belongs to each compound in the boxes provided.

H2O H3O+

O

NH3 +NH4

(a) (5 points) Provide the degrees of unsaturation in the following structures or formulas.

(c) (10 points) Draw structures corresponding to the following names. 3E,5Z-2,6-dimethyl-1,3,5,7-octatetraene 3-butyl-2-heptene (d) (10 points) Identify the functional groups in the following molecules. Draw a dipole arrow for each polar bond.

not

35 10 19 16 O

Goths GHzoGHS Golfo C9Hl8

2 3 2 6 I

TTT TT TTT TT

ahh ryu

athene ffamide afaldehyde

Fargue

8A Exam 2B F’18 Last Name, First Initial ________________________

2 ______

2. Reaction Warm-up (a) (10 points) Add curved arrows to show the mechanism in the following reactions. (i)

(ii)

(b) (15 points) Predict the products of the following polar reaction, a step in the citric acid cycle for food metabolism, by interpreting the flow of electrons indicated by the curved arrows:

(c) (5 points) The following carbocations rearrange to the more stable ions shown. Add curved arrows to explain these rearrangements.

(d) (5 points) Reaction of HBr with 2-methylpropene yields 2-bromo-2-methylpropane. What is the structure of the carbocation formed during the reaction? Curved arrows are welcomed but not necessary here.

22d z

I eb r2 I

100OH

002C4708 HDcop

a rH2 3

to5pts

8A Exam 2B F’18 Last Name, First Initial ________________________

3 ______

3. Alkene Reactions (45 points) FILL IN THE BOX with the missing reactants and products for any four reactions. It is not necessary to indicate stereochemistry on this page. Draw a large ‘X’ over the two reaction boxes to skip, otherwise (a)-(d) will be graded – we will not choose the best ones for you! (a)

(b)

(c)

(d)

(e)

HI I

(f)

I lptseachtI

Ey

I 0322miHt

fagot too orotherageacidok

TF

TTOH

s

8A Exam 2B F’18 Last Name, First Initial ________________________

4 ______

4. Stereoselective Reactions & Alkyne Reactions (50 points) FILL IN THE BOX with the missing reactant and product for any five reactions. Draw a large ‘X’ over the two reaction boxes to skip, otherwise (a)-(e) will be graded. (a)

(b)

(c)

(d)

(e)

(f)

(g)

1. NaNH2, NH3

2. CH3CH2Br

9pts each

450

rate as EE'd7pts

51.0504PYg 5g 2NaH or OsouNM0

or IN

Ra o

k mgoss O

E H II l 7pts

era Ee3pts

EIFEr

8A Exam 2B F’18 Last Name, First Initial ________________________

5 ______

5. Reaction Mechanisms & Organic Synthesis (a) (25 points) Reaction of 2-methylpropene with CH3OH in the presence of H2SO4 catalyst yields methyl tert-butyl ether by a mechanism analogous to that of acid-catalyzed alkene hydration. Write the mechanism, using curved arrows and drawing the intermediate in each step.

(b) (20 points) There are several steps required to synthesize butanal from 1-pentyne. Outline this synthesis using any reagents needed to complete this transformation. Draw the product after each synthetic step. No mechanisms, intermediates, or arrow-pushing necessary.

Hoof4

I y B

h t EiE t

5 intend 4pts

intmI

HasaTECH

s.Enittolion4nx

HzLindlar

HzPdC 0pts