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5 Questions in Examination 2 on Elementary Organic Chemistry II | CH 232, Exams of Organic Chemistry

Material Type: Exam; Professor: Blackstock; Class: Elem Organic Chem II; Subject: CH-Chemistry; University: University of Alabama; Term: Unknown 1989;

Typology: Exams

Pre 2010

Uploaded on 08/19/2009

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Exam #2 Chemistry 232 Blackstock July 26, 2007
Name:____________________________(print) Honor Pledge: ______________________________ (sign)
You have 90 minutes to complete this exam. Exams are due at 9:30 AM. Partial credit will be given for
partially correct answers in most cases, so be sure to show your work.
I. General Knowledge & Exam 1 review ( pts)
1. (34 pts) Give the structures of the molecules written below and provide the names of any structures shown.
allyl alcohol
Grignard reagent derived from
benzyl bromide
ethanol acetal of cyclopentanone
Gilman reagent derived
from bromobenzene
THF
Wittig reagent used to prepare
styrene
product of mCPBA oxidation
of trans-2-pentene
Claisen rearrangement product of
allyl vinyl ether
disulfide derived from
ethane thiol
DMSO
a monosubstituted benzene
which will undergo meta EAS
hydrate of benzaldehyde
hydrazone of
cyclobutanone
O
O
H2N NH2
OO
P
Ph
Ph
Ph
_____________________
_____________________
_____________________
pf3
pf4
pf5

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Exam #2 Chemistry 232 Blackstock July 26, 2007 Name:____________________________(print) Honor Pledge: ______________________________ (sign) You have 90 minutes to complete this exam. Exams are due at 9:30 AM. Partial credit will be given for partially correct answers in most cases, so be sure to show your work. I. General Knowledge & Exam 1 review ( pts)

  1. (34 pts) Give the structures of the molecules written below and provide the names of any structures shown. allyl alcohol Grignard reagent derived from benzyl bromide ethanol acetal of cyclopentanone Gilman reagent derived from bromobenzene THF Wittig reagent used to prepare styrene product of mCPBA oxidation of trans- 2 - pentene Claisen rearrangement product of allyl vinyl ether disulfide derived from ethane thiol DMSO a monosubstituted benzene which will undergo meta EAS hydrate of benzaldehyde hydrazone of cyclobutanone O O H 2 N NH 2 O O Ph P Ph Ph

I. general knowledge (p1) ______ (34 pts) (p2) ______ (18 pts) II. reactions ______ (29 pts) III. mechanisms ______ (12 pts) IV. synthesis ______ (12 pts) TOTAL ______ (105 pts) (5 pts extra credit)

  1. (14 pts) (a) (6 pts) One of the most common reactions of aldehydes and ketones is nucleophilic addition to the carbonyl group. An example is acetal formation. Under acidic conditions, write the missing intermediates below for the formation of a hemi-acetal intermediate. Show e-pushing arrows for any step involving nucleophilic attach at the carbonyl. HO OH O H
  • (^) (cat) O OH HO hemiacetal (b) (8 pts) Write the intermediates for the next 4 steps to convert the hemiacetal to the product acetal. Show e- pushing arrows for each step except H+^ transfer steps. O OH HO hemiacetal acetal O O
  1. (4 pts) Give two possible ways of using Grignard chemistry to construct the following alcohol. Show complete reactant structures in each case. OH

IV. Mechanism (12 pts) Provide detailed mechanisms for the transformations given below, showing every step in the process clearly and using electron pushing arrows for all steps except protonations/deprotonations. (a) (6 pts) NH 2 OH, H+^ catalysis N OH

  • H 2 O O (b) (6 pts) O O
  • 2 H 3 C MgBr
  1. rxn in ether
  2. H 3 O+^ H^3 C OH H 3 C OH

V. Synthesis (10 pts) Provide a reaction sequence to accomplish the following conversions (left to right) using any reagents needed to convert the carbons of the starting material into the product structure. Show reactants, products, and necessary reagents for each step in the sequence, but do not show mechanisms here. (1) (6 pts) convert O to O (2) (6 pts) O convert to OH OH