CHEM 140B

Final | Winter '15 | Whitesell
The absorption in the infrared at 1720 is indacative of the presence of :

A) Carbonyl group
B) Amine
C) Alcohol
D) Nitrile

The contribution of C-C bond is :

A) 146 Kcal/mole
B) 63 Kcal/mole
C) 99 Kcal/mole
D) 86 kcal /mole

The reduction of a simple C=C π bond is:

A) is exothermic by 63 kcal/mole
B) is endothermic by 63 Kcal/mole
C) is endothermic by 30 Kcal/mole
D) is exothermic by 30 kcal /mole

The difference in energy between 1-butene and trans-2-butene is:

A) 1.0 Kcal/mole
B) 1.7Kcal/mole
C) 2.7 Kcal/mole
D) 0.9 Kcal/mloe

The correct order of stability of carbocations is:

A) 1$^{\circ}$>2$^{\circ}$>3$^{\circ}$
B) 3$^{\circ}$>2$^{\circ}$>1$^{\circ}$
C) 2$^{\circ}$>3$^{\circ}$>1$^{\circ}$
D) 2$^{\circ}$>1$^{\circ}$>3$^{\circ}$

The methyl group of an ethyl group will appear in the proton NMR as a:

A) singlet
B) triplet
C) doublet
D) quartet

The maximum splitting of a methylene group an ethyl groupin a molecule with more than 3 carbon atoms is a:

A) quintet
B) triplet
C) sextet
D) quartet

At equilinrium, two compounds that differ in energy by 4.1 Kcal/mole will be in a ration of approximately:

A) 1;1
B) 10;1
C) 100;1
D) 1000;1

The contribution of a C-O bond is:

A) 146 Kcal/mole
B) 63 Kcal/mole
C) 99 Kcal/mole
D) 86 Kcal/mole

The correct average bond energies for the pi and sigma bonds between a carbon and oxygen in the following is:


A) 173 176 179
B) 179 176 173
C) 176 173 179
D) 173 179 176

In electrophilic, aromatic substitution, a bromine substituent on a benzene ring is:

A) Activating, o,p directing
B) Activating, m directing
C) Deactivating, o,p directing
D) Deactivating ,m directing

In electrophilic, aromatic substitution, a nitro group on a benzene ring is :

A) Activating, o,p directing
B) Activating, m directing
C) Deactivating, o,p directing
D) Deactivating ,m directing

In electrophilic, aromatic substitution, an alkyl group on benzene ring is:

A) Activating, o,p directing
B) Activating, m directing
C) Deactivating, o,p directing
D) Deactivating ,m directing

In electrophilic, aromatic substitution, an acyl group on a benzene ring is:

A) Activating, o,p directing
B) Activating, m directing
C) Deactivating, o,p directing
D) Deactivating ,m directing

2. Show the mechanism for the formation of the active electrophile for each of the following electrophilic aromatic substitution reactions. your mechanism must include curved arrows show the flow of electrons for all bonds made and broken, Answer outside the provided boxes will not receive credit.

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3. Shade the p orbitals in the diagrams below to depict the three molecular orbits of an allylic radical. Indicate the number of electrons in each orbital in the boxes provided. If an orbital i empty, write 0. Indicate the orbitals as bonding, antibonding, and non-bonding, as aprropriate.

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4. Provide a complete mechanism including curved arrows showing the flow of electrons for all bonds made and broken for the following reaction. You may use H+ as the source of a proton and you need not show where a proton goes when it is lost.

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5. Provide the expected major organic product from each of the following reactions. Do not show sterochemistry for products with only one center of chirality.If two centers are present in the product, you must show reative sterechemistry. You must place your answer in the box provided. Answer outside the boxes will not recive credit.

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6. Provide the expected major organic product from each of the following reactions. Do not show streochemistry for the products with one center of chirality. if two centers are present in the product, you must show relative stereochemisty. You must place your answer in the box provided. Answer outside the boxes will not recive credit.

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7. For each of the following reactions, provide two sets of reagents gthat could be used consecutively to convert the starting material to the product shown. Be very careful, the order of the two steps is important and simply reversing the two steps will result in a significant grade penalty. your answer must be placed within the provided boxes.

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8. Provide below is the proton NMR spectrum of an unkown. Propose a stucture consistent with spectrum. Your answer must be palce inside the box provided.

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9. Propose a sequence of reactions that could be used to prepare the alcohol shown below from any combination of reagents none of which has more than two carbon atoms. Your answer must fit completely inside the box provided.

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