Question

Are the following correct?

1. Predict the splitting patern you would observe for the proton at C1 of 2,3-dimethyl-2-phenylbutane --> First off, which one is the C1 carbon? I am assuming it is the carbon attached to the benezine ring - Hence making the answer a singlet?

2. Which of the following m/z values corresponds to the molecular ion for the following compound --> C6H14O (2-hexanol)? C=12x6=72, O=16 and H=1x14=14. Combined I'm getting 102. However, in mass spec. the molecular ion is simply missing one electron. Would the answer be 102?

3. The allyl cation has how many pi molecular orbitals? Is the answer 4.

4. The LUMO of 1,3-pentadiene has how many electrons? Is the answer 2.

5. Unsaturated product results from reaction of cyclohexene with which of these?

a. Br2/CCl4 at 25 degrees Celsius --> Incorrect - Gives a saturated product

b. NBS/CCl4, ROOR --> Yes

c. HCl, ROOR --> No

d. HCl, no peroxides --> No

e. More than one of these

Answer 1

1. In the compound 2,3-dimethy-2-phenylbutane,

CH3-C(CH3)(Ph)-CH(CH3)-CH3

C-1 (CH3 at the beginning) carbon will appear as a singlet

2. The molecular ion for C6H14O = 102 (m/z)

Mass spec showing m/z 101 could be due to loss of a H from the OH from the molecule. An RO radical is a stable species

3. The number of pi-electrons in an allyl cation : 2

4. The number of electrons in LUMO of 1,3-pentadiene : 4

5. Unsaturated product results from reaction of cyclohexene with the reagent,

a. Incorrect (a vicinal dibromo alkane is the product here)

b. Correct [Allylic substitution with a Br radical gives allyl bromide prodduct]

c. Incorrect [hydrochlorination via anti-Markovnikov's rule of addition yields alkyl halide]

d. Incorrect [Hydrochlorination via Markovnikov's rule of addition]