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Name: __________________ Date: 04/16/2013

PID #: __________________

Section #: _______________

TA name: _______________

QUIZ III

CEM 251 – Spring 2013 (Instructors: Prof. Robert Maleczka and Hovig Kouyoumdjian)

Total possible points = 50+5

Question 1 23pts _______

Question 2 12pts _______

Question 3 15pts _______

Bonus 5pts _______

_______________________

Total Points

 

 

 

 

Spectra obtained from: SDBSWeb: http://sdbs.riodb.aist.go.jp  

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Question 1: (23 points)

Propose a structure for this compound: C7H7XO (X can be Br or Cl)

 

Mass Spectrograph

IR Spectrum

1H-NMR Spectrum

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1- Determine the nature of the halogen atom that you have in this compound. Explain why?

2- Now that you have a complete molecular formula, calculate the degree of unsaturation in this compound. Show your work.

DU=

3- How many carbon peaks you have in the 13C NMR spectrum. Explain why you have fewer carbon peaks in the spectrum knowing that the molecular formula has 7 carbons?

X is: Explain briefly:

 

13C-NMR Spectrum

How many carbon peaks?

Explain why you have fewer carbon peaks, knowing that the molecular formula has 7 carbons?

 

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4- a) What is the multiplicity of the peak at 3.8 ppm (1H-NMR spectrum)?

b) What is the integration of the peak at 3.8 ppm?

c) Explain why this peak occurs at 3.8 ppm.

d) Based on your answers propose a fragment from the compound.

5- Explain how you would characterize the peaks between 6.5 and 7.5 ppm (1H-NMR spectrum). Propose a fragment of the compound.

6- Using the information in all 4 spectra above, propose a structure for the unknown compound.

Draw the complete structure here:

 

a)

b)

c)

d) Propose a fragment:

 

Propose a fragment: Explain briefly:

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Question 2: (12 points)

Draw the major products or starting materials for the following reactions (Show stereochemistry if applicable).

 

 

 

 

 

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Question 3: (15 points)

Consider the reaction below to answer the following question(s):

 

1- The nucleophile in this reaction is ____.

2- The electrophile in this reaction is ____.

3- The kinetically controlled product in this reaction is _____.

4- The product that results from 1,4-addition is _____.

5- Write a stepwise mechanism that accounts for both of the products shown. Show all intermediate structures and electron flow with arrows. Circle the most stable product.

Show your work here:

Intermediate:

Intermediate:

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Bonus 4: (5 points)

The IR spectrum below is for caffeine: Which one is caffeine? Circle the molecule and explain briefly why you chose that answer below.

Explain briefly:

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