Chemistry代写 Final Exam代写 Molecular models代写 oxygen代写

Dr John Carran Spring/Summer 2013

Chemistry代写 Multiple choice 30 questions, 30 marksPlease answer all multiple choice questions on a separate scantron sheet provided

Chemistry 281s Final Exam Duration 3 h

This exam has 2 sections Chemistry代写

Section 1

Multiple choice 30 questions, 30 marks

Please answer all multiple choice questions on a separate scantron sheet provided (do not use the virtual lab scantron sheet)

Answer all questions, no marks are deducted for wrong answers

Section 2 Chemistry代写

Short answer questions, 7 questions, 60 marks Please answer all short answer questions CLEARLY in the

answer booklet provided

Total 90 marks

Total pages 15 including this page and periodic table

READ ALL QUESTIONS CAREFULLY CHECK YOUR ANSWERS THOROUGHLY

Proctors are not able to answer questions on course content. You may use the back of this exam booklet as scrap paper

Molecular models are allowed in the exam contained in a clear ziplock bag.Chemistry代写

Section 1 Multiple Choice- Answer this section on the scantron sheet provided.

1. Select the most electronegative element from the listbelow:

A) H

B) O

C) N

D) B

E) C

2.Which structure(s) contain(s) an oxygen that bears a formal charge of+1?

A) I and II

B) III and IV

C) V

D) II

E) I and V

3. Which of the following species is/are not a resonance form(s) of the species in thebox?

A) I and II

B) II and III

C) III and IV

D) I and IV

E) II and IV

4. Which compound has the shortest carbon-carbonbond(s)?Chemistry代写

A) CH3CH3

B) CH2=CH2

C) HC≡CH

D) CH3CH2CH3

E) All carbon-carbon bonds are the same length.

5.What alkyl groups make up the followingether?

A) ethyl and phenyl

B) propyl and benzyl

C) ethyl and benzyl

D) propyl and phenyl

E) None of these

6. Which compound(s) contain(s) tertiary carbonatom(s)?

A) I, II, III

B) I

C) II, III

D) I, IV

E) V

7. Which compound listed below is a secondaryalcohol?Chemistry代写

A) CH3CHCH2CH3

OH

B) CH3CHCH2OH

CH3

C)

CH3COH

CH3

CH3

D) CH3CH2CH2CH2OH

E) CH3CH2CH2OCH3

8. Which compound would you expect to have the lowest boilingpoint?

9. What is/are the product(s) of the following acid-basemechanism?

10.Which of the following organic compounds is the strongestacid?Chemistry代写

A) C6H12 pKa = 52

B) CH3CH3 pKa = 50

C) CH3CH2OH pKa = 18

D) CH3CO2H pKa = 5

E) CF3CO2H pKa = 0

11. Select the strongest

A) OH−

B) RC≡C−

C) NH2−

D) CH2=CH−

E) CH3CH2

12. Which is the strongestacid?

A) CH2ClCH2CH2CH2CH2CO2H

B) CH3CHBrCH2CH2CH2CO2H

C) CH3CH2CH2CBr2CH2CO2H

D) CH3CH2CH2CHFCH2CO2H

E) CH3CH2CH2CF2CH2CO2H

13. The most stable conformation of butaneis:

A) I

B) II

C) III

D) IV

E) V

14. The preferred conformation of cis-3-tert-butyl-1-methylcyclohexane is the one inwhich:

A) the tert-butyl group is axial and the methyl group is equatorial.

B) the methyl group is axial and the tert-butyl group is equatorial.

C) both groups are axial.

D) both groups are equatorial.

E) the molecule exists in a boat conformation.

15. Select the structure forcis-3-methyl-6-vinylcyclohexene.

A) I

B) II

C) III

D) IV

E) V

16.Which alkene would yield 3-methylpentane when subjected to catalytic hydrogenation?Chemistry代写

 

17. How many moles of hydrogen (H₂) will react withcis-2,3,3-trimethylhepta-1,5-diene?

A) 0

B) 1

C) 2

D) 3

E) 4

18. Enantiomersare: Chemistry代写

A) molecules that have a mirror image.

B) molecules that have at least one stereogenic center.

C) non-superposable molecules.

D) non-superposable constitutional isomers.

E) non-superposable molecules that are mirror images of each other.

19. (R)-2-Chlorobutane is representedby:

A) I

B) II

C) III

D) IV

E) V

20. I and IIare:

A) constitutional isomers.

B) enantiomers.

C) identical.

D) diastereomers.

E) not isomeric.

21. Which molecule is a mesocompound?

A) I and II

B) IV and V

C) II and III

D) I, II and III

E) None of the above

22.Consider the S_N2 reaction of 2-iodopentane with CH₃CO₂-ion.

Assuming no other changes, what effect on the rate would result from simultaneously doubling the concentrations of both 2-iodopentane and CH₃CO₂– ion?

A) No effect.

B) It would double the rate.

C) It would triple the rate.

D) It would increase the rate four times.

E) It would increase the rate six times.

23. What product(s) would you expect to obtain from the following S_N2reaction?

A) I

B) II

C) An equimolar mixture of I and II.

D) III

E) None of these

24. Consider the substitution reaction that takes place when (R)-3-bromo-3-methylhexaneis treated with methanol. Which of the following would be true?

A) The reaction would take place only with inversion of configuration at the stereogenic enter.Chemistry代写

B) The reaction would take place only with retention of configuration at the stereogenic enter.

C) The reaction would take place with racemization.

D) No reaction would take place.

E) The alkyl halide does not possess a stereogenic center

26.Which nucleophilic substitution reaction is not likely tooccur?

A)I^–+  CH₃CH₂–Cl  ¾¾¾¾®  CH₃CH₂–I  + Cl^–

B)I^–+  CH₃CH₂–Br  ¾¾¾¾®  CH₃CH₂–I  + Br^–

C)I^–+ CH₃CH₂–OH ¾¾¾¾® CH₃CH₂–I + OH^–

D)CH₃O^–+ CH₃CH₂–Br ¾¾¾¾® CH₃CH₂–OCH₃ + Br^–

E) OH^–+ CH₃CH₂–Cl ¾¾¾¾® CH₃CH₂–OH + Cl^–

27. What would be the major product(s) of the followingreaction?

A) I

B) II

C) III

D) IV

E) More than one of the above

28.Which structure represents(R,Z)-5-methylhept-2-ene?

29. Your task is to convert 2-bromobutane to 1-butene in highest yield. Whichreagents would you use?Chemistry代写

A) KOH/H2O

B) KOH/CH3OH

C) CH3ONa/CH3OH

D) CH3CH2ONa/CH3CH2OH

E) (CH3)3COK/(CH3)3COH

30. Which of the following carbocations would NOT be likely to undergorearrangement?

Section II Short Answer questions. Answer all these questions in the answer booklet provided.Chemistry代写

31. Deduce the structure of an unknown compound A, C₈H₁₄, from the following data (4 marks).And briefly, but clearly explain your rationale (4 marks). A decolorizes Br₂/CCl₄, and upon reaction with excess H₂/Ni, affords 1-ethyl-2-methylcyclopentane. When A is subjected to ozonolysis, the following product isobtained.

32.Draw Fischer projection formula(e) of the major product(s) of the reaction betweenZ-3-methyl- 3-hexene and cold, alkaline KMnO₄ (6 marks).

33. Predict the major product(s) of the following reaction, giving regiochemical and/or stereochemical details as relevant (5 marks). Give the structure of the most important positively charged intermediate from the first step of this reaction mechanism (3marks).

34.Completelete the following reaction sequence, giving structural details AND NAMESof all key intermediates/product(s) (10 marks):

35. Give the MECHANISM (i.e. using curly arrows!) and products of the DielsAlder reaction between cyclopentadiene and maleic anhydride (shown below) (6 marks).

 

Which product is obtained in the greater yield and why? (4 marks).

36.Provide a reasonable synthetic strategy for the synthesis of trans-2- methoxycyclopentanol from bromocyclopentane (10marks)

37.Provide a mechanistic explanationfor the formation of the observed products in the following reaction. (8 marks)

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