CHEM 2OB3 Midterm Test Feb 27, 2010 VERSION 1

CHEM 2OB3

Midterm Test Feb 27, 2010

VERSION 1

NAME (First & Last): ___ _____________

ID#: _______________

Lab Station: ______

(1-60, Print ‘E’ if you are exempt from the labs)

Please circle your lab section in the table below.

Group Monday Tuesday Wednesday Thursday Friday

I L01 L02 L03 L04 L05

II L06 L07 L08 L09 L10

Duration: 120 minutes Instructor: Dr. Capretta

Instructions:

This examination paper consists of 15 pages, containing 20 (twenty) multiple choice (MC) questions, and 5 short-answer questions. You are responsible for ensuring your copy of the question paper is complete and no pages are missing.

Answer all the MC questions on optical scan sheets. Follow the instructions on the optical scan sheets, and the University rules for OMR exams which are reproduced on page 2. Failure to follow instructions may result in loss of credit. NOTE: if the midterm is answered in pencil, it will not be able to be remarked. Model Kits are permitted, calculators are not permitted. You are responsible for ensuring all answers are in the correct place, and that you follow the correct procedure for filling out the scan sheet.

Mark your student number in the space provided on the sheet on Side 1 AND FILL IN THE CORRESPONDING BUBBLES UNDERNEATH. Now enter your version number, which can be found on the top right hand corner of this page, by filling in the BUBBLE in the “version” column provided. You MUST sign the sheet in the space provided.

All McMaster rules and procedures relating to Academic Dishonesty and Academic Integrity apply to this exam; all violations will result in a penalty. Students must do their own work. A program designed to detect similar answers will be used for this exam.

You MUST also complete ALL the information at the top of this page.

MC

Written Section

Q21

Q22

Q23

Q24

Q25

Total

(written)

OMR EXAMINATION – STUDENT INSTRUCTIONS

NOTE: IT IS YOUR RESPONSIBILITY TO ENSURE THAT THE ANSWER SHEET IS PROPERLY COMPLETED. YOUR EXAMINATION RESULT DEPENDS UPON

PROPER ATTENTION TO THESE INSTRUCTIONS.

The scanner, which reads the sheets, senses the bubble shaded areas by their non-reflection of light. A heavy mark must be made, completely filling the circular bubble, with an HB pencil. Marks made with a pen will NOT be sensed. Erasures must be thorough or the scanner will still sense a mark. Do NOT use correction fluid on the sheets. Do NOT put any

unnecessary marks or writing on the sheet.

1. On SIDE 1 (red side) of the form, in the top box, print your student number, name, course name, and the date in the spaces provided, in pen. Then you MUST write your signature, in the space marked SIGNATURE.

2. In the second box, mark your student number and test or exam version number (1, 2, 3 …) by filling in the corresponding bubbles underneath, in pencil.

Section 1 – Multiple Choice [Questions 1 through 20 are 2 marks

each].

Use the Scheme below for Questions 1 though 4. Testosterone is one of the most important male steroid hormones. Shown below are a number of transformations using testosterone as the starting material. O H OH H H H O H H H O HO H OH H H H O H OH H H H HO H OH H H H testosterone A B _C D

Question 1: The reagents suitable to convert testosterone to compound A are: (a) Ni, H2, high pressure

(b) PCC

(c) 1. LiAlH4; 2. H3O+ (d) Pd-C, H2

(e) none of the above

Question 2: The reagents suitable to convert testosterone to compound B are: (a) Ni, H2, high pressure

(b) PCC

(c) 1. LiAlH4; 2. H3O+ (d) Pd-C, H2

Question 3: The reagents suitable to convert testosterone to compound C are: (a) Ni, H2, high pressure

(b) PCC

(c) 1. LiAlH4; 2. H3O+ (d) Pd-C, H2

(e) none of the above

Question 4: The reagents suitable to convert testosterone to compound D are: (a) Ni, H2, high pressure

(b) PCC

(c) 1. LiAlH4; 2. H3O +

(d) Pd-C, H2

(e) none of the above

Question 5: The structure of ascorbic acid (vitamin C) appears below. Which of the following statements is true.

HO

O H

H HO

CH₂OH OH

O

ascorbic acid

(a) Ascorbic acid has an L-configuration (b) Ascorbic acid has a D-configuration.

(c) Ascorbic acid has neither the D- or the L-configuration. (d) Ascorbic acid has both the D- and the L-configuration. (e) Ascorbic acid is achiral.

Question 6. The aldol reaction of cyclohexanone produces which of these self condesation products?

O O O O

O O

Question 7. For the ketone given, which structure represents its kinetic enolate:

O

O O- O

-(a) (b) (c)

O

-(d) (e)

O

-Question 8: Which of the following is a Haworth α-D-allose (the 3-epimer of α-D-glucose)?

O CH₂OH OH

OH

OH

OH O

CH₂OH OH

OH

OH OH

O CH₂OH OH

OH OH

OH

O CH₂OH

OH

OH OH

OH O

CH₂OH

OH OH

HO OH

(A) _{(B) (C)}

(E) (D)

Question 9. Amylose (a constituent of starch) adopts a “barrel” shape while cellulose chains (found in plants) are relatively straight. This is a result of the fact that:

(a) Amylose is composed of D-glucose while cellulose is composed of L-glucose (b) Amylose is composed of D-glucose while cellulose is polymer of D-galactose

(c) Linkages between the D-glucose units is mainly α(1->4) in amylose and mainly β(1->4) in cellulose

(d) Linkages between the D-galactose units is mainly β(1->4) in amylose and mainly α (1->4)in cellulose

Question 10. Given the Fisher project of D-glucose below, Compound X represents: CHO OH H H HO OH H OH H

CH₂OH

CHO H HO OH H H HO H HO

CH₂OH

D-glucose Compound X

(a) Another diasteromer of D-glucose (b) The anomer of D-glucose

(c) L-glucose (d) D-fructose

(e) L-allose (the 3-epimer of L-glucose)?

Question 11. What is the missing reagent?

?

OH-, H₂O heat

O

(a) CH₃CCH₂CH₂CCH₃

(b) CH₃CCH₂CH₂CH₂CH O O

O O

(c) HCCH₂CH₂CH₂CH₂CH O O

(d) CH₃CCH₂CH₂CH₂COEt

O O

(e) O=CCH₂CH₂CH₂CH₂COEt

H O

Question 12. Which of the following compounds has the lowest pKa?

CH₃-NO₂ CH₃-CN

O

H

CH_3-CH₃

(a) (b) (c) (d) (e)

H O

Question 13: What is the best set of reagents to carry out the following transformation:

OCH3

CO₂Me

OCH₃ CHO

(a) 1. LiAlH(OtBu)3, Et2O, -78C; 2. H2O (b) PCC

(c) 1. LiAlH4; 2. H3O +

(d) 1. DIBAL-H; 2. H2O (e) none of the above

Question 14: Which of the following chemists was NOT born in Germany:

(a) G. Wittig (b) F.A.V. Grignard (c) R.L. Claisen (d) J.G. Schmidt (e) H.E.Fischer

Question 15. Which of these species is aromatic?

N

H

O

N

H

O

O

O

_S

..

..

..

..

..

..

..

..

..

..

..

(a)

(b)

(c)

(d)

(e)

Question 16. Which of the following carbonyl containing compounds exists primarily as its enol tautomer in solution?

O

(a) (b) (c) (d)

(e) None of the above. The keto form always predominates. H

O O

Question 17. What is the product from the following reaction?

O

O

1. NaOCH2CH3

EtOH

2.

3. H3O+

O ? O O O O O O O O O O

(a) (b) (c) (d) (e)

Question 18. Which of the following would undergo racemization in base?

C₆H₅CC₆H₅ O

I

C₆H₅ O H₃C

CH2CH3

II

C₆H₅ O H

CH₃

CH2C6H5

O H₃C

CH₃ H₃C

III IV

(a) I (b) II (c) III (d) IV

(e) Both III and IV

Question 19. Which of the following species would you expect to be antiaromatic?

(a)

(b)

(c)

(d)

(e)

Question 20. Which compound would you NOT expect to be aromatic?

(a)

(b)

(c)

(d)

(e)

O

S

H

_N

H

_B

N

Section 2 – Short Answer

Question 21 [20 marks] Draw the MAJOR product for ten of the twelve reactions below. If more than 10 are attempted, the first 10 will be marked.

OH

NH +

CrO₃Cl

-CH₂Cl₂

O

1. (CH₃CH₂)₂CuLi 2. H₂O

CHO

O

O

NaBH4

H2O

1. O₃

2. Zn, H₃O+

MgBr

+ O

1. ether

2. H3O+

C

C

C

O

H

C

CH

H

C

H

H

H

1. Br

, OH

, H

O

OH CN

HCl H₂O, heat

CHO

+ H2N H2O

H 1. NaNH2

2.

3. H₃O+ O

OH

H₂CrO₄

acetone, 35oC

CN

1. CH₃Li 2. H₃O+

H O

-Question 22: [8 marks] Draw the following carbohydrates in their open chain forms.

O OH

OH

OH HO

HOH2C

O HOH2C

HO

HO

OH OH

Question 23 [3 marks]: Draw D-ribulose in its five-membered cyclic hemiacetal Haworth form in the β-configuration. Note that in the β-configuration, hydroxyl group at the anomeric position is anti _{to the other ring hydroxyls.}

CH2OH

O

OH H

OH H

CH2OH

Question 24: [14 marks]: The following compounds were synthesized via the reaction of a carbonyl compound and another reagent. Provide the structures (in the boxes below) of the carbonyl and the reaction partner you’d mix together to get the product shown (don’t worry about conditions or the work up):

Carbonyl Containing Compound

Reaction Partner

OH

OH

N HN

O

O

OMe

O N

OH

SMe

N

H+

N H +

H₂O N H

+O_H H

H₂O

N H O

H N H

O H H + N H

H

+ O H

N H H

+

O H

H+

How can you insure that hydrolysis goes to completion?

Question 25. [15 marks]: The mechanism for the hydrolysis of an imine is illustrated below. Provide the appropriate “curly arrows” for each of the steps below in order to show the flow of electrons, draw all necessary lone pairs of electrons.