Third Exam CHEM 256 – Organic Chemistry II

Prof. Bastin Spring 2013

Name ___________________________ Provide clear, concise answers using unambiquous, carefully drawn structures (where appropriate) for all of the questions. Good luck and enjoy!

1) _______/10 pts 2) _______/10 pts

3) _______/10 pts

4) _______/10 pts Total: ________/100 pts 5) _______/10 pts

6) _______/10 pts

7) _______/8 pts 8) _______/10 pts 9) _______/12 pts 10) _______/10 pts

Bastin – Exam #3 Chem 256 - Spring 2013

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1) (10 pts) Provide structures for the following compounds.

a) 1-Bromo-2-chloro-4-ethylbenzene

b) 3,5-dinitrotoluene c) 3-aminostyrene d) m-propylbenzaldehyde e) o-bromoaniline

Bastin – Exam #3 Chem 256 - Spring 2013

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2) (10 pts) Provide either common or IUPAC names for the following compounds?

a)

b)

c)

d)

e)

NO2

Cl

CH2Br

OCH3

Ph

OH

NH2

Cl

Cl

Cl

Cl

Cl

OH

Bastin – Exam #3 Chem 256 - Spring 2013

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3) (10 pts) Write a mechanism for the Friedel-Crafts alkylation of benzene using isopropyl bromide and AlBr3.

4) (10 pts) Predict whether the following molecules would be aromatic or non-aromatic.

Explain your reasoning.

B

H

Bastin – Exam #3 Chem 256 - Spring 2013

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5) (10 pts) Draw the product(s), if any, of the following reactions. Indicate stereochemistry where relevant.

a)

b)

c)

d)

e)

OH

OH

CrO3H2SO4

+ H3PO4

KMnO4

OH

NH2

Br2FeBr3

OH

CHO

Br2FeBr3

Bastin – Exam #3 Chem 256 - Spring 2013

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6) (10 pts) Provide the reagents needed to bring about the following transformations.

a)

b)

(c)

(d)

(e)

NH2

NH2

Cl

OH

OH

OH

OH

SO3H

Br H3N

O

Bastin – Exam #3 Chem 256 - Spring 2013

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7) (8 pts) Write resonance forms for the following ion.

8) (10 pts) How do you account for the fact that N-phenylacetamide is less reactive toward electrophilic aromatic substitution than aniline?

NH

C CH3

O

NH2

N-Phenylacetamide Aniline

Bastin – Exam #3 Chem 256 - Spring 2013

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9) (12 pts) Compound E (C8H10O2) is a neutral solid. Following are IR and 1H-NMR spectra of compound E. Deduce the structure of compound E and justify your structure by assigning all the appropriate peaks in the IR and NMR spectra and providing a short narrative describing what structural information each piece of data provided.

Bastin – Exam #3 Chem 256 - Spring 2013

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10) (10 pts) Provide a synthesis for the following molecule from benzene, inorganic reagents of your choice, organic reagents containing no more than four carbons, and pyridine.

OCH3

NO2

NO2

Bastin – Exam #3 Chem 256 - Spring 2013

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degrees of unsaturation = (#C atoms) – (#H atoms)/2 + (#N atoms)/2 + 1

Bastin – Exam #3 Chem 256 - Spring 2013

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Functional Group Frequency (cm-1) Intensity and Comments Alkanes

C–H C–C

2980-2850 1480-1420

medium to strong medium

Alkenes =C–H stretch =C–H bend C=C

3150-3000 980-960 (trans) 730-665 (cis) 1680-1600

medium; very weak for trans strong strong weak to medium

Alkynes ≡C–H C≡C

3350-3300 2260-2100

strong weak to medium

Alkyl halides C–Cl C–Br C–I

800-600 600-500 500

strong strong strong

Alcohols O–H C–O

3650-3300 1350-1050

strong and broad strong

Amines N–H C–N

3500-3100 ~1200

medium and strong; 1° amines-2 bands; 2° amines-1 band medium

Aromatics C–H stretch C–H bend C=C

3080-3020 900-730 1650-1580

weak to medium strong weak to medium

Carbonyls (C=O) Ketones/aldehydes Esters Amides Acids Acid Anhydride Acid Chlorides

1730-1700 1750-1735 1680-1630 1730-1700 1850-1740 1820-1770

strong strong; also has C–O stretch strong; 1° and 2° amides also have N-H stretch strong; also has O–H stretch strong; doublet strong

Nitrile (C≡N) 2200-2250 medium