UTC: Sunday, October 22nd, 2017

Intro to Organic Chemistry Notes Task Answers

Here you’ll find the answers to the Tasks that are embedded in the current Introduction to Organic Chemistry Notes.


UNIT 01 – Nomenclature


Task 1a

Alkanes

1.

(i) 2,2-dimethylbutane

(ii) 2,3,5-trimethyl-4-propylheptane

(iii) 3,3-diethylhexane

(iv) 2,4-dimethylpentane

(v) 4-ethyl-2,2,5-trimethylheptane

2.

(i)

2methylpropane

 

 

(ii)

3methylheptane

 

(iii)

23dimethylbutane

 

(iv)

226trimethyloctane

 

(v)

13diethylcyclobutane

Alkenes & Alkynes

3.

(i) But-1-ene

(ii) But-2-yne

(iii) 4-methylhex-2-yne

(iv) 4-methylpent-2-yne

(v) Buta-1,3-diene

4.

(i)

Photo Sep 24, 7 18 59 AM

(ii)

Photo Sep 24, 7 19 49 AM

(iii)

Photo Sep 24, 7 20 53 AM

(iv)

Photo Sep 24, 7 21 29 AM

(v)

Photo Sep 24, 7 46 49 AM

Halogen Compounds

5.

(i) 1-iodopentane

(ii) 3-methyl-4-ethylnonanoyl bromide

(iii) Bromobenzene

(iv) (chloromethyl)benzene (benzyl chloride)

(v) 2-bromopropane

6.

(i)

Photo Sep 24, 10 20 09 AM

(ii)

Photo Sep 24, 10 21 08 AM

(iii)

Photo Sep 24, 10 21 38 AM

(iv)

Photo Sep 24, 10 33 09 AM

(v)

Photo Sep 24, 11 02 53 AM

Alcohols

7.

(i) Pentan-3-ol

(ii) 2-methylbutan-2-ol

(iii) 3-bromobutan-2-ol

(iv) 3-phenylbutan-1-ol

(v) 3-nitrophenol

8.

(i)

Photo Sep 24, 11 17 19 AM

(ii)

Photo Sep 24, 11 17 46 AM

(iii)

Photo Sep 24, 11 18 24 AM

(iv)

Photo Sep 24, 11 19 17 AM

(v)

Photo Sep 24, 11 19 48 AM

Aldehydes & Ketones

9.

(i) Butanal

(ii) 3-methylbutan-2-one

(iii) 2-methylpropanal

(iv) 3-methylbutan-2-one

(v) 3-phenylpropanal

10.

(i)

Photo Sep 24, 11 28 25 AM

(ii)

Photo Sep 24, 11 29 01 AM

(iii)

Photo Sep 24, 11 29 28 AM

(iv)

Photo Sep 24, 11 30 01 AM

(v)

Photo Sep 24, 11 30 25 AM

Carboxylic Acids & Derivatives

11.

(i) Propanoic acid

(ii) 3-hydroxypentanoic acid

(iii) 2,2-dimethylpropanoic acid

(iv) 2-methylpropanoyl chloride

(v) 2-phenylpropanoic acid

12.

(i)

Photo Sep 24, 11 39 50 AM

(ii)

Photo Sep 24, 11 40 21 AM

(iii)

Photo Sep 24, 11 41 01 AM

(iv)

Photo Sep 24, 11 41 27 AM

(v)

Photo Sep 24, 11 41 55 AM

Aromatics

13.

(i) (chloromethyl)benzene

(ii) 1,2-diethylbenzene

(iii) 4-bromophenol

(iv) 2-chlorotoluene

(v) 2-nitrobenzoic acid

14.

(i)

Photo Sep 24, 12 05 04 PM

(ii)

Photo Sep 24, 12 05 36 PM

(iii)

Photo Sep 24, 12 06 05 PM

(iv)

Photo Sep 24, 12 06 31 PM

(v)

Photo Sep 24, 12 07 01 PM

Nitrogen Compounds

15.

(i) propanonitrile

(ii) N-methylaniline

(iii) 2-aminobenozic acid

(iv) N,N-diethylethanamine

(v) 3-phenylbutanonitrile

16.

(i)

Photo Sep 24, 12 07 31 PM

(ii)

Photo Sep 24, 12 07 50 PM

(iii)

Photo Sep 24, 12 08 24 PM

(iv)

Photo Sep 24, 12 09 12 PM

(v)

Photo Sep 24, 12 09 58 PM

 

 

 


UNIT 02 – Isomerism


Task 2a

1.

Photo Jul 12, 9 13 14 AM

Photo Jul 12, 9 13 49 AM

Photo Jul 12, 9 14 14 AM

2.

Hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane.

Photo Jul 12, 9 21 31 AM

Photo Jul 12, 9 21 04 AM

Photo Jul 12, 9 20 47 AM

Photo Jul 12, 9 19 53 AM

Photo Jul 12, 9 20 15 AM

3.

Nonanes

2-methylnonane

3-methylnonane

4-methylnonane

5-methylnonane

Pentanes

2,4-dimethyl-3-(1-methylethyl)pentane

3,3-diethyl-2-methylpentane

3-ethyl-2,2,3-trimethylpentane

3-ethyl-2,2,4-trimethylpentane

3-ethyl-2,3,4-trimethylpentane

2,2,3,3,4-pentamethylpentane

2,2,3,4,4-pentamethylpentane

Task 2b

1.

Photo Jul 12, 11 25 14 AM

Photo Jul 12, 11 25 40 AM

2. IUPAC nomenclature insists that locants be kept as low as possible. As a result, butan-3-ol and butan-4-ol could (and should) be called butan-2-ol and butan-1-ol respectively, when counting from the other end of the chain.

3.

3 isomers; 2-mehylphenol, 3-methylphenol and 4-methylphenol.

Photo Jul 12, 11 34 40 AM

Photo Jul 12, 11 34 56 AM

Photo Jul 12, 11 35 23 AM

4.

1,1-dibromobutane
1,2-dibromobutane
1,3-dibromobutane
1,4-dibromobutane
2,2-dibromobutane
2,3-dibromobutane
1,1-dibromo-2-methylpropane
1,2-dibromo-2-methylpropane
1,3-dibromo-2-methylpropane

Task 2c

1.

Photo Jul 12, 1 08 43 PM

Photo Jul 12, 1 09 13 PM

2.

Many answers possible here, but perhaps the simplest are pent-1-ene and cyclopentane;

Photo Jul 12, 1 12 25 PM

Photo Jul 12, 1 12 02 PM

3.

Many answers possible here, but perhaps the simplest are hexanal and hexan-2-one;

Photo Jul 12, 1 15 05 PM

Photo Jul 12, 1 15 49 PM

Task 2d

The cis isomer. Since a water molecule is eliminated by combining the -OH groups of two acid groups, they must be on the same side of the molecule to facilitate the dehydration reaction.

Task 2e

1.

E

task2e1E

Z

Task2e1Z

2.

There are no identical groups attached to each of the C atoms of the double bond, that can be grouped as being on the same side (cis) or different sides (trans).

3.

E

Task2e3E

Z

Task2e3Z

Task 2f

1.(a)

Task2f1a

(b)

Task2f1b

Task 2g

1.

Least stable: Eclipsed with CH3 groups aligned (#4), then

Eclipsed with CH3 and H aligned (#2), then

Staggered with CH3 groups adjacent to one another (gauche) (#1), then

Most stable: Staggered with CH3 groups opposite one another (anti) (#3)

2.

Task2g2

Task 2h

1.

(a) 1,1-dichloropropane, 1,2-dichloropropane, 1,3-dichloropropane, 2,2-dichloropropane

(b) but-1-ene, but-2-ene, 2-methylpropene, cyclobutane, methylcyclopropane

(c) 1-bromobutane, 2-bromobutane, 2-bromo-2-methylpropane, 1-bromo-2-methylpropane

(d) 1-methyl-2,3-dinitro benzene, 1-methyl-2,4-dinitro benzene, 1-methyl-2,5-dinitro benzene, 1-methyl-2,6-dinitro benzene, 1-methyl-3,4-dinitro benzene, 1-methyl-3,5-dinitro benzene

2.

(a) Ethanoic acid, methyl methanoate, hydroxyethanal

(b) cis-Ethene-1,2-diol, trans-Ethene-1,2-diol, Ethene-1,1-diol

(c) Those in (a) are functional group isomers of those in (b)

3.

(a) cis-1,2-dibromoethene, trans-1,2-dibromoethene, 1,1-dibromoethene

(b) chloroethene (no isomers)

4.

Task2h4ad

(e) They each have a chiral center.

5.

R


UNIT 03 – Mechanisms


No Tasks as yet


UNIT 04 – Reactions


Task 4a

1.

Propan-1-ol and propan-2-ol. (1° and 2° alcohols)

2.

CH3CH2CH2OH + [O] → CH3CH2CHO (propanal) + H2O

CH3CH2CHO + [O] → CH3CH2COOH (propanoic acid)

Color change from orange to green.

CH3CH(OH)CH3 + [O] → CH3COCH3 (propanone) + H2O

Color change from orange to green.

3.

Cr2O72- + 14H+ + 6e → 2Cr3+ + 7H2O

MnO4 + 8H+ + 5e → Mn2+ + 4H2O


UNIT 05 – Structure Determination


Task 5a

C5H6O3

Task 5b

1.

Photo Jul 12, 3 39 41 PM

Photo Jul 12, 1 08 43 PM

Photo Jul 12, 3 40 04 PM

Photo Jul 12, 3 40 26 PM

Photo Jul 12, 3 40 53 PM

Ethanol and propan-2-ol give positive iodoform tests.

2.

Only the pair in (c).

Task 5c

P = Propan-1-ol. Peak at 3300 cm-1 due to O-H group. No carbonyl peak. Peaks around 3000 cm-1 are C-H peaks.

Q = Propanal. Peak at 1750 cm-1 due to the carbonyl group, C=O. No O-H peak. Peaks around 3000 cm-1 are C-H peaks.

R = Propanoic acid

IR Propanoic acid

Source: SDBSWeb

Task 5d

1.

91 = [C6H5CH2]+

92 = [C6H5CH3]+

93 = [13C6H5CH3]+

2.

29 =[CH3CH2]+

43 = [C=OCH3]+

72 = [CH3CH2C=OCH3]+


UNIT 06 – Synthesis


Task 6a

1.

90.5%

2.

80.1%