Introduction to Organic Chemistry Tutorial

Raffles Junior College H2 Chemistry 2010/11 Lecture Notes 10 – Introduction to Organic Chemistry Lecturer: Mrs Kwie Shiao Yin

1. Draw the condensed structural formulae of the following compounds: (a) 4-bromo-1,2-dichlorobenzene (c) 3-methylpentanoic acid

(b) 2-methyl-1,3-butadiene (d) 1,4-dimethylcyclohexene

2. Give the displayed formulae of the following compounds: (a) 3-phenylbutan-2-ol

(b) 2-aminopentanedial

(c) 2-oxopropanoic acid

3. Give the IUPAC names of the following compounds: (a)

(b)

OH OH

O

CH3CHCHCH2CCH2CH 3

(c)

(d)

4. For each of the following compounds (i) predict the hybridisation and the geometry for each carbon atom (ii) mark any chiral carbons present with an asterisk. CH 3

(a)

(b)

Nootkatone (Grapefruit oil)

CH3

O Androstene-one

5. Give the structural formulae for all the compounds having the formula C5H10. State which types of isomerism are involved. Which of these isomers exist as a pair of stereoisomers? 6. State clearly which types of stereoisomerism are involved and mark any chiral carbons present with an asterisk. If they do display stereoisomerism, draw the corresponding stereoisomers. (a) hex-3-ene

(b) 2-bromobutane

(c) cyclobutane-1,2-dicarboxylic acid

(d) cyclohexene

(e) C6H5CH(OH)CH=CH2

(f) CH3CH=CHCH2CH(OH)CH3

7. Classify each of the following reactions as belonging to a particular category. (i.e. addition, substitution, elimination, rearrangement, hydrolysis, reduction, oxidation) (a)

+

CH3Br

(b) CH2=CH2

+

H2

(c)

+

HCN

AlBr3

Pt catalyst

HBr

+

CH3CH3

alc. KOH (d) CH3CH2CH2Cl

(e) CH3CH3

+

Cl2

+

(h) CH=CH2 HBr(g)

uv light

conc. H2SO4

(f) CH3CH2OH (g)

CH2=CHCH3 + HCl

heat

H2 O

H

CH3CH2Cl

+ HCl

CH2=CH2

+ H2 O

+

CHBrCH3

+ NH4+

CH(OH)CH3 KOH(aq) warm

Answers to Tutorial: 10 Chemistry

An Introduction to Organic

1. (a)

(c)

(b) CH2=C(CH3)CH=CH2

CH3CH2CH(CH3)CH2COOH

2. (a)

(d)

(b)

3. (a) 3-chloropent-1-ene (c) 4-ethyl-3,6-dimethyloctane 4. (a)

(c)

(b) 5,6-dihydroxyheptan-3-one (d) 2-ethyl-1,1-dimethylcyclobutane (b)

CH 3

* *

*

CH3

* O

Nootkatone (Grapefruit oil)

All carbons are sp3 hybridised except the 5 which are double-bonded. They are sp2 hybridised. sp3 hybridised – tetrahedral around C atom sp2 hybridised - trigonal planar around C atom

*

* *

*

*

Androstene-one

All carbons are sp3 hybridised except the 3 which are double-bonded. They are sp2 hybridised.

5. C5H10 10 structural isomers CH3CH2CH2CH=CH2

CH3CH2CH=CHCH3

geometric isomerism CH3CH2C(CH3)=CH2

(CH3)2CHCH=CH2

CH3CH=C(CH3)2

Branched-chain isomerism, positional isomerism, functional group isomerism

optical isomers

geometric isomers

6. (a) hex-3-ene: geometric isomerism

(b) 2-bromobutane: optical isomerism H

C H3C H2

C *

H

CH3

H3C

Br

C *

C H2C H3 Br

mi rror

(c) cyclobutane-1,2-dicarboxylic acid geometric isomerism

*

*

*

optical isomerism (for trans-isomer)

*

COOH

COOH

*

*

*

COOH

COOH mirror plane

(d) cyclohexene: none

*

(e) C6H5CH(OH)CH=CH2 optical isomerism

(f) CH3CH=CHCH2CH(OH)CH3 geometric & optical isomerism *

* H C* O H C H 2 = CH

HO

C* H CH =CH 2

mirror plane

m irr or p la n e

*

* mirror plane

8.

a. b. c. d. e. f. g. i.

electrophilic substitution addition/reduction/catalytic hydrogenation nucleophilic addition elimination free radical substitution elimination/dehydration hydrolysis 1st step: electrophilic addition 2nd step: nucleophilic substitution