Organic Chemistry

The Oxford School, Dubai

AS Chemistry Workbook

Topic – Organic chemistry

1

HC

O

H

1. Complete the table

Name Structure Examples & isomers Structural formula

Display formula

Alkanes C-C (all single

bonds) C4H10

Alkenes C=C (double

bonds) C3H6

Alcohols C-OH C4H10O

Aldehydes C4H8O

Ketones C4H8O

Acids C4H8O2

Esters C4H8O2

Amines

R-NH2 C3H9N (three types)

- Functional Groups - Structures and Nomenclature

Name Structure Examples & isomers Name Ending

IUPAC Name

Alkanes C4H10 Root

name

Alkenes C3H6

-ene

Alcohols C4H10O

-ol

Aldehydes C4H8O

-al

R - C - R

O

R - C - OH

O

R - C - OR

O




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Ketones C4H8O

-one

Acids C4H8O2

-oic acid

Esters C4H8O2 --yl

-oate

Amines C3H9N (three types) -yl

amine

2. Name the following compounds and write their skeletal formula and structural

formula.

(a)

CH3

CH3

H C

H

H

C

H

H

HCC

H

H

(b)

C C

H

H

H

H

C

H

H

CBr

H

(c)

C C C

H

H

HHH

H

C

H

H

(d)

C

H

H

CC

H

H

H

Cl HC

H

H

C

HHH




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3. Write the display formula of the following compounds.

a. CH3CH(CH3)CH3

b. CH3CHBrCH2Br

c. CH2=CHCH2CH3

d. CH3CH=C(CH3)CH3

4. Write the structural formula of the following compounds.

a. Methylbutane ………………………………………………..

b. but-1-ene………………………………………………………

c. 3-ethyl,2-methylhex-1-ene…………………………………….

d. 3-chlorobut-1-ene ………………………………………………..

e. 1,1-dichloropropane……………………………………………..

f. 2,2,4-trimethylheptane …………………………………………

g. pent-2-ene…………………………………………………………




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5. Name the following organic compounds:

CH3C

O

O CH2CH CH3

CH3

N

H

C2H5

C2H5

6. Draw displayed formulae for the following compounds:

a. 2-hydroxyethanamide

b. ethanoic butanoic anhydride

c. ethyl 2-hydroxypropanoate

d. N-methylbutanamide

e. N- methyl, N-ethyl, 2-aminobutane




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f. sodium 2-hydroxyethanoate

7.

8. P, Q and R have the molecular formula C6H12

All three are branched-chain molecules and none is cyclic. P can represent a pair of optical isomers. Q can represent a pair of geometrical isomers. R can represent another pair of geometrical isomers different from Q.

Draw one possible structure for one of the isomers of each of P, Q and R.

Structure of P

Structure of Q

Structure of R




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9. What is meant by a chiral compound?

................................................................................................................................ ................................................................................................................................

(a) But-2-ene, CH3CH=CHCH3, exists as geometric isomers. (i) Draw the geometric isomers of but-2-ene.

(ii) Explain how geometric isomerism arises. ......................................................................................................................

......................................................................................................................

(b) (i) Draw the structural formula of a compound which is an isomer of but-2-ene but which does not show geometric isomerism. (ii) Explain why the isomer drawn in (i) does not show geometric isomerism.

......................................................................................................................

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10. Name the alkene CH3CH2CH=CH2

........................................................................................................................

(i) Explain why CH3CH2CH=CH2 does not show geometrical isomerism.

........................................................................................................................

........................................................................................................................

(ii) Draw an isomer of CH3CH2CH=CH2 which does show geometrical

isomerism.




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(iii) Draw another isomer of CH3CH2CH=CH2 which does not show

geometrical isomerism.

11. Four of the structural isomers of C4H10O are alcohols. One of these isomers is

butan-2-ol. a. Draw the structural formula E of two other alcohols with molecular formula

C4H10O and name each of these isomers. Diagrams Isomer 1 Isomer 2 Name of isomer 1 Name of isomer 2

12. a) Explain the following terms and give an example of each.

i) Electrophile ………………………………………………………………………………………

………………………………………………………………………………………

ii) Nucleophile ………………………………………………………………………………………

……………………………………………………………………………………….

iii) Free radical ………………………………………………………………………………………

………………………………………………………………………………………




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b) Write the balanced equation to illustrate: i) Electrophilic addition

ii) Nucleophilic substitution

iii) Free-radical substitution

c) A chemical bond can be broken either by homolytic fission or by heterolytic fission. Explain , with the aid of suitable equations, what you understand by the terms homolytic fission and heterolytic fission. …………………………………………………………………………………………

…………………………………………………………………………………………

…………………………………………………………………………………………

…………………………………………………………………………………………

…………………………………………………………………………………………

13. But-2-ene and butan-2-ol both exhibit stereoisomerism.

a) Explain what is meant by the term stereoisomerism …………………………………………………………………………………………

…………………………………………………………………………………………

…………………………………………………………………………………………

b) Name the type of stereoisomerism shown by but-2-ene and butan-2-ol. …………………………………………………………………………………………

…………………………………………………………………………………………

…………………………………………………………………………………………

c) Using appropriate type of formulae, illustrate your answers to b for but-2-ene and butan-2-ol. Draw to structures of each type of isomerism.




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14. Draw all the possible structural isomers of C5H11Br (there are 8 in total). Label the isomers A – H and name them.

a) Identify two molecules which are positional isomers.

b) Identify two molecules which are chain isomers.

c) Identify two molecules which are chiral and draw the two optical isomers of each. Explain briefly how they could be distinguished. ……………………………………………………………………………………………

……………………………………………………………………………………………

……………………………………………………………………………………………

15. a) Draw the two possible structures of a molecule with molecular formula C4H8O2

and containing a carboxylic acid group. Name both of the isomers.

b)Draw four possible structures of molecules with the same molecular formula

but containing a different functional group. Name the functional group and the molecules containing it. What is the type of isomerism shown between these molecules and the molecules drawn in (a)?




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16. The alkanes form an homologous series of hydrocarbons. The first four straight-

chain alkanes are shown below. methane CH4

ethane C2H6

propane CH3CH2CH3

butane CH3CH2CH2CH3

a) State what is meant by the term hydrocarbon. b) Each homologous series has its own general formula. State two other

characteristics of an homologous series.

......................................................................................................................

......................................................................................................................

......................................................................................................................

c) Branched-chain structural isomers are possible for alkanes which have more than three carbon atoms. (i) State what is meant by the term structural isomers. ....................................................................................................................

....................................................................................................................

...................................................................................................................

(ii) Name the two isomers of hexane shown below.

Name ….................................................................

Name ...................................................................




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(iii)Give the structures of two other branched-chain isomers of hexane.

Isomer 3 Isomer 4

d) A hydrocarbon, W, contains 92.3% carbon by mass. The relative molecular mass of W is 78.0 (i) Calculate the empirical formula of W.

(iii) Calculate the molecular formula of W.

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Organic Chemistry