SEMESTER 3

CHEMISTRY

SEMESTER 3

CHEMISTRY

ORGANIC CHEMISTRY

Alkane

Alkene

Haloalkane

Hydroxyl compound

Carbonyl compound

Carboxyl compound

Amino compound

a) Alkane with halogen (X2)

General Equation : RCH2CH3 + X2 (g) → RCHXCH3 + HX

Reagent /Condition : chlorine or bromine gas ;

under ultraviolet light (UV)

Type of reaction : Free radical substitution reaction

Note :Note :

1. The rate of reaction is slow, therefore cannot be use as a test

to distinguish alkane from other compounds.

2. As long as it’s a saturated carbon, it can be halogenated via

free radical reaction. For example :

CH3NH2 + Br2 → BrCH2NH2 + HBr

b) i.Alkene with halogen (X2)

General equation : RCH=CH2 + X2 (g or l) → RCHXCH2X

Reagent /Condition : chlorine or bromine gas ;

under organic solvent CH2Cl2 or CCl4Type of reaction : electrophilic additional reaction

Note : 1. The rate of reaction is high, and therefore suitable to

be use to distinguish alkene from other functioning group.be use to distinguish alkene from other functioning group.

2. Reaction is slightly different when halogen its reacted as

aqueous solution. For example, when react with bromine water,

the following reaction take place :

RCH=CH2 + Br2 (aq) →

RCH(OH)CH2Br (major) + RCHBrCH2Br (minor)

*Note from the reaction, -OH is added to C with more substituent / Br is added

to C with more H

b) ii. Alkene with hydrogen halide (HX)

General equation :RCH=CH2 + HX (g) →

RCHXCH3 (major) + RCH2CH2X (minor)

Reagent /Condition : hydrogen chloride, HCl, hydrogen bromide,

HBr / room temperature

Type of reaction : electrophilic additional reactionType of reaction : electrophilic additional reaction

Note : 1. The reaction follows Markovnikoff rules - In addition of

hydrogen halide to unsaturated hydrocarbon, C=C, hydrogen is

preferable to be added to carbon with greater hydrogen in it.

c) Alcohol with PCl5 or thionyl chloride SOCl2General equation : RCH2OH + PCl5 → RCH2Cl POCl3 + HCl (g)

RCH2OH + SOCl2 → RCH2Cl + SO2 (g) + HCl (g)

Reagent /Condition : PCl5 in room temperature or

SOCl2 under reflux

Type of reaction : nucleophilic substitution reaction.Type of reaction : nucleophilic substitution reaction.

Note :1. Usually the reaction using thionyl chloride is more

preferable since the side products produces are gas, hence the

main organic product is easily isolated.

d) Carboxylic acid with PCl5 or SOCl2Equation : RCH2COOH + PCl5 → RCH2COCl + POCl3 + HCl (g)

RCH2COOH + SOCl2 → RCH2COCl + SO2 (g) + HCl (g)

Reagent /Condition : PCl5 in room temperature or

SOCl2 under refluxSOCl2 under reflux

Type of reaction : nucleophilic substitution reaction.

Note : 1. Usually the reaction using thionyl chloride is more

preferable since the side products produces are gas, hence the

main organic product is easily isolated.

e) Benzene (or any derivatives) with halogen

General equation :

Reagent /Condition : chlorine(Cl2) in AlCl3 at room temperature

bromine(Br2) in FeBr3 under refluxbromine(Br2) in FeBr3 under reflux

Type of reaction : electrophilic aromatic substitution reaction.

Note :1. The reaction uses AlCl3 or FeBr3 as catalyst in the

reaction

f) Phenol with bromine water

General equation :

Reagent /Condition : bromine water, Br2 (aq) under room temp

Type of reaction : electrophilic aromatic substitution reaction.

Note : 1. Observation of the reaction - brown solutionNote : 1. Observation of the reaction - brown solution

decolourised and turned to white precipitate when bromine water

is added to phenol

2. The reaction occur almost immediately since -OH in phenol is

ring activate, which caused all Br to substituted at all ortho and

para position.

g) Aniline with bromine water

General equation :

Reagent /Condition : bromine water, Br2 (aq) under room temperature

Type of reaction : electrophilic aromatic substitution reaction.Type of reaction : electrophilic aromatic substitution reaction.

Note :1. Observation of the reaction - brown solution decolourised and

turned to white precipitate when bromine water is added to aniline

2. The reaction occur almost immediately since -NH2 in aniline is ring

activate, which caused all Br to substituted at all ortho and para

position.

Homologous series

Chemical Tests

a)To distinguish alkene from other functioning group

i. Reagent / Condition : bromine in CCl4Observation : Brown colour of bromine decolourised while the other will not

Equation :

ii. Reagent / Condition : hot acidified KMnO4

Alkene

-C=C-

ii. Reagent / Condition : hot acidified KMnO4

Observation : Purple colour of KMnO4/H+ decolourised

while the other will not

Equation :

(Note : This test is also suitable to distinguish alk-1-ene with

other alkene. Both alkene will decolourised purple colour of

KMnO4 but alk-1-ene will further give effervescence that turned line water chalky)

Alcohol

-C-OH

a) To distinguish 1o, 2o alcohol from tertiary alcohol

i. Reagent : acidified KMnO4 ; under reflux

Observation : purple colour of KMnO4/H+ decolourised

when added to 10 or 2o alcohol, but no observablechanges to 3o alcohol.

Equation

ii. Reagent :acidified K2Cr2O7 under reflux

Observation : green colour of K2Cr2O7/H+ turned orange

when added to 10 or 2o alcohol, but no observablechanges to 3o alcohol.

-C-OHchanges to 3o alcohol.

Equation :

b) ~ Iodoform test.

i. Reagent : I2 /OH- under reflux

Observation : brown colour decolourised and give yellow

crystal precipitate when added to alcohol with -

CH(OH)CH3, while compound without methyl alcoholshows no observable changes

Equation :

Carbonyl

compoun

a)Distinguish carbonyl compound & other functioning group

i. Reagent / Condition : 2,4-dinitrophenylhydrazine

Observation : Orange precipitate is formed when carbonyl compound is added to 2,4-dinitrophenylhydrazine.

Equation :

compound

C=O

b) To distinguish between aldehyde and ketone

i. Reagent : Fehling solution [solution of complex of Cu2+]

Positive Test : only works for aldehyde (except benzaldehyde)

Observation : blue solution turns to red precipitate of Cu2O

Equation : red ppt.

ii. Tollens' reagent [solution of complex Ag(NH3)2]+]

Positive test : only work for aldehyde (except glucose)

Observation : colourless solution turn silver mirror

Equation : silver mirror

c) To distinguish between ethanal and other aldehyde / c) To distinguish between ethanal and other aldehyde /

alkan-2-one with other ketone. Reagent : (I2 + NaOH) Iodine in

sodium hydroxide

Only work for ethanal as it has methyl-carbonyl group

Observation : a yellow crystal of triiodomethane is observed

Equation :

CH3CH=O + 3 I2 + NaOH � CHI3 + HCOO–Na+ + 3 HIHI

Carboxylic acid

-COOH

a) To distinguish between carboxylic acid and otherfunctioning group

Reagent : sodium carbonate, Na2CO3 or sodiumbicarbonate, NaHCO3

Observation : effervescence occur, colourless gas evolved turn lime water chalky

Equation : 2 R-COOH + Na2CO3 �

2 R-COONa + CO2 (g) + H2O

R-COOH + NaHCO � R-COONa + CO (g) + H OR-COOH + NaHCO3 � R-COONa + CO2 (g) + H2O

Amine

R-NH2

a) To distinguish between primary amine and other class ofamine / functioning group

Reagent : NaNO2 + HCl / 0-5oC

Observation : effervescence occur, colourless gas evolved.

Equation : R-NH2 + NaNO2 + HCl �R-OH + N2 + H2O + NaCl

a) To distinguish between benzene and cycloalkane

Reagent / Condition : conc. HNO3 catalysed by conc H2SO4 under reflux

Observation : Yellow oily liquid is observed when mixed with benzene

Equation :

b) To distinguish between phenol and alkyl alcohol

+ HNO3conc. H2SO4

NO2

+ H2O

b) To distinguish between phenol and alkyl alcohol

Reagent / Condition : bromine water

Observation : brown colour decolourised and white precipitate is

formed almost immediately after the reaction

Equation :

c) To distinguish between phenylamine and alkyl amine

Reagent / Condition : bromine water

Observation : brown colour decolourised and white precipitate is

formed almost immediately after the reaction

a) CH3CH2CH2OH to CH3CH2CH2CH2NH2

b) CH3CH2CH2Br to CH3CH2CH(OH)COOH

c) CH3CH2COOH to CH3CH2CH2COOH

d) CH3CH2OH to CH3CH(OH)CH3

e) CH3CH2OH to CH3CH2CH2CH2CONHCH2CH3

Sn, HClCH3

NO2

Cl2, UV

CH3

OH

CH2Cl

OH

ethanolic

KCN

CH2CN

OH

1. LiAlH4

2. H3O+

CH2CH2NH2

OH