CHEMLAB FINAL EXAM

phenols

• Aromatic compounds containing one or more OH groups directly attached to benzene ring carbon

• most versatile and important organic chemical.

• acidic

phene

The term phenol is derived from an old name

of benzene which is

hydroxyl group

governs the solubility of phenol in water

hydrogen bonds

are formed between

water and phenol molecules which makes

phenol soluble in water.

LITMUS TEST

test whether the given solution is acidic or basic.

base

red litmus paper turns blue

acid

blue litmus paper turns red

FERRIC CHLORIDE TEST

- Aqueous solution of phenol + freshly prepared ferric chloride solution = violet or blue discoloration

Phenol, resorcinol,

Ortho cresol, Para

cresol

Violet or blue coloration

Cathecol

Green coloration

Hydroquinone

Violet or transient

blue color

Pyrogallol

Blue rapidly

changing to red

LIBERMANN’S TEST

• Phenol + concentrated sulfuric acid + sodium nitrite = yellow color quinone monoxime complex.

• excess phenol and sulfuric acid = deep blue indophenol complex

• diluted + sodium hydroxide = red color indophenol

BROMINE WATER TEST

bromine water + aqueous solution of phenol = white precipitate of tribromophenol

PHTALEIN DYE TEST

phenol + phtalic anhydride + sulfuric acid = colorless compound

phenolphtalein

colorless compound made out of phenol + phtalic anhydride + sulfuric acid

flourescein

phenolphtalein with dilute sodium hydroxide solution gives a pink color flourescent

Phenol

Reddish pink

o-cresol

Red

m-cresol

Blue or violet blue

1-naphthol

Green

2-naphthol

Faint green

Resorcinol

Yellow-green fluorescence

Hydroquinone

Deep purple

Infrared Phenols

O-H stretching in the same region, 3200 – 3600 cm, as alcohols.

Phenols for alcohol.

3200 – 3600 cm

Phnenolic ethers

do not show the O-H band but do show the C-O stretching.

Aryl and vinyl ethers

1200 – 1275 cm and weaker, 1020 – 1075 cm

Alkyl ethers,

1060 – 1150 cm

NMR

absorption by the O-H proton of a phenol, like

that of an alcohol, is affected by the degree of

hydrogen bonding and hence by the temperature,

concentration, and nature of the solvent.

CMR.

The OH of phenols exerts the usual effect of an

electronegativity substitute.

DNPH Test

- Aldehydes and ketones + 2,4 dinitrophenylhydrazine solution = yellow or red precipitation.

SODIUM BISULPHITE TEST

- Aldehydes and small methyl ketones + saturated Sodium Bisulphite Solution = crystalline white precipitate

TOLLEN’S TEST (SILVER MIRROR TEST)

aldehyde + tollen’s reagent + heat = silver mirror

FEHLING’S SOLUTION TEST

aliphatic aldehyde + fehling’s aldehyde and ketones + boil = brick red precipitate of cuprous oxide

BENEDICT’S SOLUTION TEST

aliphatic aldehyde + benedict’s solution + boil = brick red precipitate of cuprous oxide

SODIUM NITROPRUSSIDE TEST

Ketones + alkaline sodium nitroprusside solution dropwise = a wine red or orange red color

Ketones

the carbon atom in the carbonyl group is

bonded to two hydrocarbon groups.

polar

stronger intermolecular forces than hydrocarbons = higher boiling points

KETONES: SOLUBILITY

One of the slightly positive hydrogen atoms in a water molecule can be sufficiently attracted to one of the lone pairs on the oxygen atom of a ketone for a hydrogen bond to be formed.

PREPARATION

• 2° alcohols by oxidation

• Friedel-Crafts Acylation

Reduction

a. Lithium aluminium hydride (LiALH4)

b. Sodium borohydride (NaBH4)

c. Catalytic hydrogenation

Addition

nucleophilic addition of hydrogen cyanide

nucleophilic addition of sodium bisulphate

Condensation

• hydrazines

• hydroxlamine

• phenylhydrazine

• 2,4-dinitrophenylhydrazine

Reaction w/ Grignard Reagent

-A Grignard Reagent is a strong nucleophile

resembling a carbanion, R: attacks the

electrophilic carbonyl carbon atom to give an

alkoxide intermediate.

-Subsequent protonation gives alcohol.

Iodoform reaction

-When ketones containing methyl ketone

group + warmed + iodoform reagent =

yellow precipitate of triiodomethane is formed.

CARBOXYLIC ACID

Organic compounds which contain the carboxyl

functional group

carboxyl

derived from carbonyl (C=O)

and hydroxyl (OH) because in the carboxyl group

these two groups are directly bonded to each

other.

Carboxyl groups

classified as monocarboxylic acid, dicarboxylic acid, and tricarboxylic acid.

fatty acids.

long chain monocarboxylic acids

PREPARATION OF CARBOXYLIC ACID

1. Oxidation of Primary Alcohols and Aldehydes.

2. Oxidation of Alkenes

3. Hydrolysis Nitriles

4. Hydrolysis of Esters

5. Carboxylation of Grignard Method

6. Carboxylation of Alkenes

7. From Malonic Ester

Oxidation of Primary Alcohols and Aldehydes

o Primary alcohols and aldehydes on

oxidation with sodium or potassium

permanganate, give the corresponding

carboxylic acids.

Oxidation of Alkenes

o Alkenes react with basic potassium

permanganate under vigorous conditions

to produce carboxylic acid.

Hydrolysis Nitriles

o Nitriles give carboxylic acid

Hydrolysis of Esters

o When ester is boiled with concentrated

aqueous NaOH, and treatment with acid

to give carboxylic acid.

Carboxylation of Grignard Method

o Alkyl halide is first converted into

corresponding Grignard reagent and

allowed to react with carbon dioxide and

further hydrolysis to give carboxylic acid.

Carboxylation of Alkenes

o The alkene is heated with carbon

monoxide and steam under pressure at

300° - 400° in the presence of phosphoric

acid as the catalyst.

From Malonic Ester

o Alkyl halides are treated with sodium

derivative of diethyl malonate to give a

substituted malonic ester, and this

undergoes hydrolysis and decarboxylation

to give acid.