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🌳 Concept tree

Lesson 5→Hydrocarbon Derivatives – Alcohols and Phenols

├── Functional groups

├── Alcohols and phenols — the difference

├── Nomenclature of alcohols

├── Classification of alcohols

├── Ethanol — preparation

├── Denatured (methylated) alcohol — "red spirit"

├── Physical properties

├── Chemical properties of ethanol

├── Uses of alcohols

├── Phenols

├── Preparation

├── Physical properties

├── Chemical properties

└── Tests for phenol

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 1 / 16

Functional groups

In the past organic compounds were grouped by physical properties such as smell and taste, or by a few chemical properties.
With the progress of chemical analysis it became clear that the properties of a compound are controlled mainly by a particular group of atoms in its molecule, the functional group.
Functional group an atom or group of atoms, joined in a particular way, that forms part of the molecule and decides the characteristic chemical properties of the whole molecule.

Class	General formula	Functional group	Example
Alcohols	R–OH	hydroxyl –OH	methanol CH₃OH
Phenols	Ar–OH	hydroxyl –OH on a benzene ring	phenol C₆H₅OH
Ethers	R–O–R	ether –O–	dimethyl ether CH₃OCH₃
Aldehydes	R–CHO	aldehyde –CHO	ethanal CH₃CHO
Ketones	R–CO–R	carbonyl C=O	propanone (acetone) CH₃COCH₃
Carboxylic acids	R–COOH	carboxyl –COOH	ethanoic acid CH₃COOH
Esters	R–COO–R	ester –COO–	ethyl ethanoate CH₃COOC₂H₅
Amines	R–NH₂	amino –NH₂	ethylamine C₂H₅NH₂

Compounds with the same functional group belong to one homologous series and react similarly.

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 2 / 16

Alcohols and phenols — the difference

Both contain one or more hydroxyl (–OH) groups.
If the –OH is attached to an alkyl group (R–) the compound is an alcohol; if it is attached directly to a carbon of a benzene ring (aryl group, Ar–) it is a phenol.
Both may be viewed as alkyl/aryl derivatives of water (one H of H₂O replaced by R or Ar) or as hydroxyl derivatives of hydrocarbons.

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 3 / 16

Nomenclature of alcohols

Comparison aspect	Main idea	Keywords
Common system	the word "alcohol" is added after the name of the alkyl group: CH₃OH methyl alcohol C₂H₅OH ethyl alcohol	wordalcoholaddedafter
•	The prefix iso is used when the chain ends in a carbon bearing two methyl groups and one hydrogen: isopropyl alcohol (CH₃)₂CH–OH	prefixusedchainends
IUPAC system	take the longest chain containing the carbon that carries –OH change -e of the alkane to -ol and number from the end nearest the –OH put the number of the carbon holding –OH before the name	takelongestchaincontaining

Comparison aspect	Main idea	Example	Keywords
•	CH₃OH methanol C₂H₅OH ethanol CH₃CH₂CH₂OH 1-propanol (n-propyl alcohol) CH₃CH(OH)CH₃ 2-propanol (isopropyl alcohol)	—	CH₃OHmethanolC₂H₅OHethanol
The three alcohol isomers derived from pentane	1-pentanol 2-pentanol 3-pentanol (and there are others from branched chains	2-dimethyl-1-propanol)	pentanolothersbranchedchains
Other examples	(CH₃)₂CHCH₂OH 2-methyl-1-propanol 2-dimethyl-1-butanol is CH₃CH₂C(CH₃)₂CH₂OH isopentyl alcohol (CH₃)₂CHCH₂CH₂OH (3-methyl-1-butanol)	—	₂CHCH₂OHmethylpropanoldimethyl

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 4 / 16

Classification of alcohols

(a) According to the number of –OH groups

Comparison aspect	Main idea	Keywords
Monohydric	one –OH: CH₃OH C₂H₅OH	CH₃OHC₂H₅OH
Dihydric	two –OH: ethylene glycol HOCH₂CH₂OH (1 2-ethanediol)	ethyleneglycolHOCH₂CH₂OHethanediol
Trihydric	three –OH: glycerol (glycerine) HOCH₂–CH(OH)–CH₂OH (1 3-propanetriol)	threeglycerolglycerineHOCH₂
Polyhydric	more than three –OH: sorbitol (six –OH groups)	threesorbitolgroups
(b) According to the type of carbinol carbon	(the carbon carrying –OH) for monohydric alcohols	carryingmonohydricalcohols

Comparison aspect	Main idea	Example	Keywords
Primary (1°)	carbinol carbon is attached to one other carbon (and two H): R–CH₂OH	ethanol 1-propanol	carbinolcarbonattachedCH₂OH
Secondary (2°)	carbinol carbon is attached to two carbons (and one H): R₂CHOH	2-propanol 2-butanol	carbinolcarbonattachedcarbons
Tertiary (3°)	carbinol carbon is attached to three carbons (no H): R₃C–OH	2-methyl-2-propanol (tert-butyl alcohol). (Methanol the exception has the carbinol carbon attached to no carbon and is counted with the primary alcohols.)	carbinolcarbonattachedthree

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 5 / 16

Ethanol — preparation

Ethanol
C₂H₅OH
is the oldest organic compound prepared in industry
the ancient Egyptians made it by fermenting sugars and starches thousands of years ago.

Alcoholic fermentation. About 20 % of the world’s ethanol is made by fermenting starch and sugar materials (sugar cane, sugar beet, maize).
In Egypt it is made from molasses (the sugar-rich residue of sugar refining, containing sucrose), for instance at the Egyptian Sugar and Distillation Company (Hawamdeya).
Yeast is added:

C₁₂H₂₂O₁₁ (sucrose) + H₂O —(invertase enzyme of yeast)→ C₆H₁₂O₆ (glucose) + C₆H₁₂O₆ (fructose)
C₆H₁₂O₆ —(zymase enzyme)→ 2C₂H₅OH + 2CO₂
The resulting dilute alcohol (about 10–15 %) is concentrated by fractional distillation (about 95–96 % ethanol, a constant-boiling mixture with water).
2. Catalytic hydration of ethene. The main industrial method in petroleum-producing countries: ethene obtained by cracking petroleum fractions is hydrated with steam in the presence of dilute sulphuric or phosphoric acid:
CH₂=CH₂ + H₂O —(H₃PO₄ or dil. H₂SO₄, heat, pressure)→ CH₃CH₂OH
Ethanol is therefore called a petrochemical (made from petroleum).
Note ethene is the only alkene that gives a primary alcohol by hydration; other alkenes follow Markovnikov’s rule and give secondary or tertiary alcohols:
CH₃CH=CH₂ + H₂O → CH₃CH(OH)CH₃ (2-propanol, secondary)
(CH₃)₂C=CH–CH₃ + H₂O → (CH₃)₂C(OH)–CH₂CH₃ (2-methyl-2-butanol, tertiary)

3. General method: hydrolysis of alkyl halides. Heating an alkyl halide with aqueous alkali (KOH or NaOH) replaces the halogen with –OH:
R–X + KOH(aq) → R–OH + KX

CH₃CH₂Br + KOH → CH₃CH₂OH + KBr (primary alcohol)
CH₃CHBrCH₃ + KOH → CH₃CH(OH)CH₃ + KBr (secondary)
(CH₃)₃C–Br + KOH → (CH₃)₃C–OH + KBr (tertiary)
Ease of hydrolysis: R–Cl < R–Br < R–I (the weaker the C–X bond, the easier). So alkyl iodides are hydrolysed most easily.
Which halide for which alcohol? methanol ← CH₃X; 2-butanol ← 2-halobutane; 2-methyl-2-pentanol ← 2-halo-2-methylpentane.

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 6 / 16

Denatured (methylated) alcohol — "red spirit"

Pure ethanol (96 %) is highly taxed to discourage its use in alcoholic drinks (harmful to health and society).
Ethanol for fuel, solvent and industry is made cheaper by adding poisonous or ill-smelling substances that are very hard to remove: methanol (causes blindness and madness), pyridine (foul smell) and a coloured dye.
This is denatured alcohol (converted alcohol, red spirit; about 85 % ethanol, 5 % methanol, 1 % other additive plus colour/odour, rest water).
It is unfit and illegal to drink.

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 7 / 16

Physical properties

Alcohols are neutral, colourless compounds.
The first members are light liquids, completely miscible with water; the middle members are oily; the higher ones are waxy solids.
Compared with alkanes of similar molecular mass, alcohols have high boiling points and (the lower members) high solubility in water.
Both effects are due to the polar –OH group, which forms hydrogen bonds between alcohol molecules themselves and between alcohol and water molecules.
Boiling points ethanol 78.5 °C; ethylene glycol 197 °C.
As the number of –OH groups rises, the number of hydrogen bonds rises, and so do solubility and boiling point.
(Order of boiling point ethanol < ethylene glycol < glycerol < sorbitol.)

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 8 / 16

Chemical properties of ethanol

Four types of reaction are distinguished:
A. Reactions of the hydrogen of the –OH group

Comparison aspect	Main idea	Keywords
Reaction with active metals (Na, K)	ethanol is neutral to litmus but it shows weak acid character by reacting with sodium releasing hydrogen (which burns with a pop) and forming sodium ethoxide: 2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑ (The O–H bond is polar: the electron pair is displaced toward oxygen so the H can be replaced by metal.) Sodium ethoxide is hydrolysed by water reforming ethanol: C₂H₅ONa + H₂O → C₂H₅OH + NaOH. Methanol: 2CH₃OH + 2Na → 2CH₃ONa + H₂	ethanolneutrallitmusshows
Ester formation (with carboxylic acids)	alcohols react with acids to form esters and water. Labelling with heavy oxygen ¹⁸O showed the water comes from –OH of the acid and H of the alcohol: CH₃COOH + C₂H₅¹⁸OH ⇌ CH₃CO¹⁸OC₂H₅ + H₂O (¹⁸O ends in the ester not in the water). The reaction is reversible so concentrated H₂SO₄ is added (catalyst and dehydrating agent)	alcoholsreactesterswater

B. Reaction of the –OH group (substitution)

With halogen acids (HX) the –OH is replaced by X
e.g. ethanol with concentrated HCl in presence of ZnCl₂ (catalyst):

C₂H₅OH + HCl —(ZnCl₂)→ C₂H₅Cl + H₂O

Conversion back→C₂H₅Cl + KOH(aq) → C₂H₅OH + KCl.

C. Reactions of the carbinol group — oxidation

Alcohols are oxidised by acidified K₂Cr₂O₇ (orange → green) or KMnO₄ (violet colour disappears).
The oxidation removes hydrogen from the carbinol carbon, first giving an unstable gem-diol (two –OH on the same carbon) which loses water.

Comparison aspect	Main idea	Keywords
Primary alcohol → aldehyde → carboxylic acid	(two steps): CH₃CH₂OH —[O]→ CH₃CHO (ethanal) —[O]→ CH₃COOH (ethanoic acid vinegar odour) Experiment: heat 3 mL ethanol with an equal volume of acidified potassium dichromate in a water bath for about 10 minutes — the colour changes from orange to green and the smell of vinegar appears	stepsCH₃CH₂OHCH₃CHOethanal
Secondary alcohol → ketone	(one step): CH₃CH(OH)CH₃ —[O]→ CH₃COCH₃ (propanone acetone)	stepCH₃CHCH₃COCH₃propanone
Tertiary alcohol	no hydrogen on the carbinol carbon so it is not oxidised under these conditions	hydrogencarbinolcarbonoxidised
•	D. Reaction of the whole molecule — dehydration with conc. H₂SO₄	Reactionwholemoleculedehydration

At 180 °C (excess acid)one molecule of water is removed from one molecule of alcohol → alkene: C₂H₅OH → CH₂=CH₂ + H₂O.

At 140 °C (excess alcohol)one water molecule is lost from every two alcohol molecules → ether: 2C₂H₅OH → C₂H₅–O–C₂H₅ (diethyl ether) + H₂O.

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 9 / 16

Uses of alcohols

Comparison aspect	Main idea	Example	Keywords
Ethanol	solvent for oils fats resins making drugs paints polishes perfumes antiseptic/disinfectant (sterilising skin mouthwash) fuel mixed with gasoline in some countries (	Brazil) main component of denatured alcohol filling thermometers for very low temperatures (down to about −50 °C because its freezing point is very low −110 °C). Alcoholic drinks damage health (liver cirrhosis cancer of the stomach and oesophagus)	solventoilsfatsresins
Ethylene glycol (dihydric)	antifreeze in car radiators in cold countries hydraulic brake fluids (viscous) printing inks making polyethylene glycol and the polyester fibre Dacron photographic film recording tapes	—	antifreezeradiatorscoldcountries
Glycerol (trihydric)	moisturiser in creams and cosmetics softens textiles manufacture of the explosive nitroglycerine (glyceryl trinitrate): C₃H₅(OH)₃ + 3HNO₃ —(conc. H₂SO₄)→ C₃H₅(ONO₂)₃ + 3H₂O Nitroglycerine in very small safe doses is also used to widen arteries in heart treatment	—	moisturisercreamscosmeticssoftens

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 10 / 16

Phenols

Comparison aspect	Main idea	Keywords
Phenols	are hydroxy-aromatic compounds in one or more –OH groups are attached directly to carbon atoms of a benzene ring: phenol C₆H₅OH (hydroxybenzene) 3-trihydroxybenzene (pyrogallol) 4-trihydroxybenzene	hydroxyaromaticcompoundsgroups
Phenol (carbolic acid), C₆H₅OH	has great industrial importance as the starting material of plastics (bakelite) dyes disinfectants salicylic acid derivatives (aspirin) and picric acid	greatindustrialimportancestarting

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 11 / 16

Preparation

From coal tar by fractional distillation.
with sodium hydroxide at high temperature and very high pressure (about 300 atm), giving sodium phenoxide which is acidified:
C₆H₅Cl + 2NaOH (≈ 300 °C, 300 atm) → C₆H₅ONa + NaCl + H₂O
C₆H₅ONa + HCl → C₆H₅OH + NaCl

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 12 / 16

Physical properties

A colourless, corrosive (caustic) solid with a characteristic odour, m.p. 43 °C.
It is sparingly soluble in cold water; solubility rises with temperature and it is completely miscible with water above 65 °C.

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 13 / 16

Chemical properties

1. Acidity — phenol compared with alcohols. Both react with sodium metal releasing hydrogen:
2C₆H₅OH + 2Na → 2C₆H₅ONa + H₂↑ ; 2ROH + 2Na → 2RONa + H₂↑.
But only phenol reacts with sodium hydroxide solution (alcohols do not): C₆H₅OH + NaOH → C₆H₅ONa + H₂O (sodium phenoxide).
Hence phenol is called carbolic acid.
The benzene ring withdraws electrons from the oxygen of the O–H group, which makes the O–H bond more polar, longer and weaker, and so the proton leaves more easily. (Phenol is still a weak acid – weaker than carboxylic acids and even carbonic acid.)

Reaction with halogen acids. In alcohols the –OH can be replaced by X with HX.
In phenol the C–O bond is shorter and stronger (the oxygen lone pair interacts with the ring), so the –OH cannot be replaced by halogen acids; phenol does not react with HCl.
Phenol with concentrated nitric acid in the presence of concentrated sulphuric acid gives 2,4,6-trinitrophenol (picric acid):
C₆H₅OH + 3HNO₃ —(conc. H₂SO₄)→ C₆H₂(NO₂)₃OH + 3H₂O
Picric acid is an explosive and is used in treating burns; it stains the skin yellow for several days (until the outer skin layer is renewed).
In acidic or basic medium phenol reacts with methanal (formaldehyde, HCHO): one molecule of methanal joins two molecules of phenol with loss of water; the units keep joining by condensation polymerisation to form a three-dimensional network polymer, Bakelite. Condensation polymers are formed from two kinds of monomers with elimination of a small molecule such as H₂O. Bakelite is a dark-brown thermosetting plastic (it does not soften again on heating), heat-resistant and a good electrical insulator — used for electrical fittings, switches, handles and ash trays.

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 14 / 16

Tests for phenol

Few drops of iron(III) chloride solution → a violet colour.
→ a white precipitate (2,4,6-tribromophenol).

(Ethanol, by contrast, gives no colour with FeCl₃ and no precipitate with bromine water; its detection uses the acidified dichromate test of Lesson 10.)
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Part 16

📖

🔍 In-Depth Explanations, Deductions & Multi-Book Insights:

Chemistry Thanaweya Amma (2026/2027)

Lesson 5 – Hydrocarbon Derivatives – Alcohols and Phenols
Detailed Academic Lesson Overview:
Alcohols and phenols contain the hydroxyl group (-OH).
Alcohols are aliphatic derivatives classified as primary (1°), secondary (2°), or tertiary (3°) based on carbinol carbon connectivity.
Phenols are aromatic derivatives where -OH is bonded directly to the benzene ring.

🌳 Hierarchy Classification & Conceptual Roadmap

Alcohols and Phenols Chemistry

├── 1. Classification of Alcohols

Comparison aspect	Main idea	Keywords
│ ├── Monohydric	1° (Ethanol) 2° (Isopropanol) 3° (2-methyl-2-propanol)	EthanolIsopropanolmethylpropanol
│ ├── Dihydric	Ethylene glycol Trihydric: Glycerol Polyhydric: Sorbitol Glucose	EthyleneglycolTrihydricGlycerol
│ └── Industrial Manufacture of Ethanol	Fermentation of Molasses (Sucrose) or Hydration of Ethene	FermentationMolassesSucroseHydration
•	├── 2. Chemical Oxidation of Alcohols (using acidified K₂Cr₂O₇ or KMnO₄)	ChemicalOxidationAlcoholsusing
│ ├── Primary (1°)	Oxidizes in 2 steps: Alcohol → Aldehyde → Carboxylic acid	OxidizesstepsAlcoholAldehyde
│ ├── Secondary (2°)	Oxidizes in 1 step: Alcohol → Ketone	OxidizesstepAlcoholKetone
│ └── Tertiary (3°)	Does NOT oxidize under ordinary conditions (no H on carbinol C)	Doesoxidizeunderordinary

└── 3. Phenols (Carbolic Acid C6H5OH)

Comparison aspect	Main idea	Keywords
├── Acidity of Phenol	Strongly more acidic than alcohols due to benzene ring drawing electrons weakening O-H bond	Stronglyacidicalcoholsbenzene
├── Reactions	Reacts with NaOH to form sodium phenoxide (alcohols DO NOT react with NaOH)	ReactsNaOHformsodium
•	└── Diagnostic Tests for Phenol	DiagnosticTestsPhenol
•	├── Addition of FeCl₃ solution produces a deep violet coloration	AdditionFeCl3solutionproduces
•	└── Addition of bromine water produces a white precipitate of 2 6-tribromophenol	Additionbrominewaterproduces
•	📋 Master Teacher's Blackboard Rules & Exam Secrets	MasterTeacherBlackboardRules
RULE 1	Tertiary alcohols resist oxidation with acidified dichromate because their carbinol carbon is attached to zero hydrogen atoms	Tertiaryalcoholsresistoxidation
RULE 2	Phenols are significantly more acidic than alcohols (hence called Carbolic acid). Both react with active sodium metal but ONLY phenols react with aqueous NaOH alcohols DO NOT react with NaOH	Phenolssignificantlyacidicalcohols
RULE 3	Diagnostic test for suspected drunk drivers: Breathing into a tube containing acidified potassium dichromate impregnated on silica gel breath containing alcohol vapors changes the color from orange to green	Diagnostictestsuspecteddrunk
📊 Detailed Comparison Matrix	Comparative Analysis: Aliphatic Alcohols vs. Aromatic Phenols	ComparativeAnalysisAliphaticAlcohols

Property / Reaction	Aliphatic Alcohol (e.g., Ethanol)	Aromatic Phenol (Carbolic Acid)
Reaction with Sodium (Na)	Reacts evolving H₂ gas	Reacts evolving H₂ gas
Reaction with Aqueous NaOH	NO reaction (Weak acidity)	Reacts forming Sodium phenoxide + H₂O
Reaction with Conc. HCl	Reacts forming alkyl chloride + H₂O	NO reaction (C-O bond is extremely strong)
Addition of Neutral FeCl₃	No visible change	Produces distinct deep violet coloration
Addition of Bromine Water	No visible change	Produces white ppt (2,4,6-tribromophenol)

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols · 16 / 16

Curriculum

Chemistry

Chapter 1 - Transition Elements and Iron Metallurgy

Chapter 2 - Chemical Analysis

Chapter 3 - Chemical Equilibrium

Chapter 4 - Electrochemistry

Chapter 5 - Organic Chemistry

More lessons

Lesson 5: Hydrocarbon Derivatives – Alcohols and Phenols

🌳 Concept tree

├── Functional groups

├── Alcohols and phenols — the difference

├── Nomenclature of alcohols

├── Classification of alcohols

├── Ethanol — preparation

├── Physical properties

├── Chemical properties of ethanol

├── Uses of alcohols

├── Phenols

├── Preparation

├── Physical properties

├── Chemical properties

└── Tests for phenol

B. Reaction of the –OH group (substitution)

C₂H₅OH + HCl —(ZnCl₂)→ C₂H₅Cl + H₂O

C. Reactions of the carbinol group — oxidation

🔍 In-Depth Explanations, Deductions & Multi-Book Insights:

Chemistry Thanaweya Amma (2026/2027)

🌳 Hierarchy Classification & Conceptual Roadmap

Alcohols and Phenols Chemistry

├── 1. Classification of Alcohols

└── 3. Phenols (Carbolic Acid C6H5OH)

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