Alcohols: Properties, Preparation & Reactions - Chemistry Class 12 - NEET

What are Alcohols? 

Alcohols are a class of organic compounds characterized by the presence of one or more hydroxyl (-OH) functional groups attached to a carbon atom. They are commonly used as solvents, fuels, and beverages.

• In the chemical structure of an alcohol, the hydroxyl group (-OH) is attached to a carbon atom, which may be part of a larger hydrocarbon chain or a ring structure. 
• The general formula for an alcohol is R-OH, where R represents the hydrocarbon group.
• The major simple forms of alcohol include methanol (CH₃OH), ethanol (C₂H₅OH), propanol (C₃H₇OH) and butanol (C₄H₉OH).

Types of Alcohols: Classification and Descriptions

Alcohols can be classified into different types based on various factors such as the structure of the hydrocarbon group, the number of hydroxyl groups, and the position of the hydroxyl group in the carbon chain.

Here are some common types of alcohols and their classifications:

1. Classification on the Basis of number of Carbon Atoms attached to Carbon bonded with the -OH group

Depending on the number of carbon atoms which are directly attached to the carbon that is bonded with the -OH group, alcohols can be classified into three types.

• Primary Alcohols: These alcohols have one hydroxyl group (-OH) attached to a primary carbon atom (a carbon atom directly bonded to only one other carbon atom). Example: Ethanol 
• Secondary alcohols: These alcohols have one hydroxyl group (-OH) attached to a secondary carbon atom (a carbon atom directly bonded to two other carbon atoms). Example: Isopropanol 
  
  Isopropanol

• Tertiary alcohols: These alcohols have one hydroxyl group (-OH) attached to a tertiary carbon atom (a carbon atom directly bonded to three other carbon atoms). Example: tert-Butanol 
  tert-Butanol 

2. Classification on the number of hydroxyl groups attached,

• Monohydric alcohols: They contain one -OH group. Example, Ethanol
• Dihydric alcohols: They contain two -OH groups. Example, Ethan-1,2-diol.
• Trihydric alcohols: They contain three -OH groups. Example, Propane- 1,2,3-triol

Mono, Di &Trihydric Alcohols

3. Aromatic Alcohols: 

Depending on the number of hydroxyl groups attached, phenols can be classified into three types.

• Monohydric phenols: They contain one -OH group.
• Dihydric phenols: They contain two -OH groups. They may be ortho-, meta- or para- derivative.
• Trihydric phenols: They contain three -OH groups.

Classification of Phenols

4. Allylic Alcohols:

Example: Allyl alcohol (CH₂=CHCH₂OH).
Allyl Alcohol

5. Benzyl Alcohols:

Example: Benzyl alcohol (C₆H₅CH₂OH).
Benzyl Alcohol

What are the Properties of Alcohols?

The physical and chemical properties of alcohols are mainly due to the presence of hydroxyl group.

Some important physical and chemical properties of alcohols are given below:

Physical Properties of Alcohols

1. The Boiling Point of Alcohols
Alcohols generally have higher boiling points in comparison to other hydrocarbons having equal molecular masses.
Ethanol has a higher Boiling Point than Ethane

• Intermolecular Hydrogen Bonding: Alcohols have higher boiling points due to hydrogen bonding between hydroxyl groups.
  
  Hydrogen Bonding in Ethanol
• Carbon Chain Length: Boiling points of alcohols increase with longer aliphatic carbon chains.
• Branching in Carbon Chains: Increased branching leads to lower boiling points in alcohols.
• Primary Alcohols: Primary alcohols have higher boiling points compared to other types.

2. Solubility of Alcohols in Water

The solubility of alcohol in water is governed by the hydroxyl group present. The hydroxyl group in alcohol is involved in the formation of intermolecular hydrogen bonding. 

• Thus, hydrogen bonds are formed between water and alcohol molecules which make alcohol soluble in water.
  
  Intermolecular H bond between water & alcohol molecules
• However, the alkyl group attached to the hydroxyl group is hydrophobic in nature. Thus, the solubility of alcohol decreases with the increase in the size of the alkyl group.

3. Density: 

• Alcohols have densities lower than that of water, meaning they float on water. 
• The density of alcohols increases with an increase in carbon chain length and molecular mass.

4. Odor:

• Many alcohols have distinct odors. For example, ethanol has a characteristic alcoholic smell.
• The odor of alcohols can vary depending on the carbon chain length and any additional functional groups present.

5. Volatility: 

• Alcohols generally have higher volatility compared to water and many other compounds.
• The volatility decreases as the carbon chain length increases, resulting in longer evaporation times.

6. Flammability:

• Alcohols are flammable substances with varying degrees of flammability depending on their molecular structure.
• Lower-molecular-weight alcohols, such as methanol and ethanol, are highly flammable and can be used as fuel sources.

Chemical Properties of Alcohols

1. Oxidation Reactions of Alcohol

• Alcohols can undergo oxidation reactions to form various functional groups.
• Primary alcohols can be oxidized to aldehydes and further to carboxylic acids.
• Secondary alcohols can be oxidized to ketones.
• Tertiary alcohols, lacking a hydrogen atom attached to the carbon bearing the hydroxyl group, are resistant to oxidation.
  

2. Acidity of alcohols and their ability to undergo acid-base reactions.

Alcohols, in their pure form, are considered weak acids compared to strong mineral acids such as hydrochloric acid or sulfuric acid. The acidity of alcohols arises from the presence of the hydroxyl (-OH) group, which can donate a proton (H+) in acid-base reactions.

• Acid-Base Reaction: Alcohols can undergo acid-base reactions by donating a proton (H+) from the hydroxyl group. In this reaction, the alcohol acts as an acid, and the species accepting the proton acts as a base. The base can be another molecule or an ion, such as water (H₂O) or a hydroxide ion (OH-).
• Acidic Character: The acidity of alcohols is influenced by factors such as the nature of the alcohol, the structure of the molecule, and the stability of the resulting ion. Factors such as electron-withdrawing groups (-COOH, -NO₂) or resonance effects can enhance the acidity of alcohols.
  
• Acidic Strength: lcohols exhibit a range of acidic strengths, with phenols being more acidic than aliphatic alcohols. Phenols (aromatic alcohols) are more acidic due to the stabilization of the resulting phenoxide ion through resonance within the aromatic ring.
  
  Phenol more Acidic due to Resonance 
• Reaction with Strong Bases: Alcohols can react with strong bases, such as alkali metal hydroxides (e.g., sodium hydroxide, NaOH), to form alkoxide ions.

  The reaction involves the deprotonation of the alcohol's hydroxyl group, resulting in the formation of an alkoxide ion and water.

3. Dehydration of Alcohols:

• Alcohols can undergo dehydration reactions, eliminating a molecule of water.
• This typically occurs in the presence of heat and a dehydrating agent, such as concentrated sulfuric acid or phosphoric acid.
• Dehydration of alcohols leads to the formation of alkenes, resulting in the loss of the hydroxyl group.

4. Esterification Reaction:

• Alcohols can also undergo esterification reactions, where they react with carboxylic acids in the presence of an acid catalyst.
• In this reaction, the hydroxyl group of the alcohol combines with the carboxylic acid, resulting in the formation of an ester and water.

5. Reaction with Metals:

• Some alcohols can react with highly reactive metals, such as sodium or potassium, to produce alkoxides and hydrogen gas.
• This reaction is often used in organic synthesis to convert alcohols into alkoxide salts, which can participate in further reactions.

6. Reaction with Acid Chlorides:

• Alcohols can react with acid chlorides to form esters.
• This reaction, known as the Fischer esterification, involves the substitution of the chloride group in the acid chloride with the alkoxyl group of the alcohol.

7. Nucleophilic Substitution:

• Alcohols can act as nucleophiles in substitution reactions.
• They can undergo nucleophilic substitution with various electrophiles, such as alkyl halides or acyl chlorides, to form new organic compounds.

Preparation of Alcohols or Alcohol Synthesis

The preparation of alcohols refers to the methods or processes used to produce alcohol compounds. There are several common methods for the preparation of alcohols, each with its own specific conditions and reagents. Another term often used to describe the preparation of alcohols is "alcohol synthesis" or "alcohol formation." 

Here are some common methods for the preparation of alcohols:

1. Preparation of Alcohols From Alkenes

(a) By acid-catalyzed hydration of alkenes

• One method to prepare alcohols from alkenes is through acid-catalyzed hydration. 
• This process involves the addition of water to the double bond of the alkene in the presence of an acid catalyst. During the reaction, a carbocation intermediate is formed. 

Hydration of Alkenes with Acid Catalyst

• The addition of water follows Markovnikov's rule, where the hydrogen atom attaches to the carbon atom with the greater number of hydrogen atoms already attached. 

Mechanism of addition of water to alkenes to from Alcohols

• It's important to note that rearrangement of the carbocation can occur, leading to the formation of different alcohol products.     

(b) By Oxymercuration - Demercuration Process 
Alkenes react with mercuric acetate in presence of H₂O and tetrahydrofuran to give alkyl mercury compounds. This is one of the most common types of methods to prepare alcohols. This method always leads to anti Markovnikov’s addition of water to alkenes.

Formation of Alcohol by Oxymercuration - Demercuration Process

(c) By Hydroboration-oxidation process
Alkenes, when treated with diborane, give alkyl boranes, R₃B. Alkylboranes on oxidation with alkaline hydrogen peroxide give alcohol. It is significant to note that this method always leads to anti Markovnikov’s addition of water to alkenes.

Formation of Alcohol by Hydroboration-Oxidation process

(d) Hydroformylation of Alkenes (Oxo Reaction)

Lower molecular weight alkenes react with carbon monoxide and hydrogen in the presence of a catalyst in a reaction called hydroformylation or the oxo reaction. The resulting aldehyde is subsequently hydrogenated to form an alcohol.

Hydroformylation of Alkenes

2. Preparation of Alcohols From Alkyl Halides

(a) Hydrolysis of Halides

The hydrolysis of alkyl halides involves the reaction of the alkyl halide with an aqueous solution of an alkali hydroxide, typically sodium hydroxide (NaOH) or potassium hydroxide (KOH). This reaction is a nucleophilic substitution mechanism, where the halide ion (X^-) is replaced by the hydroxide ion (OH-), resulting in the formation of an alcohol.

The general reaction equation for the hydrolysis of alkyl halides is:
R-X + KOH → R-OH + KX
e.g. (CH₃)₂CHCH₂CH ₂-Br  (CH₃)₂CHCH₂CH ₂- OH
Here, R represents the alkyl group, and X represents the halide (such as chloride, bromide, or iodide).
Nucleophilic substitution reactions for the formation of alcohols can take place through 2 mechanisms:
(a) By S_N² Mechanism (Second-Order Substitution)
(b) By S_N¹ mechanism (first-order substitution) 
Here is a brief explanation of both of these:

S_N¹ Mechanism: It's a two-step process observed in reactions with tertiary and some secondary alkyl halides. First, the alkyl halide forms a carbocation intermediate. Then, a nucleophile attacks the carbocation, resulting in a mixture of stereoisomers.  Given below is the detailed explanation: 

S_N¹ Mechanism for formation of alcohols

S_N² Mechanism: It's a single-step process observed in reactions with primary and some secondary alkyl halides. The nucleophile simultaneously attacks the electrophilic carbon and displaces the leaving group, causing inversion of configuration at the chiral center.

S_N² Mechanism

3. Preparation of Alcohols From Grignard Reagent

(a) From air

• A Grignard reagent may be used to synthesize an alcohol by treating it with dry oxygen and decomposing the product with acid :

General reaction:

RMgX  RO₂MgX  2ROMgX  2ROH

e.g. C₂H₅MgBrC₂H₅O₂ MgX2C₂H₅OMgX 2C₂H₅OH MgBr(OH)

(b) From ethylene oxide

• The addition of Grignard reagent to ethylene oxide gives primary alcohol (with two carbon atoms added).

General reaction:

  RCH₂CH₂OMgX  RCH₂CH₂OH + MgX(OH)

e.g.  + C₂H₅MgBr  C₂H₅CH₂CH₂OMgBr  + MgBr(OH)

(c) From carbonyl compounds

• Alcohols can be synthesized from carbonyl compounds through nucleophilic addition reactions using Grignard's reagent. Grignard's reagent is an organometallic compound consisting of a carbon-metal bond, commonly formed by reacting an alkyl or aryl halide with magnesium metal.

(i) Addition of formaldehyde gives primary alcohol

General reaction:
= O RMgX RCH₂-OH

(ii) Addition to an aldehyde (other than formaldehyde) gives secondary alcohol

General reaction:

 (sec-alcohol)

e.g.  +  

(iii) Addition to a ketone gives tertiary alcohol. 

General reaction:

e.g. CH₃CH₂MgCl +  

(iv) Addition to an acid halide or an ester gives tertiary alcohol.

• Esters on treatment with Grignard's reagent first form ketones which then react with the second molecule of Grignard's reagent and form tertiary alcohol.

General reaction:

4. By Reduction of Carbonyl Compounds

(a) Catalytic hydrogenation of aldehydes and ketones
One method of synthesizing alcohols from carbonyl compounds is through catalytic hydrogenation of aldehydes and ketones. This process involves the use of a catalyst, typically a transition metal catalyst, and hydrogen gas (H₂) to reduce the carbonyl group to an alcohol.

General reaction: 

e.g. CH₃CHO + 2H  CH₃CH₂OH

e.g.  CH₃CH₂CH₂OH

_e.g.  + 4H

(b) Lithium Aluminium Hydride reduction of aldehydes and ketones
Another method for synthesizing alcohols from carbonyl compounds is through the reduction of aldehydes and ketones using lithium aluminum hydride (LiAlH₄). LiAlH₄ is a powerful reducing agent that can selectively convert carbonyl groups into alcohols.

General reaction:

(i)

(ii)

(iii) RCOOH+ 4H  RCH₂OH + H₂O

(iv)  RCH₂OH+ HCl

(v)  R-CH₂OH +R'OH

e.g.  CH₃CH₂OH

e.g.  C₂H₅CH₂OH +HCl

Question. Identify (X) in the following reaction:

X

Ans.

(c) NaBH₄ (Sodium Borohydride) reduction of aldehydes and ketones

• Another method for the synthesis of alcohols from carbonyl compounds is through the reduction of aldehydes and ketones using sodium borohydride (NaBH₄). NaBH₄ is a mild and selective reducing agent that is commonly used for this purpose.
• It is insoluble in ether and is used in an aqueous ethanolic solution to reduce carbonyl compounds. It does not reduce esters and acids.

 R-CH₂-OH

e.g. 

e.g. CH=CHCHO +4H  CH₃CH=CHCH₂OH

Note: Reduction of a ketone gives secondary alcohol

(d) Bouveault-Blanc Reduction
The reduction of aldehydes, ketones or esters by means of excess of sodium and ethanol or n-butanol as the reducing agent.

General reaction:

(i) Aldehyde  RCHO RCH₂OH

(ii) Esters  R'CO₂R'' R'CH₂OH R''OH

(iii) Ketones  R₂CO R₂CHOH

The Bouveault-Blanc reduction is believed to occur in steps involving transfer of one electron at a time.

Mechanism:

e.g. CH₃CHO +2H CH₃CH₂OH

e.g. CH₃COOC₂H₅ +4H2CH₃CH₂OH

e.g. 

5. By Reaction of Nitrous Acid on Aliphatic Primary Amines

The reaction of nitrous acid (HNO₂) with aliphatic primary amines (R-NH₂) leads to the formation of alcohols. This process is known as the nitrous acid reaction or nitrosation reaction.

General reaction: R-NH₂ + HONO  R-OH +N₂  + H₂O

Mechanism:

R-NH₂ (R)  ROH +N₂ +

e.g. (i) C₂H₅NH₂ +HNO₂ C₂H₅OH+ N₂ + H₂O

(ii) CH₃-CH₂- +HONO  CH₃-CH₂-+ N₂ +H₂O

Mechanism:

6. Formation of diols by Hydroxylation

Converting an alkene to a glycol requires adding a hydroxy group to each end of the double bond. This addition is called hydroxylation of the double bond.

(a) Syn hydroxylation, using KMnO₄ / NaOH or using OsO₄/H₂O₂

_{Syn hydroxylation is a chemical reaction that introduces hydroxyl (-OH) groups onto an unsaturated compound, typically an alkene. It is commonly achieved using two different reagent systems: potassium permanganate (KMnO4) with sodium hydroxide (NaOH), or osmium tetroxide (OsO4) with hydrogen peroxide (H2O2).}

General reaction :

e.g. 

(b) Anti hydroxylation, using peracids

Anti-hydroxylation is a chemical reaction that introduces hydroxyl (-OH) groups onto an unsaturated compound, specifically an alkene, in an anti-addition manner. One common method for achieving anti-hydroxylation is by using peracids, which are peroxy acids

Other Important Chemical Reactions of Alcohols

1. Reaction of Alcohols with Hydrogen Halides

When alcohols react with hydrogen halides (such as hydrogen chloride, HCl, or hydrogen bromide, HBr), they undergo a substitution reaction known as an alcohol halogenation reaction. The reaction involves the replacement of the hydroxyl (-OH) group of the alcohol with a halogen atom (-X).

Here is the general reaction and mechanism involved: 

General reaction:

R - OH + HX  R - X + H₂O (R may rearrange)

Reactivity of HX : Hl > HBr > HCl

Reactivity of ROH: allyl > benzyl > 3^o > 2^o > 1^o

Mechanism:
R - OH  R- R-X

e.g.

e.g.

e.g.

2. Reaction of Alcohols with Phosphorus Trihalides

• When alcohols react with phosphorus trihalides (such as phosphorus trichloride, PCl₃, or phosphorus tribromide, PBr3), they undergo a substitution reaction known as an alcohol phosphorane reaction. The reaction involves the replacement of the hydroxyl (-OH) group of the alcohol with a halogen atom (-X) and the formation of a phosphorus-containing group.
• Phosphorus halides produce good yields of most primary and secondary alkyl halides, but none works well with ter. alcohols. The two phosphorus halides used most often are PBr₃ and the P₄ / I₂ combination.

General reaction:

3R - OH + PX₃ 3R - X + H₃PO₃ 

Mechanism:

The mechanism for the reaction involves attachment of the alcohol group on the phosphorus atom, displacing a bromide ion and forming a protonated alkyl dibromophosphite (see the following reaction).

In a second step a bromide ion acts as a nucleophile to displace HOPBr₂, a good leaving group due to the electronegative atoms bonded to the phosphorus.

 RCH₂X  +  HOPX₂

e.g.  

e.g. 

3. Reaction of Alcohols with Thionyl Chloride

When alcohols react with thionyl chloride (SOCl₂), they undergo a substitution reaction known as an alcohol chlorination reaction. The reaction involves the replacement of the hydroxyl (-OH) group of the alcohol with a chlorine atom (-Cl) and the formation of sulfur dioxide gas (SO₂) as a byproduct.

The general equation for the reaction of alcohols with thionyl chloride is:

ROH + SOCl₂ → RCl + SO₂ + HCl

where ROH represents the alcohol, SOCl₂ represents thionyl chloride, RCl represents the alkyl chloride product, SO₂ represents sulfur dioxide, and HCl represents hydrogen chloride.

4. Dehydration of Alcohols

Dehydration of alcohols is a chemical reaction in which water (H₂O) is removed from the alcohol molecule, resulting in the formation of an alkene or an alkyne. This process involves the loss of a hydroxyl (-OH) group from the alcohol and a hydrogen atom from an adjacent carbon atom.

The general equation for the dehydration of an alcohol is
ROH → R-alkene + H₂O

Mechanism 

Step 1 :

Step 2 :

Step 3 :

The reaction mechanism for the dehydration of alcohols can vary depending on the type of alcohol involved: primary (1°), secondary (2°), or tertiary (3°) alcohol.
Reactivity of ROH : 3º > 2º > 1º

5. Reaction of Alcohols with Metals

The reaction of alcohols with metals can vary depending on the specific metal and conditions involved. In general, the reaction between alcohols and metals can result in the formation of metal alkoxides and hydrogen gas. Here are a few examples:

e.g.  

e.g. 

e.g. 

6. Ester Formation from Alcohols

Ester formation is a common reaction that involves the reaction between an alcohol and a carboxylic acid or its derivative. This reaction is known as esterification and results in the formation of an ester compound, along with the production of water as a byproduct.

General reaction: 

  +  + H₂O

e.g. CH₃CH₂O - H +   + H₂O

e.g.  +

7. Oxidation Reactions of Alcohols

Oxidation reactions of alcohols involve the conversion of alcohol functional groups (-OH) into carbonyl groups (C=O). The degree of oxidation depends on the type of alcohol and the oxidizing agent used. There are three main types of alcohols: primary (1°), secondary (2°), and tertiary (3°), and each reacts differently with oxidizing agents.

(a) Oxidation of primary alcohols

Primary alcohols can undergo two levels of oxidation, depending on the reaction conditions and the oxidizing agent used.

• Aldehyde formation: Under controlled oxidation conditions, primary alcohols can be oxidized to aldehydes. Common oxidizing agents for this level of oxidation include pyridinium chlorochromate (PCC), Collins reagent, or selective oxidation methods. The reaction is often carried out under mild conditions to avoid further oxidation to carboxylic acids.
  Alcohol to aldehyde: R-CH₂OH → R-CHO + H₂O
• Carboxylic acid formation: With stronger oxidizing agents, such as potassium permanganate (KMnO₄) or chromium trioxide (CrO₃) in acidic conditions, primary alcohols can be further oxidized to carboxylic acids.
  Alcohol to carboxylic acid: R-CH₂OH → R-COOH + H₂O

(b) Oxidation of secondary alcohols

Secondary alcohols can be oxidized to ketones by a variety of oxidizing agents, including chromic acid (H₂CrO₄), potassium dichromate (K₂Cr₂O₇₎ in acidic conditions, or pyridinium dichromate (PDC). The reaction is typically performed under acidic conditions to facilitate the formation of the carbonyl group without further oxidation to carboxylic acids.

The general equation for the oxidation of secondary alcohols is:

R₂-CHOH → R₂-CO + H₂O

(c) Resistance of tertiary alcohols to oxidation

Tertiary alcohols do not undergo oxidation reactions under typical conditions because they lack a hydrogen atom on the carbon attached to the hydroxyl group. Since oxidation reactions involve the removal of a hydrogen atom from the alcohol, tertiary alcohols are not oxidized to aldehydes or carboxylic acids.

no reaction

Below are some examples of Oxidation Reactions of primary alcohols
1.

2.

3. 

Question: A

Identify A

Ans.

Some Commercially Important Alcohols

Methanol and Ethanol

• Methanol (CH3OH) and ethanol (C2H5OH) are the simplest members of the primary alcohol family and have a wide range of applications in the fuel industry. Some important uses of methanol and ethanol are listed in this article.

1. Uses of Ethanol

• Owing to its antibacterial and antifungal properties, ethanol (also known as ethyl alcohol) is used in many hand sanitizers and medical wipes.
• Ethanol is also used as an antiseptic and as a disinfectant.
• In cases of ethylene glycol poisoning or methyl alcohol poisoning, ethanol is often administered as an antidote.

• Several medications that are insoluble in water are often dissolved in ethanol. For example, ethanol (in concentrations ranging from 1% to 25%) is used as a solvent for some analgesics and mouthwashes.
• Ethanol is the primary ingredient in many alcoholic drinks that are orally consumed for recreational purposes. It acts as a psychoactive drug by reducing anxiety and creating a feeling of euphoria in Humans. However, it also impairs cognitive and motor functions and acts as a central nervous system (CNS) depressant.
• Ethanol is used industrially in the production of ethyl esters, acetic acid, diethyl ether, and ethyl amines.
• This compound is widely used as a solvent due to its ability to dissolve both polar and nonpolar compounds.
• Since it has a melting point of -114.1^oC, ethanol is used as an ingredient in cooling baths in several laboratories. It also serves as the active fluid in many spirit thermometers.

2. Uses of Ethanol as a Fuel

• Ethanol is widely used as a fuel additive and as an engine fuel. Some forms of gasoline are known to contain up to 25% ethanol. 
• This compound has also been used as rocket fuel in some bipropellant rockets. When used in fuel, ethanol is believed to reduce carbon monoxide and nitrogen oxide emissions. 
• Since it is widely available and has low toxicity and cost, ethanol is used in direct-ethanol fuel cells (or DEFCs). However, commercially used fuel cells generally use methanol, hydrogen, or natural gas.

3. Uses of Methanol

• Methanol is widely used in the production of acetic acid and formaldehyde.
• In order to discourage the recreational consumption of ethanol, methanol is often added to it as a denaturant.
• This compound is also used as an antifreeze (an additive that is used to lower the freezing point of a liquid) in many pipelines.
• It is also used in sewage treatment plants since it serves as a carbon-based food source for denitrifying bacteria.
• The polyacrylamide gel electrophoresis (PAGE) technique involves the use of methanol as a destaining agent.
• A mixture of water and methanol is used in high-performance engines in order to increase power.
• Methanol is used in the production of hydrocarbons, olefins, and some aromatic compounds.
• It is also used in the production of methyl esters and methylamines.

• Methanol can be used as a fuel in several internal combustion engines. The chemical equation for the burning of methanol is given by:
• 2CH₃OH + 3O₂ → 4H₂O + 2CO₂
• However, the primary disadvantage of methanol as a fuel is that it has a tendency to corrode aluminum and some other metals.
• Another shortcoming of methanol as a fuel is that its energy density is approximately half of the energy density offered by gasoline. An advantage of methanol as a fuel is that it is relatively easy to store.
• The storage of liquid methanol is much easier than the storage of hydrogen gas or natural gas. Other merits of this compound include its biodegradability and its short half-life in groundwater.