CH₃OH — Methanol

Methanol (CH3OH), also known as methyl alcohol or wood alcohol, is the simplest alcohol in the organic chemistry family. It consists of a single carbon atom bonded to three hydrogens and a hydroxyl group (–OH). It is a clear, flammable liquid with a mild odor and is widely used in industrial processes. Historically, methanol was obtained through the destructive distillation of wood, hence its common name, but today it is produced synthetically from carbon monoxide and hydrogen gases.

Methanol is a crucial building block for producing chemicals like formaldehyde, acetic acid, and methyl tert-butyl ether (MTBE). It also serves as a fuel in race cars, marine engines, and in the production of biodiesel. However, due to its toxicity, methanol must be handled carefully since even small amounts can cause blindness or death if ingested.

The molecular structure of methanol can be represented as \(CH_3OH\). It consists of a methyl group (\(CH_3\)) attached to a hydroxyl group (\(OH\)). The carbon atom is sp³ hybridized and forms four single covalent bonds — three with hydrogen atoms and one with the oxygen atom of the hydroxyl group. The O–H bond is polar due to the high electronegativity of oxygen, giving methanol its polarity and hydrogen-bonding ability.

This polarity allows methanol to mix with water and many other polar solvents easily, making it an excellent solvent in laboratories and industries. Hydrogen bonding between methanol molecules significantly affects its boiling point and viscosity compared to non-polar organic compounds of similar molecular weight.

Industrial production of methanol is achieved primarily through the catalytic hydrogenation of carbon monoxide using a copper-based catalyst under high pressure and moderate temperature:

This process, known as the synthesis gas process or syngas method, involves a mixture of carbon monoxide and hydrogen derived from natural gas reforming. The reaction is exothermic and yields methanol of high purity after condensation and distillation.

Earlier, methanol was obtained by destructive distillation of wood — heating wood in the absence of air to produce gases and liquids that condense to yield crude methanol, tar, and acetic acid. However, this method is now obsolete due to low efficiency.

• Physical Nature: Methanol is a colorless, volatile liquid with a low boiling point of 64.7°C.
• Polarity: It is a polar solvent capable of forming hydrogen bonds, leading to high solubility in water.
• Combustion: Methanol burns with a pale blue, nearly invisible flame producing carbon dioxide and water.

Chemical Reactions:

• Oxidation: Methanol can be oxidized to formaldehyde (\(HCHO\)) and further to formic acid (\(HCOOH\)).
• Acid-Base Nature: The hydroxyl hydrogen can be replaced by metals like sodium to form alkoxides (sodium methoxide).
• Dehydration: When heated with concentrated sulfuric acid, methanol dehydrates to form dimethyl ether (\(CH_3OCH_3\)).

Methanol plays an essential role in various industries. Some of its key uses include:

1. Fuel: Used as a clean-burning fuel in racing cars and as an additive to gasoline to improve combustion efficiency.
2. Feedstock: Acts as a precursor for chemicals such as formaldehyde, acetic acid, and methyl tert-butyl ether (MTBE).
3. Biodiesel Production: Serves as a reactant in transesterification of fats and oils to produce biodiesel.
4. Antifreeze: Used in windshield washer fluids and as a coolant due to its low freezing point.
5. Solvent: A versatile solvent in paints, varnishes, and inks.

Because of its versatility and high energy density, methanol is also being explored as a potential hydrogen carrier and alternative energy source for fuel cells.

Methanol is highly toxic. Ingestion, inhalation, or prolonged skin exposure can lead to severe poisoning. Inside the body, methanol is metabolized into formaldehyde and formic acid, which can cause metabolic acidosis, blindness, and even death. Therefore, methanol should only be handled with proper safety equipment such as gloves, goggles, and ventilation.

Antidotes for methanol poisoning include ethanol or fomepizole, which inhibit alcohol dehydrogenase — the enzyme responsible for converting methanol to its toxic metabolites.

Methanol is biodegradable and less persistent in the environment compared to petroleum fuels. However, accidental spills can contaminate soil and water, posing toxicity risks to aquatic life. Its use as a renewable fuel derived from biomass or carbon dioxide conversion offers a sustainable pathway to reduce greenhouse gas emissions.

• Methanol was first isolated in the 17th century by distilling wood, hence the name wood alcohol.
• It burns with an almost invisible flame, making it hazardous in open environments.
• Methanol is used in producing formaldehyde, one of the most widely used industrial chemicals.
• It is used as a rocket fuel component and in fuel cells for clean energy applications.