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Alcohol

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Introduction to Alcohols

Alcohols are organic compounds characterized by one or more groups of hydroxyl (-OH) bound to an alkyl group carbon atom (hydrocarbon chain). Alcohols can be known as organic water derivatives (H2O) in which an alkyl group, usually represented by R in organic structures, has substituted one of the hydrogen atoms. Here, we will study alcohol structure, what is the chemical formula of alcohol, and the application of alcohol in detail.


Alcohol Structure and Alcohol Molecular Formula

Alcohol can be described as having an sp3 hybridized tetrahedral oxygen atom with nonbonding electron pairs occupying two of the four sp3 hybrid orbitals, similar to water.  Alkyl groups are usually bulkier than hydrogen atoms, however, so the R-O-H bond angle in alcohols is generally greater than the water bond angle of 104.5 ° H-O-H. The 108.9 ° bond angle in methanol, indicates the influence of the methyl group, which is larger than water's hydrogen atom.


Classification of Alcohols 

As we studied what are alcohols, how are they classified is given in the section below-

Alcohols are classified on the basis of the carbon atom to which the hydroxyl group is attached.

  1. Primary Alcohols - if a hydroxyl group is attached to a carbon which is further bonded to another carbon atom.

  2. Secondary Alcohols - if a hydroxyl group is attached to a carbon atom which is further attached to the other two carbon atoms.

  3. Tertiary Alcohols- if a hydroxyl group is attached to a carbon atom which is further attached to the other three carbon atoms.


Physical Properties

  1. Boiling Point

In contrast to other hydrocarbons with similar molecular masses, alcohols typically have higher boiling points. We may relate this to the presence of intermolecular hydrogen bonding of alcohol molecules between hydroxyl groups. In addition, the boiling point of alcohols in the aliphatic carbon chain increases with an increase in the number of carbon atoms.

  1. Solubility of Alcohols

The solubility of alcohol in water is determined by the hydroxyl group. In the formation of intermolecular hydrogen bonding, the hydroxyl group in alcohol takes part. Thus, hydrogen bonds between molecules of water and alcohol make water-soluble in alcohol. With the rise in the size of the alkyl group, the solubility of alcohol decreases because of the hydrophobic nature of the alkyl group.

  1. Acidity of Alcohols

Alcohols react and form the corresponding alkoxide with active metals such as sodium, potassium, etc. Such alcohol reactions are representative of their acidic character. The acidic nature of alcohol is due to the OH bond polarity. Alcohol acidity decreases when the hydroxyl group is attached to an electron-donating group. This is because it raises the oxygen atom's electron density. Thus, primary alcohols are more acidic in general.


Chemical Reactions of Alcohols

  1. Sodium ethoxide and hydrogen gas are created when ethanol reacts with sodium metal (a base).

2ROH + Na→2RO+Na-+ H2

  1. Formation of Halides

Halogens such as chlorine or bromine replace the alcohol with the -OH group.

ROH+ Zn+HCl → R-Cl

R2C-OH + HCl→ R2CCl

  1. Reaction with HNO3

There is oxidation, followed in this reaction by gas evolution.

R-OH + HO-NO2→ R-O-NO2

  1. Reaction with Carboxylic Acid (Esterification)

Carboxylic acid reaction with alcohol and an acid catalyst leads to the formation of the ester (along with water). This is Fischer esterification.

R-OH +R’-COOH +H+↔ R’-COOR

  1. Dehydration of Alcohol

Alcohols in an acidic solution dehydrate. Intra-molecular dehydration, according to the Satyzeff Law, contributes to alkene formation, whereas ether is formed by intermolecular dehydration

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Application of Alcohol

Some Examples of Alcohol-

  1. Methanol

  • As a polar organic solvent, methanol has excellent properties. 

  • It is widely used as an industrial solvent. 

  • Methanol has a high octane level and has low pollutant emissions. For many cars, this makes it perfect.

  1. Ethanol

With a high octane level and low emissions, ethanol is outstanding motor fuel. However, in peculiar systems that resist the propensity of alcohol to dissolve plastic pieces, we may use it as a fuel. Without any changes, we can use solutions of 10 percent ethanol in gasoline (gasohol) in most vehicles. Ethanol fuels are usually produced today from natural materials, such as maize or sugar.

  1. Ethylene Glycol

As an automotive antifreeze and as an element in hydraulic fluids, printing inks, and paint solvents, we use ethylene glycol commonly. In manufacturing polyesters, explosives, alkyd resins, and synthetic waxes, we also use them as a reagent.


Did You Know?

Alcohols are acids that are weak. The most acidic simple alcohols are almost as acidic as water (methanol and ethanol), and the other alcohols are much less acidic. 

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To generate an alkoxide ion (R-O-), a strong base will deprotonate alcohol. The hydrogen atom of an alcohol, for instance, is abstracted by sodamide (NaNH2), a very strong base. By reducing the proton to hydrogen gas, metallic sodium (Na) or potassium (K) is also used to form an alkoxide. 

Alcohol can be deprotonated by a solid base to yield an alkoxide ion. The hydrogen atom in alcohol is abstracted by sodamide. By reducing the proton to hydrogen gas, metallic sodium or potassium is also used to form an alkoxide. The most popular synthesis of ethers, for example, involves the attack on an alkyl halide by an alkoxide ion known as   Williamson ether synthesis


FAQs on Alcohol

1. Is ethyl alcohol poisonous in hand sanitizer?

Usable alcohols are just ethyl alcohol and isopropyl alcohol (also known as 2-propanol) in hand sanitizer. Other forms of alcohol are not suitable in hand sanitizers, like methanol and 1-propanol, since they can be harmful to humans.

2. What is the difference between alcohol and ethanol?

Alcohols are organic molecules that are composed of atoms of carbon (C), oxygen (O), and hydrogen (H). The alcohol is called ethanol if two carbons are present (also known as ethyl alcohol). The form of alcohol found in drinks like beer, wine, and liquor is ethanol. The alcohol used in alcoholic drinks is ethanol.

3. Is alcohol acid or alkaline?

By the Arrhenius concept of acid and base, when dissolved in water, alcohol is neither acidic nor basic, as it neither produces H+ nor OH- in the solution. Generally, they are poor acids. Brønsted acids with pKa values normally in the range of 15-20 are very weak alcohols.