Organic Chemistry

Introduction of Alcohol

A large class of alcohols and organic compounds is a compound in which a hydrogen atom in an aliphatic hydrocarbon, an alicyclic hydrocarbon or an aromatic hydrocarbon side chain is substituted with a hydroxyl group.

Alcohol commonly referred to is a hydroxyl group with a saturated, SP3 hybrid of carbon atoms linked. If the hydroxyl group is bonded to the benzene ring, it is a phenol; if the hydroxyl group is linked to the sp2 hybridized olefinic carbon, it is an enol.

The properties of phenols and enols are quite different from those of general alcohols.

Physical properties

Alcohol compounds are affected by hydroxyl groups, there are hydrogen bonds between molecules, and there are hydrogen bonds between alcohol molecules and water molecules in water.

Therefore, their physical properties are quite different from the corresponding hydrocarbons. Mainly in the melting point is relatively high, there is a certain solubility in water. Introduction of Alcohol

In general, lower alcohols have better water solubility, and methanol, ethanol, and propanol can be miscible with water in any ratio. The alcohol of 4 to 11 carbon atoms is an oily liquid, partially soluble in water.

Later, as the number of carbon atoms increases, the influence of the hydrocarbon group on the molecule becomes larger and larger, so that the physical properties of the higher alcohol are closer to the corresponding hydrocarbon. In addition, lower alcohols have a special odor and a spicy taste, while higher alcohols are odorless and tasteless.

The physical properties of some alcohols are shown below.


The lower alcohol has a melting point and a boiling point much higher than the melting point and boiling point of the hydrocarbon having the same number of carbon atoms, which is a result of hydrogen bonding between the alcohol molecules. Introduction of Alcohol

The experimental results show that the hydrogen bond break requires about 21 to 30 KJ/mo1, which indicates that it is much weaker than the atom (105 to 418 KJ/mol).

When the alcohol is in the solid state, the association is relatively strong; in the liquid state, the hydrogen bond is broken and then formed again; but in the dilute solution of the gas phase or the non-polar solvent, the alcohol molecules are far apart from each other, and the individual alcohol molecules can exist separately.

How Alcohol is Made

There are more than two positions in the polyol molecule to form a hydrogen bond, and thus the boiling point is higher, such as the boiling point of ethylene glycol at 197 ° C. Hydrogen bonds between molecules increase with increasing concentration, and intramolecular hydrogen bonds are not affected by concentration.

The structure of the alcohol is illustrated by taking methanol as an example. In the methanol molecule, the bond length of the carbon-oxygen bond is 143 pm, and the bond angle of the ∠COH bond is 108.9°.

It is generally considered that the oxygen atom in the alcoholic hydroxyl group is sp3 unequal hybridization, and the six electrons of the outermost layer of the oxygen atom are distributed in 4 On the sp3 hybrid orbitals, two sp3 orbitals containing single electrons form carbon-oxygen bonds with carbon atoms and hydrogen atoms, respectively, and the remaining two pairs of unshared electrons occupy the other two sp3 orbitals.

The two pairs of unshared electrons on the hydrogen-oxygen bond and the oxygen form a cross-dominant conformation with the three carbon-hydrogen bonds of the methyl group. The bond length of methanol, the bond angle, and the ball and stick model of methanol and ethanol are shown below.

Alcohol with Lowest Calories

Since the electronegativity of carbon and oxygen are different, the carbon-oxygen bond is a polar bond and the alcohol is a polar molecule. In general, the dipole moment of alcohol is 5.7*10^-30Cm. However, when a hydroxyl group is bonded to a double bond or a triple bond carbon, the sp3 hybrid orbital of oxygen forms a sigma bond with the sp hybridization orbital of carbon.

Under normal conditions, the two largest groups on two adjacent carbon atoms are most stable for the cross-conformation and are the dominant conformations, but when the two groups may be hydrogen-bonded, the formation of hydrogen bonds can be increased. Introduction of Alcohol

The stability of the molecule (the bond energy of the hydrogen bond is about 21 to 30 KJ/mol). The two groups are in the ortho-cross conformation to become the dominant conformation.

Organic Alcohol Structure Inference Method

Experiments show that the structure of organic alcohol compounds has a good correlation with its chromatographic retention index. When predicting or predicting alcohol, first calculate the topological index of its structure, and then calculate its chromatographic retention by regression equation according to the topological index value. Index I, and then qualitative analysis under the same conditions of chromatography.

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At the same time, the structural formula can be inferred based on the chromatographic retention index.

Type of Alcohol

Methanol (wood alcohol), the preparation of methanol is synthesized with synthesis gas (CO and H2) in the presence of heat, pressure, and catalyst.

Ethanol, commonly known as alcohol, is the most widely used class of alcohol.

Ethylene glycol, the simplest and most important glycol, is a viscous, colorless liquid with a sweet taste.

Glycerol, commonly known as glycerin, is a colorless, sweet, viscous liquid that mixes with water is insoluble in organic solvents, and has strong water absorption.


सबसे पहले हम देखेंगे की Alcohol होते क्या है? Alcohol वो Compound होते है जिनमे OH function होते है



Classification of alcohol:-

  1. Number of OH group

R – OH

अगर किसी compound में एक OH group है तो उसे Monohydric कहते है! और अगर दो group है तो उसे dihydric कहेगे! इसी प्रकार अगर किसी compound  में 3 OH group है, तो उसे trihydric कहेगे! और इसी compound को Glycerol कहते है!


किसी compound में 3 से अधिक OH group है, तो उसे Polyhydric कहेगे!

Glucose, इसका एक example है!

Type of Alcohol:-

Types of alcohol are defending on the following steps.

Preparation of alcohol:-


Alkene से दो तरह का Alcohol बनता है! पहला H2O के साथ C Acid की reaction से बनता है, दूसरा H2O के साथ B2H6, H2O2 NaOH की reaction से बनता है! यहाँ दोनो reaction से अलग अलग तरह का Alcohol बनेगा! C. Acid (H+) से बना Alcohol, Secondary alcohol होगा! Introduction of Alcohol

और यहाँ reaction Markovnikov के according to होगी जबकि दूसरी reaction anti-Markovnikov होगी!

निचे दिए example को देखिये:-

  1. Carbonyl Compound:-

जिन compound में carbon group होता है, वह Carbonyl compound में आते है!

Aldehyde, ketone, carboxylic Acid Ester.

जब इन compound से carbonyl group को reduce करते है, तो alcohol मिलता है!

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Aldehyde केवल primary Alcohol बनाते है!

But Ketone Secondary Alcohol देते है!

  1. Grignard Reagent (pronounced /ɡriɲar/)

R – MgX

इसमें निम्नलिखित reaction का example लेते है:-

जब कोई Grignard reagent किसी carboxyl group से reaction करेगा,

तो यह primary, secondary और treasury alcohol देगा और यह depend करता है की Grignard  Reagent किस carboxyl group से reaction कर रहा है!

Read also:-

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  2. What are the Metals?
  3. physical metallurgy of metals
  4. Natural sciences disappear in India
  5. Exciting and entertaining chemical tricks

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