Organic Compounds with Functional Group Containing Oxygen Part – 1
→ Alcohols are the compounds that have one or more hydroxyl (— OH) group bonded to carbon atom of aliphatic hydrocarbons while phenols are the compounds which have one or more hydroxyl (— OH) group bonded to the carbon atom of aryl nature or aromatic rings.
→ Hydroxyl group containing organic compounds obtained by replacing one hydrogen atom from aliphatic hydrocarbons by hydroxyl group are alcohols whereas those obtained by replacing hydrogen atom of aromatic hydrocarbons are phenols.
→ In other words, hydroxyl derivatives of hydrocarbons (aliphatic or aromatic) are known as alcohols and phenols.
→ Ethers are also organic compounds of oxygen containing functional group. These are also known as functional isomers of monohýdric alcohols.
→ The substitution of hydrogen atom in a hydrocarbon by an alkoxy (RO) or aryloxy group (ArO) gives ethers.
Organic Compounds with Functional Group Containing Oxygen of Alcohols
Hydroxy derivatives of alkanes are known as alcohols. These compounds are obtained by replacing one or more hydrogen atoms from alkane molecule by hydroxyl group (—OH).
Organic Compounds with Functional Group Containing Oxygen of Phenols
Phenols are hydroxyl derivatives of aroffiatic hydrocarbons in which hydroxyl group is directly attached to benzene ring. They are also known as carbolic acids. It was first isolated in the early nineteenth century from coaltar.
Organic Compounds with Functional Group Containing Oxygen of Ethers
→ Those organic compounds in which both the valency of bivalent oxygen atom are satisfied by alkyl groups are called ethers or alkoxy alkane. Aryl groups can also be present in place of alkyl groups.
→ Their general formula is R—O—R’. Where R and R’ = alkyl/aryl group, R and R’ are same in an ether then it is called simple ether. On the other hand if R and R’ are different in the formula of ether, then it is called mixed ether. For example,
→ Ether can be considered as derivative of water if in place of two hydrogen atoms alkyl groups are placed. Ethers are also called anhydrides of alcohol. On elmination of one molecule of water from two molecules of alcohol, ether is obtained.
→ Their general formula is CnH2n+2O.
→ Where value of n is always greater than one.
Summary of the chapter and glossary
Hydroxy derivatwet ot alkanes are known as alcohols.
Akohols can be prepared by the following methods:
- By alkene.
- By Grignard reagent.
- By reduction of carboxyhc acid and eater.
- By haloalkane.
- By hydrolysis of ester.
- By aliphatic primary amine.
→ Due to mtcrmvlt’cular hydrogen bonding, skohols with low molecular weight are soluble in water and as the molecular weight increases solubility decreases.
Chemical reactions ofalcohols can be divided into four parts:
- Due to the cleavage of O—H bond of hydroxyl group.
- Due to the cleavage of C—O bond of alkanol.
- Reactions involving alkyl and hydroxy) group.
- Duc to the presence of lone pair of electrons on oxygen atom of hydroxyl group.
→ Aromatic hydroxy compounds in which hydroxy group is directly attached to benzene ring are known as phenols.
→ Phenol is colourless liquid with characteristic smell. When it come in contact with air it geta oxidised and form para.benzoquinone due to which it changes to pink colour, it is sparingly soluble in water.
Chemical reactions of phenol are divided into three classes :
- Of phenolic group
- Of benzene ring
- Condensation Reactons
→ Ether are colourless liquids with pleasant smell. They are less soluble in water.
→ Estrification : Thc’ reaction of alcohol and carboxylic acid in the presence of conc. H2SO4 to form esters.
→ Hydrogenolysis : Catalytic hydrogenation is called hydrogenolysia.
Friedel Craft alkylatlon
Reimer Tiemann Reaction
R’—O—Na + X—R → R’—O—R + NaX