Nomenclature and Preparation Flashcards
(22 cards)
How are ethers named
Prefix(smaller chain)+oxy+suffix(bigger chain_
Bond angle in alcohols
slightly less than 109°28’
Why is the bond length in phenols less than that in methanol?
due to
-partial double bond character by the conjugation of the unshared electron pair of oxygen with the aromatic ring.
-sp2 carbon through which oxygen is attached.
Bond angle in Ethers
More than angle in tetrahedral structure due to repulsive interaction between the two R groups.
Bond length in ethers
almost the same(141pm) as that of alcohols
Preparation of Alcohols by alkenes
Addition of water in the presence of acid.
Mechanism of preparation of alcohol by alkene
-Protonation to form a carbocation ny electrophilic attack of H3O
-Nucleophilic attack of h2o on carbocation
-Deprotonation to form an alcohol
Hydroboration-oxidation
Addition of diborane
addition of same alkene 2 more times to produce trialkyl boranes.
oxidised by hydrogen peroxide(h2o2) to alcohols
reduction of aldehydes and ketones
catalyst-plantinum.palladium, nickel
or NaBH4 or LiAlH4.
Reduction of carboxylic acid through LiAlH4
reduced to primary alcohols using catalyst LiAlH4
Reduction of carboxylic acid(Commercial method)
reduced first to esters and then to alcohols by hydrogen + catalyst.
From Grignard reagants
reacts worth R-Mg-X to form an adduct on hydrolysis forms alcohol
Other name for phenol
Carbolic acid
Preparation from haloarenes(phenol)
chlorobenzene+naoh at 623K and 300 atm to form sodium phenoxide which acidifies to phenol
From benzenesulphonic acid
Benzene+oleum then heated (forms benzene with so3h compound) with naoh to form sodium phenoxide which is acidified to phenol.
From diazonium salts
Aniline(nh2 on benzene) + nano2 +hcl tp give n2cl on benzene which reacts with warm water to form phenol
Cumene
isopropylbenzene
From cumene
Cumene is oxidised to form cumene hydroperoxide which reacts with acid to form phenol and acetone(propanone)
Properties of alcohols and phenols are due to which group and are modified by which group
due to hydroxyl group and modified by alkyl and aryl groups.
Boiling points
Increases with increase in carbon atoms(more vanderwaals force) but decreased with increase in branching as it the van der waals force decrease due to lesser surface area.
Why do alcohols have high boiling points?
due to intermolecular hydrogen bonding which is absent in ethers and hydrocarbons.
Solubility
decreases with increase in size of alkyl/aryl group as they are hydrophobic.
