Explanation
Structures (a) & (b) are stable as octet of all atoms is complete. In structure (d) the electron deficient of positive charged carbon is duly compensated by one pair electrons of adjacent oxygen atoms while such neighbour group support is not available in structure (c). So, (c) is least stable than (d)
Correct order is 4 < 2 < 3 < 1 presence of phenyl group, makes (1), (2), (3) are more stable than (4). Presence of phenyl group increases stability of carbocation through delocalisation of electrons. So (1) and (3) are more stable than (2). Presence of –Ome group ie +I effect, carbocation (2) is more stable than (1)
Order of stability of carbocation Benzyl > Allyl > Propyl. Benzyl is more resonance stabilised. Allyl is less resonance stabilised. Propyl is stabilised by +I effect of CH2CH3 group
More the number of resonating structures more will be the stability. So most stable carbonium ion is (C6H5)3 C+
Increasing order of stability of carbocation 10 carbocation < 20 carbocation < 30 carbocation
On halogenation Cis-alkene produces racemic mixture
In (a), 1,3 butadiene, conformational change is possible between C2-C3 bond in which atoms will be present in more than single plane. While (b) and (c) are present in single plane. In (a) alkene, the terminals H–C–H planes are perpendicular to one another.
I has one chiral carbon. So, it has two enantiomers. Also in II, it has two chiral carbons but having no symmetry. So, it has four isomers. In, II and IV, there is no chiral carbon that means it has no stereoisomers
Option (b) exhibts optical isomerism as the central carbon is attached to four different substituents, hence it is chiral, therefore optically active.
The priority of groups is decided by the following rules
(a) Atoms having higher atomic number gets higher priority
(b) It priority is not decided by first rule then the next atoms are considered for priority assignment.
(c) Where there is a = bond or = bond both atoms are considered to be duplicated or-triplicated. So, correct order pf priority of groups in D-glyceraldehyde is as
OH(1),CHO (2) , CH2OH (3) and H (4)
According to cahn-ingold-prelog sequence rules, when the atom of a group has higher atomic number then the group gets higher priority.
Order of priority of groups is –OH > – COOH > – CHO > – CH2OH
No. of optical iosmers = 2n = 21 = 2
Total number of geometrical iosmers = 6
I and II are chiral compounds because all four atoms attached to carbon are different
Metamers of ethy propionate are CH3COOC3H7 , C3H7COO CH3
Compound has two geometrical isomers and two optical isomers
A compound could be optically active only when it contains atleast one chiral centre
Carboxylic acid and esters show functional group isomerism C2H5COOH and CH3COO CH3 are two functional group isomerism
A carbon atom which is attached by four different group is called an asymmetric carbon atom or chiral centre.
The enol content in any keto-enol will be maximum when enol form is stabilised by hydrogen bonding. In acetyl acetone, enol form is stabilised by H-bonding, hence it has more enol content than other
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