15 points on general characteristics of organic compounds

1.The nature of the covalent bonding in organic compounds can be described in terms
of orbitals hybridization concept, according to which carbon can have sp 3, sp2 and
sp hybridized orbitals. The sp3, sp2 and sp hybridized carbons are found in
2.ucatcompounds like methane, ethene and ethyne respectively.
The chemical properties of an element depend on the electronic configuration of the
outer shell.
3.Hydrogen bond a particularly strong intermolecular attraction between a non-
bonding pair of electrons and an electrophilic O—H or N—H hydrogen. Hydrogen
bonds have bond energies of about 5 kcal/mol (21 kJ/mol), compared with about
100 kcal/mol (about 400 kJ/mol) for typical C—H bonds.
4.This mixing and redistributoin of energy is called hybridisation and the resultant
Organic reaction mechanism concepts are based on the structure of the substrate
5.orbitals are called hybrid orbitals.
molecule, fission of a covalent bond, the attacking reagents, the electron
displacement effects and the conditions of the reaction.
6.The hydrogen bond is an electrostatic attractive force between covalently bonded
hydrogen atom of one molecule and an electronegative atom (such as F, O, and N)
of another molecule.
7.A covalent bond may be cleaved in heterolytic or homolytic fashion. A heterolytic
cleavage yields carbocations or carbanions, while a homolytic cleavage gives free
radicals as reactive intermediate.
8.Reactions proceeding through heterolytic cleavage involve the complimentary pairs
of reactive species. These are electron pair donor known as nucleophile and an
electron pair acceptor known as electrophile.
9.Organic compounds can also be classified on the basis of functional groups, into
families or homologous series.
10. Organic chemistry deals with millions of compounds. In order to clearly identify
them, a systematic method of naming has been developed and is known as the
IUPAC (International Union of Pure and Applied Chemistry) system of
nomenclature.
11. Inductive effect is donation or withdrawal of electron density through sigma bonds.
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12. A molecule or ion can be expressed in two or more valid lewis structures can be
drawn, differing only in the placement of valence electrons. These lewis structures
are called resonance forms. Individual resonance forms do not exist, but we can
estimate their relative energies. The more important (lower –energy) structures are
called major contributors, and the less important (higher-energy) structures are
called minor contributors. When a charge is spread over two or more atoms by
resonance, it is said to be delocalized, and the molecule is said to be resonance
stabilized.
13. Electromeric effect is defined as the complete transfer of a shared pair of
 -electrons to one of the atoms joined by a multiple bond on the demand of an
attacking reagent.
14. Compounds containing carbon and hydrogen only are called hydrocarbons. A
hydrocarbon is termed saturated if it contains only carbon-carbon single bonds.
15. Hyperconjugation involves delocalization of s electrons of C – H bond of an alkyl
group directly attached to an atom of unsaturated system or to an atom with an
unshared p orbital. The s-electrons of C – H bond of the alkyl group enter into
partial conjugation with the attached unsaturated system or with the unshared p
orbital. Hyper conjugation is a permanent effect.
16. Unsaturated hydrocarbons are those, which contain at least one carbon-carbon
double or triple bond.

17. The inductive, resonance, electromeric and hyperconjugation effects may help in
the polarization of bond making certain carbon atom or other atom positions as
places of low or high electron densities.
18. Organic reactions can be broadly classified into following types: substitution,
addition elimination and rearrangement reactions.
19. The order of decreasing priority for some functional groups is:
—SO3H, —COOH, —COOR (R = alkyl group), —COCl, —CONH2, —CN,
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—HC = O, >C = O, —OH, —NH2, >C=C
20. Reactive intermediate is a short-lived species that is never present in high
concentration because it reacts as quickly as it is formed.
21. Isomers are different compounds with the same molecular formula.
22. Isomers are grouped into two broad classes: constitutional isomers and
stereoisomers. Constitutional isomers (structural isomers) differ in their bonding
sequence; their atoms are connected differently. Stereoisomers have the same
bonding sequence, but they differ in the orientation of their atoms in space.
Stereochmeistry is the study of the structure and chemistry of stereoisomers.
23. Electrophilic reeagent can be of two types, namely
(ii) Neutral electrophiles.
(i) Positive electrophiles and
24. Negative Nucleophiles: Species which carry an excess of electron pair and are
negatively charged.
25. Alkanes show conformational isomersm due to free rotation along the C – C sigma
bonds. Out of staggered and the eclipsed conformations of ethane, staggered
conformation is more stable as hydrogen atoms are farthest apart. Alkenes exhibit
geometrical (cis-trans) isomersm due to restricted rotation around the carbon-carbon
double bond.