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ORGANIC CHEMISTRY

Organic chemistry deals with carbon and its compounds with the exception of oxides of carbon.

Hydrocarbons: These are compounds of carbon and hydrogen only.Eg. CH4

Sources of hydrocarbons: They can be obtained from coal (solid), petroleum (liquid) and natural gas (gas).

Classification of hydrocarbons:

Hydrocarbon

Aliphatic Aromatic Acyclic																										Cyclic Branch chain															Cycloalkane Straight chain H										H H		H	H					H			H	H								C						C H H H		C			C			C		H	H		C					C				C			H H		H	H					H									H												C H H Propane											H					C			H																					Benzene Cyclopropane H 2-Methylpropane

TYPES OF HYDROCARBONS:

i.Saturated hydrocarbons: These are hydrocarbons that their carbons atoms are joined by a single covalent bond.E.g. Alkanes. Such as methane, ethane, propane, butane etc.

H	H		H		H	H	H		H H		C		C		C		H	H	C	C		C		C		H H	H		H		H		H		H		H

Propane	Butane

ii.Unsaturated hydrocarbon: These are hydrocarbons that their carbons atoms are joined by a double bond (alkenes) or triple covalent bond (alkynes).

Example of alkenes:

H H	H	H C					C					C				C					C		H H H								H H				H Ethene Prop-1-ene or propene Examples of alkynes: H H H		C						C			H							H		C				C			C		H H																		H

ALKYL GROUP: This is a group derive from alkane by losing one hydrogen atom. It has a general molecular formula CnH2n +1 and is denoted by ‘R’.

Example:

Alkane	Formula	Alkyl	Formula Methane	CH4	Methyl	CH3 Ethane	C2H6	Ethyl	C2H5 Propane	C3H8	Propyl	C3H7 Butane	C4H10	Butyl	C4H9

HOMOLOGOUS SERIES: This is a family of organic compounds with similar chemical properties due to the presence of the same functional group.

Characteristics of homologous series:

i.They possess similar structures and chemical properties. ii.They differ in formula by –CH2 group and 14-atomic mass unit.

iii.They possess similar names in their suffixes (ending words).

iv.They have the same general molecular formula.

Example

S/N	Homologous series	General molecular formula 1	Alkanes	CnH2n +2 2	Alkenes	CnH2n 3	Alkynes	CnH2n	-2 4	Alkanols	CnH2n	+ OH 5	Alkanoic acids	CnH2n	+1 COOH

Examples of homologous series: Alkanes, alkenes, alkynes, alkanols (alcohols), alkanoic acids (carboxylic acids) alkanal (aldehydes), alkanone (ketones), alkanoate (esters), alkoxy (ethers), amides, amines, haloalkanes.

Each member of the series has a family with the same functional group eg.

S/N	Alkanes	Formula	Alkenes	Formula	Alkynes	Formula 1	Methane	CH4	-	-	-	- 2	ethane	C2H6	ethene	C2H4	ethyne	C2H2 3	propane	C3H8	propene	C3H6	propyne	C3H4 4	butane	C4H10	butene	C4H8	butyne	C4H6 5	pentane	C5H12	pentene	C5H10	pentyne	C5H8 6	hexane	C6H14	hexene	C6H12	hexyne	C6H10 7	heptane	C7H16	heptene	C7H14 8	octane	C8H18 9	nonane	C9H20 10	decane	C10H22

FUNCTIONAL GROUP: This is an atom, group of atoms or a bond common to homologous series and with similar chemical properties.

S/N		Functional group											Homologous series	Example 1																																							alkanes	ethane 2																																							alkenes	ethene 3																																							alkynes	ethyne 4											OH																			alkanol (alcohol)	ethanol 5							COOH or					C			O						akanoic acid (carboxylic	ethanoic acid																OH																																										acid) 6							CHO or			C							O				alkanal (aldehydes)	ethanal H 7																		O																				alkanone (ketones)	propanone C R’ 8																			O																			alkanoate (esters )	etheylethanoate C O					R’

9		Alkoxy (ethers)	ethoxy ethane O	R’ 10	O	amides	ethanamide C		NH2 11		amines	ethylamine NH2 12		Haloalkanes	Chloroethane X		X = halogen-Cl	bromoethane -Br

ISOMERISM: It is the existence of two or more compounds with the same molecular formula but different structural formula. These different structures are called isomers.

Types of isomerism:

i.Structural isomerism

ii.Geometrical isomerism

iii.Optical isomerism.

Examples: Butane has two isomers while pentane has three isomers.

Examples of isomers of butane (C4H10)

H	H	H	H													H	H				H H		C	C		C		C		H						H		C			C		C		H H	H	H	H												H						H butane or n-butane												H								H C Iso-butane or 2-methyl propane Examples of isomers of pentane (C5H12):								H H	H	H		H	H								H	H				H  H H		C			C		C		C			C	H						H		C			C		C			C		H H	H	H	H  H	H			H							H n-pentane or pentane			H C			H			H			C				H Iso-pentane or 2-methylbutane H					H								H

H	C	C	C	H

H	H

H	C	H		2, 2-dimethylpropane Examples of isomers of ethanol and	H	methane with a molecular formula C2H6O H	H					H		H H			C		C		O		H		H		C		O		C		H H	H					H		H ethanol (alkanol family)			Methoxymethane (alkoxy family) Examples of geometric isomerism: Cl						Cl		Cl						H C						C					C							C H					H		H						Cl Cis-1, 2- dichloethene				Trans-1, 2- dichloroethene

NAMING OF ORGANIC COMPOUNDS USING IUPAC NOMENCLATURE: Rules for naming organic compounds:

i.Consider the longest carbon chain and count the number of carbon to represent the name of the compound, while shorterchain represents the substituent.E.g.

H	H	H	H	H	H  H HC   3C   4C   5C	6C   7C	8C   H H H 2C H H	H	H	H	H H	1C	H		3-methyloctane

H

ii.Number the carbon atoms from the end or position which is closer to functional group, and for single bonding, the numbering starts from the branch chain position. E.g.	H		H	H			H H		4C		3C				2C				1C		H H H	C		H						3-methylbut-1-ene

H