introduction and naming organic compounds.ppt

alkanes class 10th presenttaion.

1. Naming Alkanes

2. What is organic chemistry?
•study of carbon, the compounds it makes,
and the reactions it undergoes
•over 16 million carbon-containing compounds
are known
•because the C-C single bond (348 kJ mol
-1
) and
the C-H bond (412 kJ mol
-1
) are strong, carbon
compounds are stable
•carbon can form chains and rings

3. Organic Chemistry

4. Hydrocarbons
•Hydrocarbons - Organic compounds that contain
only carbon & hydrogen
–alkanes - contain only single covalent bonds
–alkenes - contain one or more carbon - carbon double bond
–alkynes - contain one or more carbon-carbon triple bond

5. Saturated vs. Unsaturated Hydrocarbons
Saturated hydrocarbons – contain
only single carbon-carbon bonds
alkanes
Unsaturated hydrocarbons – contain
double or triple carbon-carbon bonds
alkenes and alkynes
Carbon is “saturated”
with bonds

6. Representing Organic Compounds
Four ways of representing the same molecule:
a) molecular formula b) structural formula
c) condensed structural formula
CH
3
CH
2
CH
3
d) skeletal formula
each end and corner represents a carbon
each carbon is assumed to form four bonds
carbons are bonded to hydrogens (not shown), unless otherwise indicated
atoms other than carbons and hydrogens are represented by their symbols
C
3H
8

7. •empirical formula
–simplest ratio of
atoms in a
molecule
•molecular formula
–actual numbers of
atoms in a
molecule
Empirical Empirical
FormulaFormula
MoleculaMolecula
r Formular Formula
CHCH
44 CHCH
44
CHCH
33 CC
22HH
66
CHCH
22OO CC
66HH
1212OO
66
CHCH
22 CC
44HH
88
CHCH
22 CC
88HH
1616

8. structural formula
•unambiguously shows how the atoms are
bonded together
•can use condensed structural formulas
–bonds are omitted, repeated groups put
together, side chains put in brackets
•CH
3
CH
2
CH
2
CH
2
CH
2
CH
3

–or even CH
3(CH
2)
4CH
3
•CH
3CH(CH
3)CH
3

9. Alkanes
•General formula:
C
nH
(2n+2)
Nomenclature
•root prefix based on # of
carbons
•ending: -ane
Root prefixes# of carbon
atoms
Meth- 1
Eth- 2
Prop- 3
But- 4
Pent- 5
Hex- 6
Hept- 7
Oct- 8
Non- 9
Dec- 10

10. condensed

11. Straight-Chain vs. Branched Hydrocarbons
Straight chain:
Carbons are arranged in
one long chain
Branched:
Some carbons branch off
from a main
carbon chain

12. •hydrocarbon chains where all the bonds between hydrocarbon chains where all the bonds between
carbons are SINGLE bondscarbons are SINGLE bonds
•C
nH
2n+2
•draw out and write the structural formulas for
the following:
–CH
4
–C
2H
6
–C
3H
8
–C
4H
10
–C
5H
12
–C
6H
14
Names and Structural formulas for the non-
cyclic alkanes up to C
6
Alkanes

13. You must memorize
the root prefixes!
Root prefix# of carbon
atoms
Meth- 1
Eth- 2
Prop- 3
But- 4
Pent- 5
Hex- 6
Hept- 7
Oct- 8
Non- 9
Dec- 10
First four prefixes
Meth-
Eth-
Prop-
But-
monkeys
eat
peeled
bananas
Naming of non-cyclic alkanes by (IUPAC) method:

14. 3.use the suffix “-ane” to indicate that the substance is
an alkane
4.number the carbons in the chain consecutively,
starting at the end closest to a substituent
(groups attached to the main chain/most busy
end)

15. 5.name and number the location of each
substituent
–the name of the substituent will be written before the main
chain and will end with “–yl” (or just memorize the below)
•CH
3 is methyl
•C
2
H
5
is ethyl
•C
3
H
7
is propyl
And with 2 or more side chains:
5.use prefixes di-, tri-, tetra-, to indicate when there
are multiple side chains of the same type
6.use commas to separate numbers and hyphens
to separate numbers or letters.
7.name the side chains in alphabetical order

16. Example: Name this compound and write its formula
Solution:
Name
•Only single bonds  Compound is an alkane
•Three carbons  Prefix prop-
Formula
•Count C’s and H’s  3 C’s & 8 H’s
This compound
is propane
This formula is C
3H
8

17. Example:
Name the compound C
2H
6, and draw its structure.

18. Branched Hydrocarbons:
Naming side chains
1.Identify the parent chain: The longest possible HC chain
2.Identify substituents (side chains or groups)
Common side chains include:
Alkyl groups (add –yl to prefix)
CH
3
- methyl
CH
3CH
2- ethyl
CH
3CH
2CH
2- propyl
(CH
3)
2CH- isopropyl
Halide groups
Br- (bromo)
Cl- (chloro)
F- (fluoro)
I- (iodo)

19. CH
3-CH
2-CH
2-CH
2-CH
2-CH-CH
2-CH
3
CH
3
The parent chain contains 8 carbons: It is octane
There is a –CH
3 group attached to the octane
chain: It is a methyl group

20. 3.Number the parent chain, and indicate the carbon to which the
substituent group is attached.
•start counting from the end of the parent chain that gives the lowest
possible numbers
CH
3
-CH
2
-CH
2
-CH
2
-CH
2
-CH-CH
2
-CH
3
CH
3
8 7 6 5 4 3 2 1
This compound is: 3-methyloctane
substituentparent

21. If the same side chain appears more than once:
indicate how many times it appears by using prefixes:
di = 2, tri=3, tetra=4
number all carbons on the parent chain where groups are attached
separated by commas
CH
3
-CH-CH-CH
2
-CH
2
-CH
2
-CH
2
-CH
3
CH
3
CH
3
This compound is: 2,3-dimethyloctane
1 2 3 4 5 6 7 8

22. If there are different groups attached:
•list them alphabetically in the name
CH
3 – CH
2 – CH
2 - CH
- CH
- CH
- CH
3
CH
3CH
2
CH
3
CH
2
CH
3
ethyl groups
(C3, C4)
methyl
group (C2)
7 6 5 4 3 2 1
This compound is: 3,4-diethyl-2-methylheptane

23. CH3
CH3
CH3
CH3
CH3
•parent chain: nine carbons
•two methyl groups
•one ethyl group
Practice: Name this molecule

24. Cl

25. ACTIVITY : Name these molecules
CH
3CH
2
CHCH
3
CH
2CH
2
CH
3
CH
3 CH
CH
CH
3
CH
CH
3
CH
2CH
2CH
3
CH
2CH
3
CH
3CH
2CHCHCHCH
2CHCH
3
CH
3
CH
2CH
3
CH
3 CH
3
A) B)
C)

26. Practice: Draw the structures below
A)3-ethyl-2-methylpentane
B)3-ethyl-1,5,5-trimethylcyclohexene

27. •How about C
5H
12? The isomers are:
Pentane 2-methyl-butane 2,2-dimethyl propane

28. Nomenclature PracticeNomenclature Practice
CH
3 CH
3
CH
3
CH
3
Cl
Name this compound
Step #1: For a branched hydrocarbon, the longest
continuous chain of carbon atoms gives the root name
for the hydrocarbon
1
5
2 43
9
6
8
7
9 carbons = nonane

29. Nomenclature PracticeNomenclature Practice
Name this compound
CH
3 CH
3
CH
3
CH
3
Cl
1
5
2 43
9
6
8
7
9 carbons = nonane
Step #2: When alkane groups appear as substituents, they are named
by dropping the -ane and adding -yl.
CH
3
= methyl
chlorine = chloro

30. Nomenclature PracticeNomenclature Practice
Name this compound
CH
3 CH
3
CH
3
CH
3
Cl
1
5
2 43
9
6
8
7
9 carbons = nonane
CH
3
= methyl
chlorine = chloro
Step #3: The positions of substituent groups are
specified by numbering the longest chain of carbon
atoms sequentially, starting at the end closest to the
branching.
1 9NOT 9 1

31. Nomenclature PracticeNomenclature Practice
Name this compound
CH
3 CH
3
CH
3
CH
3
Cl
1
5
2 43
9
6
8
7
9 carbons = nonane
CH
3
= methyl
chlorine = chloro
Step #4: The location and name of each substituent are
followed by the root alkane name. The substituents are
listed in alphabetical order (irrespective of any prefix),
and the prefixes di-, tri-, etc. are used to indicate
multiple identical substituents.
2-chloro-3,6-dimethylnonane

33. Homework
•Do all relevant questions from book
•Complete worksheet.