1. Organic Chemistry
Topic –
bonds
HONC

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. Homologous series/compounds (10.1.1)
related compounds that have the same functional group (groups of atoms found within molecules that are involved in the chemical reactions characteristic of those molecules)

5. differ from each other by a CH2 unit
can be represented by a general formula
examples:
CnH2n+2 (alkanes) or CnH2n (alkenes) or…

7. have similar chemical properties
have physical properties that vary in a regular manner as the number of carbon atoms present increases
Example: the alkanes

9. Trends in boiling points of members of a homologous series (10.1.2)
melting point and boiling point increase with more carbon atoms
Why?
intermolecular forces increase
adding a CH2 adds more electrons
this increases the Van der Waal’s forces
Alkane
Formula
Boiling Pt./oC
methane
CH4
-162.0
ethane
C2H6
-88.6
propane
C3H8
-42.2
butane
C4H10
-0.5
Intermolecular forces present & molar mass

11. Empirical, molecular & structural formulas (10.1.3)

12. simplest ratio of atoms in a molecule
Empirical Formula
Molecular Formula
CH4
CH3
C2H6
CH2O
C6H12O6
CH2
C4H8
C8H16
empirical formula
simplest ratio of atoms in a molecule
molecular formula
actual numbers of atoms in a molecule

13. 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
CH3CH2CH2CH2CH2CH3
or even CH3(CH2)4CH3
CH3CH(CH3)CH3 (this is not the molecule above)

14. condensed

15. skeletal formula not accepted in the IB for answers but often used
every “corner” represents a carbon
hydrogens are implied

16. Isomers (10.1.4)
(structural) isomers: compounds with the same molecular formula but different structure (arrangement of atoms)

17. different isomers are completely different compounds
have different physical properties such as melting point and boiling point

18. Structural Formulas for C4H10O Isomers

19. Alkanes
Structural formulas for the isomers of non-cyclic alkanes up to C6 (10.1.5)
hydrocarbon chains where all the bonds between carbons are SINGLE bonds
CnH2n+2
draw out and write the structural formulas for all isomers that can be formed by:
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
Richard Thornley
2:54

20. Naming the isomers (IUPAC) of non-cyclic alkanes up to C6 (10.1.6)
Richard Thornley 3:35
Determine the longest carbon chain
Use the prefix to denote the number carbons
Monkeys
Eat
Peeled
Bananas 1
Meth- 2
Eth- 3
Prop- 4
But- 5
Pent- 6
Hex-

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

22. 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)
CH3 is methyl
C2H5 is ethyl
C3H7 is propyl
And with 2 or more side chains:
use prefixes di-, tri-, tetra-, to indicate when there are multiple side chains of the same type
use commas to separate numbers and hyphens to separate numbers or letters.
name the side chains in alphabetical order

23. How about C5H12? The isomers are:
Pentane methyl-butane dimethyl-propane

24. Alkenes
Structural formulas for the isomers of the straight chain alkenes up to C6 (10.1.7)
alkenes have a double bond between two or more of the carbons
CnH2n
draw out and write the structural formulas for all isomers that can be formed by each
C2H4
C3H6
C4H8
C5H10
C6H12
Richard Thornley (1:37)

25. Nomenclature Practice
Name this compound 1
9 carbons = nonane 2 4 3 5 6 7 8 9
Step #1: For a branched hydrocarbon, the longest continuous chain of carbon atoms gives the root name for the hydrocarbon

26. Nomenclature Practice
Name this compound
9 carbons = nonane 1 2 4 3 5 6
CH3 = methyl 7
chlorine = chloro 8 9
Step #2: When alkane groups appear as substituents, they are named by dropping the -ane and adding -yl.

27. Nomenclature Practice
Name this compound
9 carbons = nonane 1 2 4 3 5 6
CH3 = methyl 7
chlorine = chloro 8 9 1 9
NOT 9 1
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.

28. Nomenclature Practice
Name this compound
9 carbons = nonane 1 2 4 3 5 6
CH3 = methyl 7
chlorine = chloro 8 9
2-chloro-3,6-dimethylnonane
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.

29. Naming the isomers (IUPAC) of straight chain alkenes up to C6 (10.1.8)
suffix changes to “-ene”
when there are 4 or more carbon atoms in a chain, the location of the double bond is indicated by a number
begin counting the carbons closest to the end with the C=C bond
numbering the location of the double bond(s) takes precedence over the location of any substituents
1-butene butene
but-1-ene but-2-ene

30. choose the correct ending
Naming Practice!!!
choose the correct ending
ene

31. determine the longest carbon chain
ene

32. assign numbers to each carbon
ene

33. assign numbers to each carbon
ene

34. attach prefix (according to # of carbons)
ene
1-hexene

35. determine name for side chains
ethyl
methyl
methyl
determine name for side chains
1-hexene
1-hexene

36. attach name of branches alphabetically
ethyl
methyl
methyl
attach name of branches alphabetically
2-ethyl-4-methyl-4-methyl-1-hexene
1-hexene

37. group similar branches
ethyl
methyl
methyl
group similar branches
2-ethyl-4-methyl-4-methyl-1-hexene
1-hexene

38. group similar branches
ethyl
methyl
methyl
group similar branches
2-ethyl-4,4-dimethyl-1-hexene
or 2-ethyl-4,4-dimethy hex-1-ene

39. propene
2,4-dimethyl-2-pentene
2,4-dimethyl pent-2-tene
2-butene

40. a) 3,3-dimethyl-1-pentene b) sameC H 3 C H C C C H C H C H 3 3 C H 3
c) 4,5 dimethyl-2-hexene