organic chemistry topic 10.1.1 – 10.1.8 choncchonc 4 1 2 3 4 bonds
TRANSCRIPT
Organic Chemistry
Topic 10.1.1 – 10.1.8
HONCC
1 2 3 44 bonds
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
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)
• differ from each other by a CH2 unit• can be represented by a general
formula– examples:
• CnH2n+2 (alkanes) or CnH2n (alkenes) or…
• have similar chemical properties• have physical properties that vary
in a regular manner as the number of carbon atoms increases– Example: the alkanes
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
AlkaneAlkane FormulFormulaa
Boiling Boiling Pt./Pt./ooCC
methanmethanee
CHCH44 -162.0-162.0
ethaneethane CC22HH66 -88.6-88.6
propanpropanee
CC33HH88 -42.2-42.2
butanebutane CC44HH1010 -0.5-0.5
Empirical, molecular & structural formulas (10.1.3)
• empirical formula– simplest ratio
of atoms in a molecule
• molecular formula– actual
numbers of atoms in a molecule
Empirical Empirical FormulaFormula
MoleculaMolecular r
FormulaFormula
CHCH44 CHCH44
CHCH33 CC22HH66
CHCH22OO CC66HH1212OO66
CHCH22 CC44HH88
CHCH22 CC88HH1616
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
condensed
skeletal formula– not accepted in the IB for answers but
often used in questions– every “corner” represents a carbon– hydrogens are implied
Isomers (10.1.4)
• (structural) isomers: compounds with the same molecular formula but different structure (arrangement of atoms)
• different isomers are completely different ifferent isomers are completely different compoundscompounds
• have different physical properties such as have different physical properties such as melting point and boiling pointmelting point and boiling point
Structural Formulas
for C4H10O Isomers
• hydrocarbon chains where all the bonds between hydrocarbon chains where all the bonds between carbons are SINGLE bondscarbons 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 10.1.5 2:54
Structural formulas for the isomers of non-cyclic alkanes up to C6 (10.1.5)
Alkanes
1. Richard Thornley 3:352. Determine the longest carbon chain
– Use the prefix to denote the number carbons
Naming the isomers (IUPAC) of non-cyclic alkanes up to C6 (10.1.6)
11 MMeth-eth-
22 EEth-th-
33 PProp-rop-
44 BBut-ut-
55 Pent-Pent-
66 Hex-Hex-
Monkeys
Eat
Peeled
Bananas
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)
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)
• CH3 is methyl
• C2H5 is ethyl
• C3H7 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 type6. use commas to separate numbers and
hyphens to separate numbers or letters.7. name the side chains in alphabetical order
• How about C5H12? The isomers are:
Pentane 2-methyl-butane 2,2-dimethyl propane
Nomenclature PracticeNomenclature Practice
CH3 CH3
CH3
CH3
Cl
Name this compound
Step #1: For a branched hydrocarbon, the longest continuous chain of carbon atoms gives the root name for the hydrocarbon
152 43
9
6
87
9 carbons = nonane
Nomenclature PracticeNomenclature PracticeName this compound
CH3 CH3
CH3
CH3
Cl
152 43
9
6
87
9 carbons = nonane
Step #2: When alkane groups appear as substituents, they are named by dropping the -ane and adding -yl.
CH3 = methyl
chlorine = chloro
Nomenclature PracticeNomenclature PracticeName this compound
CH3 CH3
CH3
CH3
Cl
152 43
9
6
87
9 carbons = nonane
CH3 = 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 9 NOT 9 1
Nomenclature PracticeNomenclature PracticeName this compound
CH3 CH3
CH3
CH3
Cl
152 43
9
6
87
9 carbons = nonane
CH3 = 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
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
Alkenes
Richard Thornley 10.1.7 (1:37)
1. suffix changes to “-ene”2. when there are 4 or more carbon atoms
in a chain, the location of the double bond is indicated by a number
3. 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 2-butenebut-1-ene but-2-ene
Naming the isomers (IUPAC) of straight chain alkenes up to C6 (10.1.8)
ene
Naming Practice!!!
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
choose the correct ending
ene
determine the longest carbon chain with the double bond
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
assign numbers to each carbon
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
ene
assign numbers to each carbon
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
ene
1-hexene ene
attach prefix (according to # of carbons)
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
determine name for side chains
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
1-hexene 1-hexene
ethyl
methyl
methyl
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
2-ethyl-4-methyl-4-methyl-1-hexene
ethyl
methyl
methylattach name of branches alphabetically
group similar branches
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
2-ethyl-4-methyl-4-methyl-1-hexene
ethyl
methyl
methyl
group similar branches
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
2-ethyl-4,4-dimethyl-1-hexene
or 2-ethyl-4,4-dimethyl hex-1-ene
ethyl
methyl
methyl
2-butene
propene
CH3 CH CH2
CH3 CH CH CH3
CH3 CH CH C
CH3 CH3
CH3
2,4-dimethyl-2-pentene2,4-dimethyl pent-2-tene
b) same
c) 4,5 dimethyl-2-hexene
a) 3,3-dimethyl-1-pentene
CH2 CH C CH2 CH3
CH3
CH3
CH3 C CH CH2
CH3
CH2 CH3
CH CH CH3
CH3
CC
CH3
CH3