Organic Chemistry Topic 10.1 CHONCCHONC 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

Empirical, molecular & structural formulas 2

empirical formula – simplest ratio of atoms in a molecule molecular formula – actual numbers of atoms in a molecule Empirical Formula Molecular Formula CH 4 CH 3 C2H6C2H6C2H6C2H6 CH 2 O C 6 H 12 O 6 CH 2 C4H8C4H8C4H8C4H8 C 8 H 16

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 ) 4 CH 3 CH 3 CH(CH 3 ) CH 2 CH 3

condensed

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

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

ifferent isomers are different compounds different isomers are different compounds have different physical properties such as melting point and boiling point have different physical properties such as melting point and boiling point

Structural Formulas for C 4 H 10 O Isomers

Homologous series/compounds 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 CH 2 unit can be represented by a general formula – examples: C n H 2n+2 (alkanes) or C n H 2n (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 melting point and boiling point increase with more carbon atoms Why? – intermolecular forces increase – adding a CH 2 adds more electrons this increases the London dispersion forces AlkaneFormula Boiling Pt./ o C methane CH ethane C2H6C2H6C2H6C2H propane C3H8C3H8C3H8C3H butane C 4 H

hydrocarbon chains where all the bonds between carbons are SINGLE bonds hydrocarbon chains where all the bonds between carbons are SINGLE bonds C n H 2n+2 draw out and write the structural formulas for all isomers that can be formed by: – CH 4 –C2H6–C2H6 –C3H8–C3H8 – C 4 H 10 – C 5 H 12 – C 6 H 14 Richard Thornley 2:54 Structural formulas for the isomers of non- cyclic alkanes up to C 6 Alkanes

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

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

Nomenclature Practice Name this compound Step #1: For a branched hydrocarbon, the longest continuous chain of carbon atoms gives the root name for the hydrocarbon carbons = nonane

Nomenclature Practice Name this compound 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

Nomenclature Practice Name this compound 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. 19 NOT 91

Nomenclature Practice Name this compound 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

Structural formulas for the isomers of the straight chain alkenes up to C 6 alkenes have a double bond between two or more of the carbons C n H 2n draw out and write the structural formulas for all isomers that can be formed by each –C2H4–C2H4 –C3H6–C3H6 –C4H8–C4H8 – C 5 H 10 – C 6 H 12 Alkenes Richard Thornley (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-butene but-1-ene but-2-ene Naming the isomers (IUPAC) of straight chain alkenes up to C 6

ene Naming Practice!!! choose the correct ending

ene determine the longest carbon chain with the double bond

assign numbers to each carbon ene

assign numbers to each carbon ene

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

determine name for side chains 1-hexene ethyl methyl

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

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

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

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

b) same c) 4,5 dimethyl-2-hexene a) 3,3-dimethyl-1-pentene CHCHCH 3 CH 3 CC CH 3 CH 3