NAMING Organic Chemistry IUPAC

L.O 11.4.2.1 recognise and understand the use of a variety of formula types 11.4.2.2 understand that an organic compound generally consists of a hydrocarbon component plus a functional group 11.4.2.3 recognise the common functional groups 11.4.2.4 understand and be able to use the IUPAC nomenclature 11.4.2.5 understand the formation of homologous series and the similarity of properties 11.4.2.6 understand why isomerism occurs and be able to draw isomers for given molecular formulas 11.4.2.7 understand the formation of sigma and pi bonds and know their occurrence and the implication for molecular shapes 11.4.2.8 understand the concept of saturation and apply it to the alkanes as a ‘base’ homologous series 11.4.2.9 recognise the importance of alkanes as fuels, their combustion products and the environmental effects of burning hydrocarbon fuels 11.4.2.10 recall details of the fractionation of oil and the uses of the fractions 11.4.2.11 understand homolytic bond fission and the formation of free radicals 11.4.2.12 understand catalytic cracking and thermal cracking in terms of a free radical process 11.4.2.13 know and understand the mechanism of photochemical chlorination

TYPES OF FORMULAE - 1 Fuse School 5 min. MF, EF, Displayed Formula https://www.youtube.com/watch?v=9SX-iWpi98g MOLECULAR FORMULA C4H10 The exact number of atoms of each element present in the molecule EMPIRICAL FORMULA C2H5 The simplest whole number ratio of atoms in the molecule STRUCTURAL FORMULA CH3CH2CH2CH3 CH3CH(CH3)CH3 The minimal detail using conventional groups, for an unambiguous structure there are two possible structures DISPLAYED FORMULA Shows both the relative placing of atoms and the number of bonds between them

A systematic name has two main parts. I.U.P.A.C. NOMENCLATURE L.O. Understand and be able to use the IUPAC nomenclature A systematic name has two main parts. Number of carbon atoms in longest chain and identity of any side-chain substituents. Apart from the first four, which have trivial names, the number of carbons atoms is indicated by a prefix derived from the Greek numbering system. The ending -ane is the same as they are all alkanes. Prefix C atoms Alkane meth- 1 methane eth- 2 ethane prop- 3 propane but- 4 butane pent- 5 pentane hex- 6 hexane hept- 7 heptane oct- 8 octane non- 9 nonane dec- 10 decane

Alkanes - Nomenclature The name of every organic molecule has 3 parts: The parent name indicates the number of carbons in the longest continuous chain. The suffix indicates what functional group is present. The prefix tells us the identity, location, and number of substituents attached to the carbon chain.

Alkanes - Nomenclature 1. Find the parent carbon chain and add the suffix. Note that it does not matter if the chain is straight or it bends.

Alkanes - Nomenclature Also note that if there are two chains of equal length, pick the chain with more substituents. In the following example, two different chains in the same alkane have seven C atoms. We circle the longest continuous chain as shown in the diagram on the left, since this results in the greater number of substituents.

Alkanes - Nomenclature 2. Number the atoms in the carbon chain to give the first substituent the lowest number.

Alkanes - Nomenclature When numbering a carbon chain results in the same numbers from either end of the chain, assign the lower number alphabetically to the first substituent.

Alkanes - Nomenclature Cycloalkanes are named by using similar rules, but the prefix cyclo- immediately precedes the name of the parent. 1. Find the parent cycloalkane.

Alkanes - Nomenclature 2. Name and number the substituents. No number is needed to indicate the location of a single substituent. For rings with more than one substituent, begin numbering at one substituent and proceed around the ring to give the second substituent the lowest number.

Alkanes - Nomenclature With two different substituents, number the ring to assign the lower number to the substituents alphabetically. Note the special case of an alkane composed of both a ring and a long chain. If the number of carbons in the ring is greater than or equal to the number of carbons in the longest chain, the compound is named as a cycloalkane.

I.U.P.A.C. NOMENCLATURE CH3 CH2 CH Now this If identical side-chains appear more than once, prefix with di, tri, tetra, penta, hexa Numbers are separated from names by a HYPHEN e.g. 2-methylheptane Numbers are separated from numbers by a COMMA e.g. 2,3-dimethylbutane Try this compound Example longest chain 8 (it is an octane) 3,4,6 are the numbers NOT 3,5,6 order is ethyl, methyl, propyl 3-ethyl-5-methyl-4-propyloctane CH3 CH2 CH Now this 2-chloro-3,6-dimethylnonane

Rules for Naming Alkanes (Nomenclature) The numbering starts at the end closest to the branching. The side chains end in yl. —CH3 Methyl 1 —CH2CH3 Ethyl 2 3 4 —CH2CH2CH3 Propyl Methyl

NAMING ALKENES Length In alkenes the principal chain is not always the longest chain It must contain the double bond the name ends in -ENE Position Count from one end as with alkanes. Indicated by the lower numbered carbon atom on one end of the C=C bond 5 4 3 2 1 CH3CH2CH=CHCH3 is pent-2-ene (NOT pent-3-ene) Side-chain Similar to alkanes position is based on the number allocated to the double bond 1 2 3 4 1 2 3 4 CH2 = CH(CH3)CH2CH3 CH2 = CHCH(CH3)CH3 2-methylbut-1-ene 3-methylbut-1-ene

How long is the longest chain? I.U.P.A.C. NOMENCLATURE How long is the longest chain? Look at the structures and work out how many carbon atoms are in the longest chain. CH2 CH3 CH THE ANSWERS ARE ON THE NEXT SLIDE CH2 CH3 CH CH3 CH CH2

Apply the rules and name these alkanes I.U.P.A.C. NOMENCLATURE I.U.P.A.C. NOMENCLATURE Apply the rules and name these alkanes Longest chain = 5 so it is a pentane A CH3, methyl, group is attached to the third carbon from one end... 3-methylpentane CH2 CH3 CH Longest chain = 6 so it is a hexane A CH3, methyl, group is attached to the second carbon from one end... 2-methylhexane CH2 CH3 CH Longest chain = 6 so it is a hexane CH3, methyl, groups are attached to the third and fourth carbon atoms (whichever end you count from). 3,4-dimethylhexane CH3 CH CH2

Alkynes - Nomenclature Alkynes are named in the same general way that alkenes are named; just change the suffix to –yne. Choose the longest continuous chain that contains both atoms of the triple bond and number the chain to give the triple bond the lower number.

Cyclic Alkanes Cyclopropane, C3H6 Cyclobutane, C4H8 Cyclopentane, C5H10 Cyclohexane, C6H12 Cycloheptane, C7H14 Remember, explicit hydrogens are left out

-OH -COOH -CHO -C- -O- -C-O -N- -C-NH Alcohols Organic acids Aldehydes Ketones Ethers Esters Amines Amides -OH hydroxyl -COOH carboxyl -CHO carbonyl O -C- -O- O -C-O -N- O -C-NH

Alkyl Halides - Nomenclature

Alcohols - Nomenclature