Naming Organic Compounds Edited from : L. Scheffler Lincoln High School IB Chemistry

Originally compounds were named based on their source or use Many organic compounds were given common names which are still in use However many ambiguities resulted With the large number of organic compounds, a method for systematically naming them is very important Naming Organic Compounds 2

The International Union of Pure and Applied Chemists (IUPAC) developed a system for naming organic compounds. This system eliminated many of the ambiguities that plagued earlier naming systems Common names for many substances are still widely used IUPAC Names 3

A series of prefixes are used to designate the number of carbon atoms in a carbon chain Naming Hydrocarbons using the IUPAC System meth1 Chex6 C eth2 Chept7 C prop3 Coct8 C but4 Cnon9 C pent5 Cdec10 C 4

For straight chain hydrocarbons. The prefix indicates the number of carbon atoms. The suffix ane is added to designate that the compound is an alkane Naming Alkanes 5

For branched chain hydrocarbons, identify the longest consecutive (straight) chain first. Then name the side chains or branches. The name of the branches end in “yl” and go before the name of the straight chain Naming Alkanes with branched chains -methylpropane methyl butane dimethyl propane 6

Alkenes have one (or more) carbon to carbon double bonds When there are 4 or more carbon atoms in a chain, the location of the double bond is indicated by a number. Numbering the location of the double bond(s) takes precedence over the location of side chains Alkenes 1 butene 2-butene methylpropene 7

Naming Compounds With Functional Groups Various functional groups have unique suffixes that designate the functional group. The functional group takes precedence in numbering the carbon chain. Branches to the carbon chain are named in the usual manner. alcohols “anol” Amides “anamide” Aldehydes “anal” Amines “anamine” (can also be a prefix) Ketones “anone” Ethers “-oxyalkane” Acids “anoic acid” halohydrocarbons (prefix) Fluoro, bromo, chloro or iodo Esters “anoate” 8

Alcohols Suffix = “ol” Propan-1-ol Propan-2-ol 2-methylpropan-2-ol 9

Suffix = “al” Propanal Note that the aldeyhde group is always on an end carbon or carbon 1 Aldehydes and Alkanals 10

Suffix = “one” Propanone (also known as acetone) Butanone (also known as methyl ethyl ketone) Pentan-2-one (note the number is necessary Because the C=O could be on carbon 2 or carbon 3) Ketones or Alkanones 11

Suffix = “oic acid” Butanoic acid Note that the acid group (called a “carboxyl”) is always on an end carbon or carbon 1 Carboxylic Acids 12

Esters Suffix = “oate” Ethyl butanoate Butyl ethanoate There are two branches. The branch with the carbonyl gets the suffix Esters 13

Suffix = “amide” butanamide Note that the amide group is always on an end carbon or carbon 1 Amides 14

Suffix = “amine” Or prefix = “amino” Propylamine or 1-aminopropane 2-propylamine or 2-aminopropane 2-methyl-2-propylamine or 2-methyl -2- aminopropane Amines 15

prefixes = “fluoro, chloro, bromo, iodo” 1-bromopropane 2 chlorobutane 1,2 diiodoethane Cis 1,2difluroethene Trans 1,2 difluoroethene 1,1,2 trifluorothene Halohydrocarbons 16

Suffix = “oxy”on first branch Ethoxyethane (diethylether) Ethoxybutane (ethylbutyl ether) Ethers 17

Aromatic Compounds With Functional Groups Benzoic acid 2 hydroxybenzoic acid 3 bromobenzoic acid 18

Nitriles 19 Nitriles have a cyanide group. The name is based on the longest carbon chain that includes the carbon atom in the nitrile group.

Homologous Series 20 -Successive members differ by a CH 2 group. -Members can be represented by the same general formula. -C n H 2n+1 OH -Members show a gradation in physical properties -Trends can be seen in boiling point, density and viscosity -Members have similar chemical properties

Types of chemical formulas 21

Primary, secondary and tertiary compounds 22

Structural isomers 23 C 4 H 10 C4H8C4H8 C3H8OC3H8O

Saturated vs unsaturated

Index of hydrogen deficiency (IHD) -Uses the formula to tell you if there are multiple bonds and/or rings present -Generic formula: C c H h N n O o X x, X=halogen -IHD = 0.5 (2c + 2 – h – x + n) -Ex: C 4 H 8 O (2(4) + 2 – 8 – 0 + 0) -0.5 (2) = 1 -This means there is either a double bond or a ring that is part of this formula.

Calculate the IHD FormulaIHDName C 17 H 21 NO 4 cocaine C 27 H 46 Ocholesterol C6H7NC6H7NAniline (old pain killer and rocket fuel) C 15 H 10 ClN 3 O 3 Clonazepam (seizure medication)

Spectroscopy -Structural Analysis – description of how atoms are arranged -IR : Identify the bonds in a molecules -Mass Spec: determine fragmentation to identify arrangement -NMR: shows chemical environment of isotopes to give structural information (detected by radio waves)

Mass Spectrometry -Electron gun hits the species and removes an electron -Breaks molecule apart into recognizable chunks (fragments) -Fragmentation pattern provides useful evidence for structure of compound

Mass Spec.

-This table is in section 28 of data book

Mass Spec.

Infrared (IR) spectroscopy -All bonds vibrate and bend at a natural frequency (depending on strength of bond and masses of atoms) -Polar bonds will interact with IR

Infrared (IR) spectroscopy

Identify the bonds responsible for the peaks at A, B and C in the IR spectrum of X.

1 H NMR -Proton NMR. -Gives information on the different chemical environments of hydrogen atoms in a molecule -VERY common tool for organic chemists

H1 NMR -TMS (tetramethlsilane) is used as the standard (this peak is set to 0ppm) -Hydrogen nuclei in the different chemical environments have different chemical shifts (section 27 data booklet)

H1 NMR -Two different hydrogen environments are present in this molecule. -The integrated trace tells you how many hydrogens are in the same environment.