Organic Naming RulesAP Chemistry 439For complete Rules go to:http://www.acdlabs.com/iupac/nomenclature/

Organic CompoundsConsist of mainly four elementsCarbonHydrogenOxygenNitrogen

Why Do We Need a Separate Set of Rules?Examine some typical organic compoundsCH4C2H6Name these using typical covalent rules

Carbon tetrahydrideDicarbon hexahydride

So?That wasnt so bad, right?How about these:C4H10C5H12See my point?Tetracarbon decahydridePentacarbon ??? hydride

IsomersIf thats not enough, how about this one: Formula?C4H10Formula?C4H10Different Structure

Same Formula

Overall ProblemsMemorizing too many prefixes for large numbersDifferent chemicals having the same formulasKeep in mind that thus far weve only dealt with TWO different elements!

So what to do?Number of hydrogens is going to be the same, regardless of isomerismC5H12C5H12C5H12

SolutionSince number of hydrogens dont change with isomerism, why bother naming them?Name the molecule simply based on number of CARBONSWe can always add prefixes or suffixes later for differentiation

Name based on number of Carbons12345678910MethaneEthanePropaneButanePentaneHexaneHeptaneOctaneNonaneDecane

Did that Really Help?Carbon tetrahydride becomes:MethaneDicarbon hexahydride becomes:EthaneCH4C2H6Octacarbon ???hydride becomes:OctaneC8H18

BranchesStraight-chain alkanes (Just C & H with single bonds) are now easy

C4H10 ButaneBut how do we deal with branches?C4H10 ????

Rules pt. 2Identify the longest unbranched chain of carbonsName it as normalIdentify the branchName it but give it a yl suffixPut the names of all branches first, then put name of longest chain

ExampleLongest unbranched chain of carbons is three longpropanemethylMethyl Propane

PracticeMethyl butaneEthyl pentane

One More PracticeMethyl Butane

Be CarefulHexaneMethyl Hexane

A Small WrinkleMethyl PentaneMethyl PentaneThese are different molecules, though!!!

So Now What?Since two different molecules cant have the same name, we must differentiateIf we look closely, though, the only difference between them is the position of the methyl group

PositioningMethyl PentaneMethyl PentaneSo2-3-

Rules pt. 3Identify the longest unbranched chain of carbonsName it as normalIdentify the branchName it but give it a yl suffixPut the names of all branches first, then put name of longest chainPut the number of the carbon the branch is on (start numbering from the closest single end)

Practice2-methyl heptane4-methyl octane2-methyl hexane

Multiple BranchesSo far weve only had one branchWhat happens when there are multple branches?Just add a prefix to indicate the number of a particular type of branch

Practiceheptanemethylmethyl2-2-2-methyl, 2-methyl heptaneSounds redundant2,2 dimethyl heptane

More Practice2, 6-dimethyl octane3 ethyl-2,4-dimethyl pentane

Is your arm sore yet?Are you sick to death of writing all those carbons?Even worse, are you sick of writing all those Hydrogens?How about this

Shorthand notationKeep in mind that we have been ignoring the hydrogens for a long time.Our names have been based entirely on the positioning of the carbons.So lets now ignore the hydrogens completely!

Is it that easy?

One More3-ethyl-2,4 dimethyl hexane

So is that it?Not even close!!There are literally millions of different organic compounds.What else can we do to make things more complicated?

RingsThus far we have dealt with chains that are straight or branched.If hydrocarbons are long enough, one end can wrap around and link up with itself!We call these cyclic hydrocarbons.

Cyclic HydrocarbonsName the molecule as normalAdd the prefix cyclo- to the front of the name of the longest chainStart numbering from the most important branch in the ring

ExamplesCyclohexaneCyclooctane

More ExamplesMethyl cyclopentane1,2 dimethyl cyclohexane

Try These1 ethyl, 3 methyl cyclobutane3 methyl, 1 propyl cylclohexane

Multiple BondsSo far, even with the cyclic structures we have dealt only with single bondsCarbon can make multiple bonds to another carbonThis changes the nameWhy?

Examine StructuresC2H6Ethane- notice that each carbon has four bondsWhat will happen to the structure if we double bond the two carbons?C2H4Each carbon still has four bonds BUT now the hydrogens have changed!!

Naming molecules with multiple bondsName the molecule as normalChange the suffix of the longest chain nameDouble bonds = eneTriple bonds = yneUse numbering and prefixes for positioning and multiple multiple bonds.

So.C2H6C2H4C2H2ethaneetheneethyne

Practice3 methyl-1-pentene2-heptene1-butene

How about in Shorthand?2 pentene

Practice!Methyl propene2,4-dimethyl-2-pentene3-ethyl-2,4,4-trimethyl-1-pentene

Tough Ones2 methyl 1,3 butadiene1,2 dimethyl-1,4 cyclohexadiene

Triples?3, 3-dimethyl-1-butyne1,4 cyclohexadiyne

So thats it, right?Not even close, bud.All this.all this was just for two elements, carbon and hydrogen!!We havent even dealt with any of the others, yet.

Wait!! Dont jump!!Get off that bridge.Its not that bad provided we arrange things in an organized fashion!

Functional GroupsNature has done us a favor.There are many common groups that we can organized or file into different categories.Then we can name them based on these categories.

Functional GroupsA group of atoms that, when added to a hydrocarbon chain, alter the chemical properties of the chain.Just a few different functional groups to know

Functional GroupsHalogensAlcoholsEthersAldehydesKetonesCarboxylic AcidsEstersAmines

R-F, R-Cl, R-Br, R-IR-OHR-O-RR-COHR-CO-RR-COOHR-COO-RR-NH2

HalidesFluorides, Chlorides, Bromides, and IodidesSimply name the molecule as normal but add the prefix Fluoro, Chloro, Bromo, or Iodo as necessary

Halides2, 3 dichlorohexane3, 3 diiodo-1-pentene

AlcoholsR-OHName like normal except add an ol suffix

Alcohols2 propanolethanol1cyclobutenol

EthersR-O-RName two R groups with yl endingsEnd name in ether

EthersDimethyl etherEthyl methyl ether

AldehydeR-COHThis is a carbon to oxygen double bond with a hydrogen at the end.Name as normal except use a -al suffix

Aldehydesbutanal3,3 dichloropentanal

KetonesR-CO-RThis is a carbon to oxygen double bond but in the center of a hydrocarbon chain rather than the endName as normal but give it a -one suffix

Ketonespropanone2 hexanone

Carboxylic AcidsR-COOH or R-CO2HThis is a carbon to oxygn double bond with the same carbon single-bonded to an OH group.Name as normal except give it the suffix -anoic acid.HC2H3O2

Carboxylic AcidsButanoic acid3-Fluoropropanoic acid

EstersR-COO-RThis is a carbon to oxygen double bond with a carbon to oxygen single bonded to another single bonded carbonName by given secondary branch -yl suffix and main branch -anoate suffix.

EstersmethylpentanoateMethyl Pentanoate

EstersButyl propanoateMethyl hexanoate

AminesR-NH2Name the R group or groups with -yl endingsAdd the word amine

AminesMethyl amineDimethyl amine

Summary

SummaryAlkanesAlkenesAlkynesHalides AlcoholsEthersAldehydesKetonesCarboxylic AcidsEstersAmines--ane=-ene -yneR-X-oR-OH-olR-O-R-yl etherR-COH-alR-CO-R-oneR-COOH-anoic acidR-COO-R-yl -anoateR-NH2-yl amine

Can You Do This?YES!It takes:MemorizationPracticePracticePracticePracticeAnd, oh yesPractice!

Does anyone know the prefixes beyond ten?Definition: Isomer- chemicals that have the same formula but different structuresThe number of hydrogens will change later but for right now with only single bonds, they will always be the same.What is the equation for C & H in an alkane? CnH2n+2Note the differences between this list and the covalent prefixes. Only the first four are diffferent.You can turn corners, go up, down, left, right, zig-zag, or do what ever you want provided you dont double back on yourself.Remember that molecules dont care about left or right, top or bottom.Again, the molecule on the left is 2-methyl pentane NOT 4-methyl pentane. Molecules dont care about left or right so we start numbering from the closest side.Technically you should but branches in alphabetical order but I wont be that picky.Each end and each point represents a carbon atom. The hydrogen atoms are assumed to be there.Multiple bonds, rings, other atomsNote that a number is not needed on the first example.Note that numbers are now needed to indicate position. It doesnt matter, though which is 1 and which is 2Different structures need different namesAlkenes are molecules with double bondsAlkynes are molecules with triple bondsAlkanes are molecules only with single bonds