Organic Chemistry - Study of carbon-based compounds

1) Introduction to Carbon*Carbon has four valence electrons (2-4) so it will need 4 covalent bonds to fulfill octet* Tetrahedral shape

Properties of Organic Compounds1) Many are non-polar molecules2) Weak IMF’s3) Low melting and boiling points4) Insoluble in water5) React slowly

Table Q = Homologous Series of HydrocarbonsHomologous: compounds that vary by 1 carbon atomHydrocarbon: compounds composed of only hydrogen and carbon atoms

Alkanes Alkenes Alkynes* all C-C bonds are * one C=C double bond * one C≡C triple bond,

single bonds rest are single bonds rest are single bonds

*SATURATED *UNSATURATED *UNSATURATEDcompound compound compound

2) Table P: PrefixesReference Table P contains the prefix for the organic compound name. According to how many carbons are in the chain, the name will start with the appropriate prefixExamples:

4 C’s = but –2 C’s = eth –7 C’s = hept –10 C’s = dec –

3) Table Q: Homologous Series of HydrocarbonsThis table will help you to finish the name of the organic hydrocarbon compound.

- If the compound has all single bonds, it is an alkane and will end in –ane- If the compound has one double bond in the chain, it is an alkane and will end in –ene- If the compound has one triple bond in the chain, it is an alkane and will end in –yne

A. Alkanes – general formula CnH2n+2 where “n” is the number of carbon atoms

Ex 1) n = 2 Ex 2) butane Ex 3)

C2H6 C4H10

Ethane Butane

C5H12

Pentane

B. Alkenes – general formula CnH2n where “n” is the number of carbon atoms* need to provide the number of the carbon for which the double bond follows* can number L ‡ R or L R in order to give the lowest possible number for the double bond

Ex 1) n = 3 Ex 2) 3 - hexene Ex 3)

C3H6 C6H12 4 3 2 1

1 2 3 4

1 - Propene

C4H8

1 – butene

C. Alkynes – general formula CnH2n - 2 where “n” is the number of carbon atoms* need to provide the number of the carbon for which the triple bond follows* can number L ‡ R or L R in order to give the lowest possible number for the triple bond

Ex 1) n = 7 Ex 2) 2 - octyne

C7H12 C8H14

3 – heptyne

1 2 3 8 7 6 5 4 3 2 1

D. Branched HydrocarbonsOrganic compounds can have small chains called “branches” of carbon atoms off the main carbon chain. These branches are to be named separate from the main carbon chain, and will precede the name of the main carbon chain.

Rules for Branches: 1) Number the main chain so that the carbon number that the branch is on is the lowest possible number

2) Count number of carbons in each branch3) Use Table P for the branch prefix 4) Branch endings are –yl5) Provide the number of the main chain carbon that the branch is on, name the branch, and then name the main carbon chain

Ex) Ex)

5 4 3 2 1 1 2 3 4 5

The main chain is pentane- On the 2nd carbon is a methyl group- On the 3rd carbon is an ethyl group The main chain is pentane

- On the 2nd carbon is a methyl groupName = 2-methyl 3-ethyl pentane - On the 2rd carbon is a methyl group

Name = 2-methyl 2-methyl pentaneOR 2,2 dimethyl pentane

Ex) 2-propyl pentane Ex) 3-ethyl -3-methyl hexane

Start with pentane – main chain (5 C’s) Start with hexane – main chain (6 C’s)- On 2nd C in that chain, there is a 3-C branch - On 3rd C in that chain, there is a 2-C branch

- On 3rd C in that chain, there is also a 1-C branch

6 5 4 3 2 1

4) Functional Groups (Reference Table R)Atoms or groups of atoms other than Hydrogen (H) that are on a carbon-based chain

- typically Oxygen, Nitrogen and Halogens are added to the chain- presence of these elements on the carbon chain changes the physical and chemical properties

A. HalidesOne or more group 17 elements (F, Cl, Br or I) will replace a H atom on the carbon chain

To Name: Provide number of what carbon atom in the chain the halogen is onUse prefix listed on table RName main chain as usual

Ex) Main chain has 4 C’s, on 2nd C is Fluorine

1 2 3 42-fluoro-butane

To Draw: Start with main chain name to draw carbon chainDetermine what halogen(s) are placed on the chainUse numbers given to identify where on the chain the halogen(s) placed

Ex) 2,2-dichloro-pentane

Main chain is 5 carbon atoms Prefix for chlorine is chloro-On the 2nd carbon are 2 chlorine atoms

B. EtherSeries of organic compounds in which 2 carbon chains are joined together by an oxygen atom bonded between two carbon atoms

To Name: Treat the two branches as chains (ends in –yl)Name the chain on the left first, followed by the chain on the right, followed by the word “ether”

Ex) Ethyl ethyl ether

ethyl ethyl

To Draw: Draw an O atomTo left of the Oxygen place the first branch, the second branch to the right

butyl ethylEx) Butyl ethyl ether

C. AlcoholOne or more hydrogen atoms is replaced by an –OH group* This does NOT make it a base because there is no metal with the –OH group

Classifications:- Monohydroxy alcohol - Dihydroxy alcohol - Trihydroxy alcohol

there is one –OH group there are two –OH groups there are three –OH groups on the chain on the chain on the chain

- Primary alcohol = -OH group is on an end carbon of the chain

- Secondary alcohol = -OH group is on a middle carbon of the chain

- Tertiary alcohol = -OH group is on a middle carbon of the chain that also has a branch on it

To Name: Provide number(s) of what carbon atom in the main chain the -OH is onName main chain as usual, but end in -ol

Ex) 1-butanol

4 3 2 1

To Draw: Start with main chain name to draw carbon chainDetermine where the –OH group(s) is placed on the chain

Ex) 2 – propanol

Prop- prefix tells there are 3 C’s in chain-ol ending tells what functional group is on chain2 – tells what # C the –OH group is on

D. AldehydeA beginning or ending carbon atom is double bonded to an oxygen atom instead of a H atom

To Name: Name main chain as usual, but end in –alNo number needed

Ex) pentanal

To Draw: Start with main chain name to draw carbon chainPlace the double bonded oxygen on an end or beginning carbon of the chain

Ex) propanal

Prop- prefix tells there are 3 C’s in chain-al ending tells double bonded O atom is present

E. KetoneA carbon atom somewhere in the middle of the chain has a double bonded to an oxygen atom

To Name: Name main chain as usual, but end in –oneProvide the (lowest) number of the carbon in the chain that the O atom is on

Ex) 2 - pentanone

To Draw: Start with main chain name to draw carbon chainThe number provided tells you what carbon atom the double bonded O atom is on

Ex) 2 - butanone

But- prefix tells there are 34 C’s in chain-one ending tells double bonded O atom is present2 tells what # carbon atom the O atom is on

F. Organic AcidAn organic compound on which a beginning or ending carbon has both an –OH group and a double bonded oxygen atom on it

To Name: Name main chain as usual, but end in –oic acidNo number needed

Ex) Propanoic acid

To Draw: Start with main chain name to draw carbon chainPlace the double bonded oxygen and –OH group on an end or beginning carbon of the chain

Ex) butanoic acid

But- prefix tells there are 4 C’s in chain-oic acid ending tells that there is a double bonded O atom and an –OH group presenttogether on an ending or beginning carbon

G. EsterThis organic compound both a double bonded O atom and a single bonded O atom on a single carbon in the main chain

To Name: The branch name comes first. - This is the carbon chain that is off of the oxygen atom in the chain - Prefix comes from Table P; ends in -yl

The remaining carbons on the opposite side make up the main chain - prefix comes from Table P- ending is –oate

Ex) Ethyl ethanoate

main chain branchethyl

To Draw: Start with the branch. Use prefix to tell you how many C atoms are neededFollow that chain of carbons with an O atomFill in the opposite side of the oxygen with C atoms from the main chain nameThe carbon that is attached to the O and the main chain carbon also needs a double bonded O

Ex) butyl ethanoate

Start by drawing the ester functional groupButyl tells there is a 4 C’s branch – those carbons go to the right of the oxygenEthanoate is the main chain- eth- is two carbons, one of which is double bonded to the O

H. AmineA hydrogen atom on the carbon chain is replaced by a Nitrogen amine group (-NH2)

To Name: Provide number(s) of what carbon atom on the main chain the –NH2 group is onName main chain as usual, but end in -amine

Ex) 1-ethanamine

1 2

To Draw: Start with main chain name to draw carbon chainUse the number given and place the –NH2 group(s) on the correct carbon

Ex) 1 – butanamine

But- prefix tells there are 4 C’s in main chain-amine ending tells what functional group is on chain (-NH2)1 – tells what # C the –NH2 group is on

I. AmideA beginning or ending carbon on the main chain has an –NH2 group AND a double bonded O atom

To Name: Name main chain as usual, but end in -amideEx)

butanamide

To Draw: Start with main chain name to draw carbon chainPlace an –NH2 group(s) and a double bonded O atom on a beginning or ending carbon

Ex) ethanamide

Eth- prefix tells there are 2 C’s in main chain-amide ending tells what functional groups are on chain the place amide functional groups on a beginning or ending carbon on the chain

5) Isomers

Examples:

C5H12 C2H6O

6) Organic Reactions

Hydrocarbons participate in a variety of chemical reactions. They are described below.

Combustion. Fossil fuels such as the gasoline used in automobiles or the propane used in gas barbecues are hydrocarbons.Whentheyburn,theyreleasecarbondioxideandwater.(C3H8+5O2‡ 3CO2+4H2O).Ofcourse,whenthereisinsufficientoxygen,asin anautomobileengine,thecarbondoesnotoxidizecompletely,andcarbonmonoxideandwaterforms.(2C8H18+17O2‡ 16CO+18H2O).Thatiswhyautomobileexhaustcontainscarbonmonoxide.

Substitution.Saturatedhydrocarbonshavealltheirbondingsitesfilledwithhydrogen.Theonlywaytoattachanyotherelementstothecarbonchainofasaturatedhydrocarbonistoreplacethehydrogen.Thereplacementofthehydrogenwithanotherelementiscalledsubstitution.Thediagramtotherightshowshalogensubstitution.

Addition.Whenthereisapointofunsaturation,itispossibletoaddelementstothehydrocarbonchainatthatpointwithoutremovinganyhydrogens.Thisiscalledaddition.Unsaturatedbondsaremorereactivethansaturatedbondsandalkynesareevenmorereactivethanalkenes,soadditionofhalogensoccursatroomtemperature.Additionofhydrogentoanalkeneoranalkyne(orothercarboncompoundswithdoubleortriplebonds)iscalledhydrogenation.Itistheprocessedusedtomakemargarinefromvegetableoil.

Fermentation.Beveragealcoholisformedbyyeast.Itformsasaresultoftheenzymaticbreakdownoforganicmoleculesduringanaerobicrespiration.

Esterification.Esterificationistheformationofesters(RCOOR).Estersformfromareactionbetweenanorganicacidandanalcohol.Thealcoholandacidjoinbydehydrationsynthesis.Thereactionlookssimilartoanacidbaseneutralization.Estersareresponsibleforfruitflavoringsandaromasofflowers.

Theyaresynthesizedasartificialflavors.Lipids(fatsandoils)areformedbyesterificationofglycerol(1,2,3-propanetriol)byfattyacids(longchainorganicacids)

Saponification.Saponificationisthehydrolysisoffatsbybases.Whensodiumhydroxidereactswithafatitproducesorganicsaltscalledsoapsplusglycerolasabyproduct.Thereactionlooksmuchlikethereverseoftheformationofthefat,exceptthatthefattyacidbecomesasodiumsalt[Na+CH3(CH2)nCOO–].

Polymerization.Polymerizationistheformationoflargemoleculesfromrepeatingunitsofsmallerones.Apolymerisalargemoleculeformedfrommanysmaller,repeatingunitsormonomers.Polymerscanformbycondensation– joiningmonomersbydehydrationsynthesis.Condensationpolymersmusthaveatleasttwofunctionalgroups.Theprocesscanberepeatedtoformlongchainpolymers.Examplesincludesilicones,polyesters,polyamides,phenolicplastics,andnylons.

Additionpolymerization involvesopeningupdoubleandtriplebondsofunsaturatedhydrocarbons.Examplesincludevinylplastics- polyethyleneandpolystyrene.