Organic Chemistry Topic 10

Uniqueness of carbon Up to 4 bonds with other atoms Single, double and triple bonds Stable covalent bonds C-C or C-H Can form chains and rings Octet cannot expand so not as reactive

Describe the features of an homologous series Organic means carbon based compounds Alkanes C, H all single bonds CnH2n+2 Alcohols have OH group bonded to C CnH2n+1OH

Features of an homologous series Same functional group Same general formula Successive members add CH2 Gradation of physical properties Similar chemical properties Question 1 and 2

Longer chains are stickier and have higher boiling points (bp) Question 3

Formulas ethane Empirical CH3 Molecular C2H6 Structural full and condensed

animation

Try ethanoic acid

Try glucose empirical formula CH2O Mr = 180

conventions R or R‘ used for hydrocarbon part ROH Benzene ring

4 single bonds is tetrahedral 109.5o not 90o, tetrahedral 3 bonds no lone pairs form 120o, triangular planer Sterochemical formula wedge = forward of a page, dotted line = behind

nomenclature Learn names of 1-6 carbons Rule #1 Name the longest chain Page 370 in your book Rule #1 Name the longest chain Build pentane and show how it rotates around a single bond

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#2 Use the functional group ending as the suffix of the name page 371 in the book -ane, -ene, -anol,-anone, -anoic acid

Name the side chain Methyl, ethyl, propyl Build 2-methyl butane This is an isomer of pentane Use the lowest # possible to number the carbon it is on What is 4-methyl pentane?

Use prefixes di-, tri-,tetra- to represent more than one side chain in alphabetical order 1,2 dichloropropane

1-chloro-2-methylpropane (notice alphabetical order)

Propan-2-ol

But-1-ene

If a functional group can only be in one place leave off the number Like propene

Butanoic acid

Propanone

Name the following a) CH3CH2CH2COOH b) CHCl2CH2CH3 c) CH3CH2COCH3

Draw the structural formulas of the following molecules a) hexanoic acid b) butanal

Do questions 4-6 Handout on nomenclature Do questions 1-4 pages 374-5

Aromatic groups Para dichloro benzene

Structural isomers Same molecular formula, different arrangement of atoms Different structural formula Butane and 2-methylpropane

Draw and name all the isomers of pentane Start with the straight chain and progressively pull off the ends

Draw and name all the isomers of C6H14

Structural isomers in alkenes Draw and name the isomers of C4H8

Draw and name the straight chain isomers of C6H12

Classes of compounds Primary, secondary, tertiary To how many carbons is the carbon attached to the functional group attached Ethanol Propan-2-ol 2-methylpropan-2-ol

Trends in physical properties Volatility (how easily evaporated) Smaller less sticky Branched less sticky Animation 1 Functional polar groups more sticky less volatile alkane>halogenoalkane >aldehyde >ketone >alcohol >acid

Solubility in water More polar more soluble Alcohol, aldehyde, ketone and acid are all soluble

Which compound has the lowest boiling point? CH3CH2CH(CH3)CH3 (CH3)4C CH3CH2CH2CH2CH3 CH3CH2OCH2CH3 Do questions 8 and 9 Do questions 5-8 page 382 for HW

10:2 Alkanes CnH2n+2 Saturated Hydrocarbons Strong bonds – low reactivity However, they burn easily forming CO2 and H2O If not enough O2 they form CO or C (soot)

Show the equation for burning octane

Halogenation of alkanes page 384 in your book UV light and Cl2 yields 2 Cl. Radicals Called homolytic fission

Propagation or chain reaction Show termination step Do this all with molecular models

Do question set 1 for homework Ready for a quiz???

10:3 Alkenes Unsaturated hydrocarbons = bond has a weak pi( )bond along with the sigma (σ)

Addition reactions Ni catalyst and H2 Used in margarine to make saturated fats with higher melting points

Reaction with halogens Propene with Br2 (test for a = bond)

Hydrogen halides Produce halogenoalkanes Propene with HCl HI weaker bonds more reactive than HBr then HCl

Reaction with water Called hydration Alkene to alcohol Use conc. H2SO4 as a catalyst and steam Ethene to ethanol (industrial use to get alcohol)

polymerization Polyethylene Monomer is Polymer is

Polyvinylchloride (PVC)

Teflon (polytetrafluoroethene) what is the starting material? Do questions 10-12

10:4 alcohols CnH2n+1OH Nomenclature handout alcohols -OH (hydroxyl group) functional group Shorter chains soluble in water

combustion Like alkanes Equation for burning of ethanol Longer chains give off more energy

oxidation Alcohols with orange K2Cr2O7 reduce it to green Cr2O3 (breathalyzer test) Primary alcohols oxidize to aldehyde then to acids Ethanol with K2CrO7 Distill to get ethanal (apple smell)

Reflux to get acid Lab activity distillation and refluxing

Secondary alcohols make ketones Propan-2-ol (reflux)

Tertiary alcohols do not readily oxidize Do questions 13-14 Do question set 2 for homework

10:5 Halogenoalkanes CnH2n+1X X = halogen Used as intermediaries in other reactions Polar Cδ+ - Clδ- C e- deficient Nucleophiles e- rich lone pairs attack the e- deficient area SN substitution nucleophile reactions

Examples of nucleophiles H2O OH- NH3 CN- SN2 (bimolecular) primary halogenoalkanes

SN1 tertiary halogenoalkanes Unimolecular Secondary halogenoalkanes can undergo either

Go to page 395 and draw the 2 mechanisms showing curly arrows Animation Do questions 15-17

10:6 Reaction pathways see page 406 in the textbook fill in the reagents and conditions needed Convert 1-chlorobutane into butanoic acid

Do proponal from 1-bromopropane

1,2,3 trichlorpropane from propene

Esters Formed when organic acids react with alcohols Fragrances and flavors RCOOR‘

Draw methyl methanoate from methanol and ethanoic acid

Ester from methanoic acid and propanol Name and draw the structure Nomenclature handout esters Do question 7 Ester lab

Do questions 18-20 Do questions 1-4,6-9,11 pages 416 and 417 in your textbook Do the SL questions (1-11) in your study guide on page 74 Homework question set 3 Quiz 10:3-6