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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.
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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
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 • Page 370 in your book • Rule #1 Name the longest chain • Build pentane and show how it rotates around a single bond
#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
If a functional group can only be in one place leave off the number • Like propene
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
Structural isomers in alkenes • Draw and name the isomers of C4H8
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)
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
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