CHEM 106 1nd Edition Lecture 5Outline of Last Lecture I. Naming AlkanesII. Counting and Identifying IsomersIII. Drawing Organic MoleculesIV. Monomers + PolymersOutline of Current Lecture II. RingsIII. Alkenes + AlkynesIV. IsomersV. NomenclatureVI. Aromatic CompoundsCurrent LectureChapter 13: Organic Chemistry (continued)Rings are indicated by cyclo ___ aneEx: Δ cyclopropane ⌂ cyclopentane Molecular formula CnH2n (not Cn H2n+2 of linear alkanes)-rings have 2 less H’s13.3 Alkenes + AlkynesDouble bond (9.5) Fig. 9.34Sp2 hybrid on Cσ + π bonds – all atoms are on a planeDouble bond prevents rotation Fig. 13.12Triple bond: H – C ≡ C – H linear moleculeSp hybrid on C σ + 2π bonds ethylene (acetylene)-position of the double bond is indicated by the lower number of the C involvedEx: 2-pentyne triple bond goes between carbons 2 and 3-start counting from the end that gives you the smaller number-name ene or yne first, then branches-big chains, enes or ynes, then any decorationsReactivityAddition reactions + →Also H2, Br2, I2…Isomers:Nomenclature:Trans – larger substituents are oppositeCis – “same side” larger substituents are on the same sideAlkanes don’t have these (trans/cis isomers) because there is free rotation about their C-C bondsEx: cis-2-pentenePent – 5 carbons ene – double bond 2 – position of bond2- methyl-2-pentene (cis, trans, not defined)Polymers of alkenes: Polyethylene n H2C = CH2 → -(CH2-CH2)-n n = 1,000-1,000,000Variations: high density polyethylene → HDPEMolecular weight 1,000 – 500,000 unbranched chains rigid + strongLow density polyethylene → LDPECopolymer with r = alkyl chainMolecular weight: 10,000-100,000Fig. 13.17TeflonC-F bonds are very strongMonomerPolyvinyl Chloride MonomerPVCPolypropyleneMonomerRope13.4 Aromatic Compounds-have alternating single and double bonds consistentlyStructural isomersMethyl benzene (toluene) Numbering1,2-dimethyl benzene1,3-dimethyl benzene1,4-dimethyl benzenePolycyclic Aromatic Hydrocarbons (PAH)Especially stable compounds, are released by many things (ex: burning plastics)Naphthalene Polymers Styrene C=C has lots of effect on the molecule13.5 Amines (N)R- a group that bonds through a single bondPrimary Amine Secondary Amine-the R’s do not need to be the sameEx: amphetamine (primary)- amines are all basic-all are not cationsReactions:Basicity: R3Ṅ + H2O → R3N+H + OH-(amine formation
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