Ch 9 Meeting 13 slides

Ch 9 Meeting 13 slides - Meeting 13 – Chapter 9...

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Unformatted text preview: Meeting 13 – Chapter 9 Unsaturated hydrocarbons But first a word about organic chemistry • Common elements in organic compounds: • H, C, N, O, F, P, S, Cl, Br (upper right of periodic table) • Carbon forms untold numbers of compounds. Why? • Carbon has many different bonding possibilities. • Carbon forms rings, chains and numerous isomers. • • Functional groups increase the number and diversity of organic compounds 1 • Chapter 2 covered alkanes, CnH2n+2 • Here we examine compounds with double bonds (alkenes) and compounds with triple bonds (alkynes) 2 Alkenes Name based on alkane H2C=CH2 ethene (ethylene) H2C=CHCH3 propene H2C=CHCH2CH3 1‐butene …H2C=CH(CH2)7CH3 1‐decene • Double bond are stronger than single bonds, but weaker than 2 single bonds. Position of Double Bond Name the compound below 3 More than 1 double bond, use diene, triene, tetraene Put the number of the bond in front of the “ene” If the double bond isn’t at the end, number bonds starting as close to the double bond as possible. Example: Alkynes • Compounds containing Carbon‐Carbon triple bonds are alkynes • Rules for naming similar to those for alkenes • HC≡CH ethyne (acetylene) • HC≡CCH3 propyne • …HC≡C(CH2)7CH3 1‐decyne 4 Nomenclature interlude • Positions of functional groups • General Rules for naming organic compounds • Find longest chain (chain must contain most important functional group) Carboxylic acid > anhydrides > esters > amides > nitriles > aldehydes > ketone > alcohols > amines > ethers > alkynes > alkenes Number carbons from the end closest to the functional group. • Find and name groups attached to main chain. 5 Example Methyl = CH3; Ethyl = CH2CH3 = C2H5 Propyl = CH2CH2CH3 = C3H7; Chloro = Cl Example CH3 H3C H C CH CH H2C CH3 H3C CH3 H 3C HC Cl H2C CH3 H3C HC CH H2C CH2 Cl HC CH H2 C C O CH3 7 Cl 2 Cl CH CH H2 C C O CH2 OH 8 H3C H C Cl C H 6 CH 5 C H 4 H2 C 1 OH CH 3 C O Propyl Ethyl Methyl Chloro OH H2C CH3 H2C CH2 H3C Cl H2C 8 4,7-dichloro-5-ethyl-6methyl-3-propyl-octanoic acid 6 Reactivity of alkenes and alkynes Addition to the double bond: hydrogenation Reduction of ethene to ethane: Reduction of acetylene to ethylene to ethane The reduction is difficult to stop at step 1, but it can be done with care. More often, acetylene reacts with 2 moles of H2 to yield ethane. 7 Polymers Polymers are compounds in which many identical molecules have been joined together Nylon Chapter 9: Chemical Bonds EOS 41 The polymer above is polyethylene; the text file I snarfed it from has it mislabeled as nylon. Otherwise all is OK. 8 Polymers have repeating units: the repeating unit in polyethylene is The reactant (monomer) used to form the polymer is ethylene: Polymers such as polyethylene are called addition polymers because their chains are formed by the addition of monomers 9 More addition polymers and their uses Biological Polymers Proteins are biological polymers formed from amino acids, which are molecules that contain both amine (NH2–) and carboxylic acid (–COOH) functional groups. 10 Examples of amino acids. Formation of a polypeptide by condensation polymerization 11 Condensation reaction: two molecules (amino acids. For example) make a larger molecule (dipeptide) and a smaller molecule such as water. Note that the dipeptides can undergo additional condensation reactions to form long‐chain molecules, many of which are proteins. 12 There are several types of biopolymers as shown below 13 HOH2C CH HO HC CH HO CH OH O CH OH Biopolymers Sugars, starches HO CH HO HO CH 2 O HC HC O CHHC OH O HC CHHC OH OH OH CHHC Carbohydrates R H 2N C H O C OH H 2N R C H O C NH R' O C H C OH OH Amino acids Proteins and peptides H 3C H2 C H2 C O C Cn H2 C O O CH2 CH CH2OH H2 C H 3C fatty acid O C Cn H2 OH + CH2OH CHOH CH2OH glycerol H3C CnO + H2 Fats and oils . 14 ...
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