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The Chemistry of Life: Organic and Biological Chemistry BLB 11 th Chapter 25.

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Presentation on theme: "The Chemistry of Life: Organic and Biological Chemistry BLB 11 th Chapter 25."— Presentation transcript:

1 The Chemistry of Life: Organic and Biological Chemistry BLB 11 th Chapter 25

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3 25.1 General Characteristics Structure Structure –Carbon atoms form 4 bonds. –Backbone consists of –C—C— chains or rings. –C—H bond is nearly nonpolar. Stabilities Stabilities –C forms strong bonds with other elements. –Alkanes are stable (unreactive). –Functional groups (sect. 5) change reactivity.

4 General Characteristics Solubility and acid-base properties Solubility and acid-base properties –Hydrocarbons: nonpolar, neutral soluble in water? ______ –C—H (hydrocarbons) plus functional groups…  -C—O—H polar, slightly acidic (alcohols)  -C—O—O—H acidic (carboxylic acids)  -C—N—R 3 basic (amines) –Surfactants combine both properties

5 25.2 Hydrocarbons Compounds containing only C and H Compounds containing only C and H Types: Types: –Alkanes (saturated) – single C–C bonds –Alkenes (unsaturated) – double C=C bonds –Alkynes (unsaturated) – triple C ≡ C bonds –Aromatic – alternating single and double bonds

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7 25.3 Alkanes (C n H 2n+2 ) Variations Variations –Unbranched (normal, “straight-chained”) –Branched –Cyclic (C n H n ) Structural isomers – same number and type of atoms but different bonding arrangements Structural isomers – same number and type of atoms but different bonding arrangements

8 3-D Arrangement Tetrahedral geometry

9 NameFormulaMM m.p. (°C) b.p. (°C) # isomers methane CH ethane C2H6C2H6C2H6C2H propane C3H8C3H8C3H8C3H butane C 4 H pentane C 5 H hexane C 6 H heptane C 7 H octane C 8 H nonane C 9 H decane C 10 H

10 Butane Isomers

11 Pentane Isomers

12 Nomenclature 1. Identify longest C chain → base name 2. Number C atoms – lowest number nearest substituent (branch) 3. Give position and name substituents. 4. More than one substituent? Alphabetical Alphabetical Prefixes Prefixes Some substituents have common names (Table 25.2, p. 1059) Some substituents have common names (Table 25.2, p. 1059)

13 Structure & Nomenclature Examples

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16 Cycloalkanes (C n H 2n ) most stablestablestrained & unstable structure

17 Alkenes & Alkynes Alkenes: C=C double bonds Alkenes: C=C double bonds –Named similarly with an –ene ending and give position of double bond –More reactive than alkanes –Different arrangements of substituents may result in geometric isomers. Geometric isomers – same atoms, same bonds, but different spatial arrangement of substituent groups. Geometric isomers – same atoms, same bonds, but different spatial arrangement of substituent groups. –cis- and trans-

18 Geometric isomers Structural isomers

19 Structure & Nomenclature Examples

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21 Alkenes & Alkynes Alkynes: C C triple bonds Alkynes: C C triple bonds –Named similarly with an –yne ending and give position of triple bond –More reactive than alkenes

22 Aromatic Hydrocarbons Cyclic unsaturated hydrocarbons with alternating single and double C=C bonds. Cyclic unsaturated hydrocarbons with alternating single and double C=C bonds. Ring system often has common name. Ring system often has common name. Less reactive than alkenes or alkynes Less reactive than alkenes or alkynes

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24 Bonding in Benzene

25 25.4 Organic Functional Groups Site of reactivity Site of reactivity R, R', R" represent the alkyl (hydrocarbon) group(s) to which functional group is attached. R, R', R" represent the alkyl (hydrocarbon) group(s) to which functional group is attached.

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28 Functional Group examples Aspartame

29 Functional Group examples

30 25.5 Chirality Chiral compounds – compounds containing carbon atoms with four different attached groups Chiral compounds – compounds containing carbon atoms with four different attached groups –Examples: CHFClBr, CH 3 —C—CH 2 CH 2 CH 3 Enantiomers – nonsuperimposable mirror images Enantiomers – nonsuperimposable mirror images Br H

31 Enantiomers

32 Enantiomers

33 Chiral Compounds D- sugars are preferred D- sugars are preferred L- amino acids are preferred L- amino acids are preferred Drugs Drugs –Ibuprofen: one effective, other inactive –Naproxen: one effective, other toxic


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