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.
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
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
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
NameFormulaMM m.p. (°C) b.p. (°C) # isomers methane CH 4 16-183-1611 ethane C2H6C2H6C2H6C2H630-183-891 propane C3H8C3H8C3H8C3H844-187-441 butane C 4 H 10 58-138-0.52 pentane C 5 H 12 72-130363 hexane C 6 H 14 86-95685 heptane C 7 H 16 100-91989 octane C 8 H 18 114-5712518 nonane C 9 H 20 128-5415135 decane C 10 H 22 142-3017575
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)
Cycloalkanes (C n H 2n ) most stablestablestrained & unstable structure
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-
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
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
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.
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