Chemistry The of Life: Organic and Biological Chemistry
BLB 10th Chapter 25
25.1 General Characteristics
Structure
Carbon atoms form 4 bonds. Backbone consists of C--C-- chains or rings. C--H bond is nearly nonpolar.
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
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--R3 basic (amines)
Surfactants combine both properties
25.2 Hydrocarbons
Compounds containing only C and H 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 (CnH2n+2)
Variations
Unbranched (normal, straight-chained) Branched Cyclic
Structural isomers same number and type of atoms but different bonding arrangements
Tetrahedral geometry
3-D Arrangement
Name
Formula
MM
m.p. ( C)
b.p. ( C)
# isomers
methane ethane
propane butane
CH4 C2H6
C3H8 C4H10
16 30
44 58
-183 -183
-187 -138
-161 -89
-44 -0.5
1 1
1 2
pentane hexane
heptane octane
C5H12 C6H14
C7H16 C8H18
72 86
100 114
-130 -95
-91 -57
36 68
98 125
3 5
9 18
nonane decane
C9H20 C10H22
128 142
-54 -30
151 175
35 75
Butane Isomers
Pentane Isomers
Nomenclature
Identify longest C chain base name 2. Number C atoms lowest number nearest substituent 3. Give position and name substituents. 4. More than one substituent?
1.
Alphabetical Prefixes substituents Some have common names (Table 25.2, p. 1071)
Structure & Nomenclature Examples
Structure & Nomenclature Examples
Structure & Nomenclature Examples
Cycloalkanes (CnH2n)
most stable structure
stable structure
strained & unstable
25.4 Alkenes & Alkynes
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.
cis- and trans-
Structural isomers
Geometric isomers
Structure & Nomenclature Examples
Structure & Nomenclature Examples
Alkenes & Alkynes
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. Ring system often has common name. Less reactive than alkenes or alkynes
Bonding in Benzene
25.5 & 25.6 Functional Groups
Site of reactivity R, R', R" represent the alkyl (hydrocarbon) group(s) to which functional group is attached.
Functional Group examples
Aspartame
Functional Group examples
H H NH2 O N CH2 CH CO2H
HO
H
25.7 Chirality
Chiral compounds compounds containing carbons with four different attached groups
Examples: CHFClBr, CH3--C--CH2CH2CH3
Enantiomers nonsuperimposable mirror images
Enantiomers
Enantiomers
Chiral Compounds
D- sugars are preferred L- amino acids are preferred Drugs
Ibuprofen: one effective, other inactive Naproxen: one effective, other toxic