Chemistry 1b
Sarah Reisman
301B Schlinger Laboratory
x6044
reisman@caltech.edu
Jim Heath
16A Noyes Laboratory
x6079
heath@caltech.edu
course website: http://chem1.che.caltech.edu/
General Topics:
Introduction to Organic Chemistry
Introduction to Spectroscopy
Ideal and Real Gases
Thermochemistry
Equilibria
Kinetics
this is no ordinary chemistry course:
there is no text book out there that
replaces coming to class!
Chemistry 1b
Wk 1
Monday
3
SR
Molecular Structure,
Intro to Organic
Compounds
RC: Ch. 2-3
Wk 2
10
Tuesday
4
SR
Wed
5
Conjugate, Aromaticity,
Functional Groups
RC: Ch 4.1-4.3, Ch. 7,
Ch. 21.3, 21.9
JH 1 1
Spectroscopy In t r o
JH
12
Spectroscopy: Rotation
Thursday
6
Friday
SR 7
Isomers, Dipoles, Polar
Interactions
OGC: Ch. 3.7, 3.9
RC: Ch. 5, Ch. 19.1-19.5
PS1 due
13
14
JH
PS2 due
Spectroscopy: Vibe
References for entire week of spectroscopy:
OGC: 4.5-4.7; 20.1-20.3; Gray 4.8; P:10.2-10.4; RC: 9-4 to 9-7; 9-9
Wk 3
Wk 4
Wk 5
17
18
MLK Day
(no class )
Spectroscopy (NMR)
OGC: 20.4
RC: 9-10; P: 10.5
Spectroscopy (Mass
Spec); RC: 9-11; P:10.1
25
27
24
JH
JH 1 9
Ideal & Real Gases
OGC: 9.3-9.4; 9.7
Quiz 1 Due (8PM)
31
1
JH
nd
JH
Irreversible/ Reversible
Processes OGC 13.4
2 Law of Thermo
Entropy
OGC: 13.1- 1 3 . 3
7
8
No lecture
Midterm due 8 P M
Chemical Equilib
OGC: 14.1-14.7
14
15
JH
2 1 Last day
to add; Quiz 1
out (4 P M )
PS3 due
JH 2 6
Kinetic Theory
OGC: 9.1-9.2; 9.5-9. 6
20
st
JH
2
3
28
PS4 due
1 Law of Thermo,
Thermochemistry
OGC: Chapter 1 2
JH
4
Spontaneous Processes &
Thermo Equilib OGC:
13.5-13.7 midterm out
10PM
Wk 6
Wk 7
Wk 8
JH
JH
9
SR
Kinetics
OGC: Chapter 1 8
Intro to Organic
Reactions, Arrow
Pushin g
21
22
President’s Day
(no class )
Acidity and Basicity in
Organic Reactions
P: 1.7
28
SR 1
Nucleophilic Subs. at
the Carbonyl
P: Ch.8.9, RC: Ch. 16.1,
16.4, 18.3
16
17
SR 2 3
24
SR 1 8
3
PS6 due
Quiz 2 out (4
PM)
SR 2 5
Organometallic Addition to
the Carbonyl
RC: Ch. 14.9-14.11
P: p. 127-8
SR 2
11
PS5 due
Nucleophiles,
Electrophiles, and the
Carbonyl
RC: 16.1, 16.2, P: Ch. 4 ,
Acetals
SR 8
JH
Equilibrium
Quiz 2 Due (8P M )
Wk 9
10
PS7 due
SR 4
Imines and Enamines
PS8 due
Wk
10
7
9
10
11
Biopolymers, Amide
Bond formation
RC: Ch. 25
Chem. and
Applications of
Polymers RC: Ch. 2 9
PS9
du e
Study Period
Final Exam
Ou t
Wk
11
1 4 Last day to
15
16
17
18
submit late work
(4PM)
SR
Final Du e
Carbons form bonds through sp3, sp2, and sp hybridized orbitals
(remember Ch1a)
methane (CH4)
• tetrahedral carbon
• sp3 hybridized
• σC-H bond
ethane (C2H6)
• C–C single bond, σC-C bond
• generic name: alkane
• alkanes have free rotation around C–C and C–H bonds
for a refresher on chemical bonding and molecular structure, read Chapter 3 of OGC and Chapter 6 of RC
Conformations of Alkanes
conformational isomers: two isomers of a molecule which differ only in the spatial
arrangement of the atoms; conformations are intercovertible by rotation about single bonds.
ethane has 2 conformations:
+ 3.0
kcal/mol
energy
0
60
180
dihedral angle
300
180
dihedral angle
300
butane has 4 conformations:
+ 5.1
kcal/mol
energy
0
for a refresher on chemical bonding and molecular structure, read Chapter 3 of OGC and Chapter 6 of RC
60
Carbons form bonds through sp3, sp2, and sp hybridized orbitals
(remember Ch1a)
ethylene (ethene, C2H4)
• planar
• sp2 hybridized
• one σ bond, one π bond
• rotation around C–C bond is restricted
• generic name: alkene
for a refresher on chemical bonding and molecular structure, read Chapter 3 of OGC and Chapter 6 of RC
Carbons form bonds through sp3, sp2, and sp hybridized orbitals
(remember Ch1a)
acetylene (ethyne, C2H2)
• linear
• sp hybridized
• one σ bond, two π bonds
• generic name: alkyne
key trends:
• bond length:
• C–H acidity:
• reactivity:
for a refresher on chemical bonding and molecular structure, read Chapter 3 of OGC and Chapter 6 of RC
Representing Molecular Structures
Chemists have many different ways of representing the same structure.
Naming Organic Compounds: Hydrocarbons
saturated hydrocarbons: alkanes consisting of carbon and hydrogen.
• generic formula: CnH2n+2
• prefix indicates number of carbons in longest chain
• referred to as “normal” alkanes, e.g. n-hexane
branched alkanes:
# carbons
1
2
3
4
5
6
7
8
9
10
20
n-alkane
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
C7H16
C8H18
C9H20
C10H22
C20H44
name
methane
ethane
propane
butane
pentane
hexane
heptane
octane
nonane
decane
eicosane
substituent
name
methyl
ethyl
propyl
butyl
pentyl
hexyl
heptyl
octyl
nonyl
decyl
eicosyl
Constitutional Isomers: molecules with the same molecular formula but different connectivity of
atoms
• term first proposed by J.J. Berzelius in 1832 to describe compounds with the same composition but different
physical properties
For more info, see RC, Ch 3 or http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/nomen1.htm
Naming Branched Alkanes
identify the parent hydrocarbon (the longest straight chain)
• number the carbons of the parent hydrocarbon, minimizing the sum of the substituent #’s
• the fragments are listed in alphabetical order
• for detailed IUPAC rules, see: http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/nomen1.htm
CH3
CH3
CH3
H3C
name me!
H3C
CH3
H2C
name me!
CH3
CH3
CH3
common alkyl substituents:
H3C
H3C
H3C
CH3
iso-propyl
(i-Pr)
H3C
H3C
sec-butyl
(s-Bu)
H3C
CH3
CH3
iso-butyl
tert-butyl
(i-Bu)
(t-Bu)
For more info, see RC, Ch 3
Cycloalkanes
cycloalkanes: add “–cyclo” prefix
cyclopropane
cyclobutane
cyclopentane
don’t be misled: except for cyclopropane, cycloalkanes are not planar!
• cycloalkanes adopt conformations that:
– provide bond angles closer to 109.5°
– avoid eclipsing interactions
cyclohexane
for more info, see RC, Ch 12
Small Rings Experience “Ring Strain”
• distortion from ideal bond
angles results in “ring strain”
Heat of
Combustion
(kcal/mol)
cyclopropane
cyclobutane
cyclopentane
cyclohexane
cycloheptane
open-chain alkane
499.9
655.9
793.4
944.8
1108.1
don’t be misled: except for cyclopropane, cycloalkanes are not planar!
• cycloalkanes adopt conformations that:
– provide bond angles closer to 109.5°
– avoid eclipsing interactions
Heat of
Combustion per
CH2 (kcal/mol)
166.6
164.0
158.7
157.5
158.4
157.4
total strain
(kcal/mol)
27.7
26.3
6.4
0.4
6.3
for more info, see RC, Ch 12
Unsaturated Hydrocarbons: Alkenes and Alkynes
naming alkenes:
• prefix indicates number of carbons in longest chain, suffix is “–ene”
• number indicates location of double bond
• alkene geometry defined as E (trans) or Z (cis)
Alkene isomers: molecules with the same molecular formula and same connectivity of atoms, which
differ only in alkene geometry
naming alkynes:
• prefix indicates number of carbons in longest chain, suffix is “–yne”
• number indicates location of triple bond