EXPERIMENT #3 MOLECULAR MODELING PART I Prelab Assignment (1) Tabulate the bond angles and carbon-carbon bond lengths for methane, ethane, ethylene, and acetylene. Bond angles
C-C bond length
Methane:
109.5o
–
Ethane:
~109.5o (H-C-H = 109.3o) (H-C-C = 111.0o)
1.54 Å
Ethylene:
~120o
1.33 Å
Acetylene:
180o
1.20 Å
(2) Write the structures of 1-pentanol, 2-pentanol, 2-methyl-1-butanol, and 2-methyl2-butanol. Record their boiling points. Show the direction of the bond dipole in two of the most polar bonds in each molecule.
H
H O
O
1-pentanol b.p. 137-139o C
2-pentanol b.p. 118-119oC
H O
H O
2-methyl-1-butanol b.p. 130oC
2-methyl-2-butanol b.p. 102oC
Provide a specific structure for each of the following types of organic compounds. Keep it simple – you will be building these molecules in lab. (3)
(a) alkyl halide (b) aldehyde (c) ketone (d) amine (e) ether (f) nitrile (g) thiol (h) carboxylic acid (i) ester (j) amide Note: Unlike the generic structures below, your answers should have specific structures and no “R” groups: a) alkyl halide R
b) aldehyde
c) ketone O
O
X
where X = F, Cl, Br, I
R
R
H
d) amine
R
e) ether
H
R
R O
or
N R
H
or
N R
R
N
H
R
R
g) thiol
f) nitrile
R
h) carboxylic acid S
R
C
N
R
O H H
i) ester
R
j) amide O
O
O
O
O
or
R R
O
R
NH2
or R
NHR
R
NR2
(4) Write the structures of the methyl-, ethyl-, isopropyl-, tert-butyl-, and neopentyl bromides.
Br H3C
Br
methyl bromide
Br
ethyl bromide
Br
tert-butyl bromide
isopropyl bromide
Br
neopentyl bromide
