Chapter 3 Flashcards
alkane general formula
CnH2n+2
alkane naming: 1 Carbon
meth-
alkane naming: 2 Carbon
eth-
alkane naming: 3 Carbon
pro-
alkane naming: 4 Carbon
but-
alkane naming: 5 Carbon
pent-
alkane naming: 6 Carbon
hex-
alkane naming: 7 Carbon
hept-
alkane naming: 8 Carbon
oct-
alkane naming: 9 Carbon
non-
alkane naming: 10 Carbon
dec-
alkane naming: 11 Carbon
undec-
alkane naming: 12 Carbon
dodec-
IUPAC Rules
- longest chain is the base name
- number the longest chain beginning by the nearest constituent
- name the groups and give location, write them in alphabetical order
- use commas to separate numbers from numbers, dashes to separate letters from numbers
describe “iso”
a Y structure, split at the end
describe “sec-butyl”
a secondary carbon
describe a “tert-butyl”
a tertiary carbon
naming multiple groups: 2
di-
naming multiple groups: 3
tri-
naming multiple groups: 4
tetra-
naming multiple groups: 5-10
same as alkane naming
cycloalkane general formula
CnH2n
__________ compounds are named by attaching the prefix “cyclo” to the root chain
monocyclic
when naming a cycloalkane, the root is assigned to __________
the greatest number of carbons
when naming a cycloalkane, if there is only 1 substituent, the location can be _____________
omitted
what are bicyclic compounds?
composed of 2 distinct rings attached by one bond
what are bridged compounds?
unique types of bicyclic molecules composed of 3 rings attached by 2 bridgeheads
physical properties of a cycloalkane
- nonpolar
- relatively inert
- boiling and melting point depend on molecular weight
cis (Z)
largest substituents are on the same side
trans (E)
largest substituents on opposite sides
wedge
towards you
dash
away from you
how to determine is it is an isomer or conformer based off of cis and trans?
if double bonds are switching locations (cis becomes trans, trans becomes cis) it is an isomer. if single bonds are rotating (cis is still cis, trans is still trans), that is a conformer.
trend of boiling point of alkanes
as the number of carbons increase, boiling point increases
trend of melting point of alkanes
- melting point increases as the carbon chain increases
- even numbers have higher melting point than odd number alkanes
newman projection
drawings used to help us visualize all conformers that can be made by rotating a sigma bond
newman projection: 0 degrees
eclipsed
newman projection: 60 degrees
gauche
newman projection: 180 degrees
anti
newman projection energy and stability: eclipsed
highest energy, lowest stability
newman projection energy and stability: gauche
middle energy, middle stability
newman projection energy and stability: anti
lowest energy, most stable
conformational energy: CH3/CH3 eclipsed
11 kj/mol
conformational energy: CH3/H eclipsed
6 kj/mol
conformational energy: H/H eclipsed
4 kj/mol
conformational energy: CH3/CH3 gauche
3.8 kj/mol
higher the heat of combustion: ___ energy, ___ stability
higher energy, lower stability
lower the heat of combustion: ___ energy, ___ stability
lower energy, higher stability
straight chains are _______ stable than branches chains
less
angle strain
when cyclic tetrahedral bongs are forced out of their ideal bond angle of 109.5 (the smaller the cycloalkane, the more angle strain)
torsional strain
exists when neighboring carbons possess hydrogens that overlap in space (eclipse)
axial position
vertically parallel to the axis of the ring
equatorial position
outward toward equator
is axial or equatorial more stable?
equatorial
when a chair conformation flips: axial become ______
equatorial
when a chair conformation flips: equatorial become ______
axial