Hydrocarbon
compound composed of only C and H
saturated hydrocarbon
single bonds only (ex: alkane)
unsaturated hydrocarbon
contains double or triple bonds (alkenes, alkynes, arenas)
line structure formula
- carbon atoms @ each corner
- draw bonds between corners
- don’t show H’s on Carbons
- show other atoms
Constitutional Isomers
compounds with same molecular formula, but different connectivity of atoms
how to determine if compounds are constitutional isomers
- write the molecular formula for each
- Find the longest carbon chain
- # each chain from the end nearest the first branch
- compare chain lengths + the identity and location of branches
nomenclature and IUPAC
Parent name: longest carbon chain
substituent: group bonded to parent
IUPAC nomenclature rules
- identify the longest carbon chain parent)
- # the chain to give the substituent the lower
- identical substituents: lower # to the first substituent (# of times substituent occurs - give prefix di, tri, tetra, penta, hexa, etc)
- different substituents & numbering gives a ties:lower number based on alphabetical order (prefixes are not included in alphabetizing)
- multiple parent chains of identical length: number the one with greater substituents
infix
nature of C-C bond (single, double, triple)
torsional strain
strain that arises when going from one conformation to another
anti conformation
groups on adjacent carbons are 180 degree dihedral angle
gauche conformation
groups on adjacent carbons are at a 60 degree dihedral angle
causes of torsional strain
- angle strain: bond angle is smaller or larger than optimal value
- steric strain: (non bonded interaction strain) forcing non bonded atoms close to each other
general formula for cycloalkanes
C(n)H(2n)
naming rules for cycloalkanes
- add prefix cycle
- if one substituent, no #
- if two substituents, # alphabetically
- if three + substituents, lowers set of numbers then alphabetically
bicycloalkanes
two rings that share two carbons
strain
measure of energy stored in a compound due to structural distortion
conformation
any 3D arrangement of atoms in a molecule that results from a rotation about a single bond
dihedral angle
angle created by two intersecting planes, as defined by 3 atoms
small ring strain
exists for rings <6 carbons
stereoisomers
compounds that have the same molecular formula, connectivity of atoms, but different orientation of atoms in space
cis
same side
trans
opposite sides
dispersion forces
weak intermolecular forces of attraction resulting from the interaction between temporary induced dipoles
increase: melting and boiling point increase
