Chapter 2 Flashcards
conformations: different … of atoms that result from … about a single bond
spatial arrangements; rotation
staggered conformation: atoms/ groups on adjacent carbons are as
far apart as possible
eclipsed conformation: atoms/groups on adjacent carbons are as
close as possible
compounds reside in … conformational state
lowest E
eclipsed conformation is less stable because of
hyperconjugation
in staggered conformation, highest molecular orbital overlaps with
smallest antibonding molecular orbitals
… conformation: all conformations between staggered and eclipsed
skew
anti conformation is when the groups are … apart
180 degrees
gauche: groups are
60 degrees apart
torsional strain: resistance to …, non-bonded atoms separated by 3 bonds forced from … to …
rotation; staggered; eclipsed
angle strain: bond angle is …/… compared to optimum values
expanded; compressed
steric strain: non-bonded atoms separated by 4+ bonds are
forced closer to each other
strain: a measure of the energy stored in a compound due to a
structural distortion
dihedral angle: the angle created by two …, each defined by … atoms
intersecting planes; three
the energy difference between the conformational extremes arise from the stabilization of the staggered conformation. This arises because of a small … interactinon between a filled C-H bonding MO of one carbon and the empty/unfilled C-H antibonding MO on the adjacent carbon with which it is aligned
donor-acceptor
puckering of the ring alters the strain energy in two ways:
(1) it decreases the … associated with eclipsed interactions but
(2) it increases further the … caused by the compression of C–C–C bond angles
torsional strain; angle strain
a boat conformation is considerably less stable than a chair because of th e… associated with four pairs of eclipsed C-H interactions and the … between the two “flagpole” hydrogens
torsional strain; steric strain
some of the strain in the boat conformation can be relieved by a slight twisting of the ring to a … conformation
twist-boat
as the size of the alkyl substituent increases, the preference for conformations with the group … increases
equatorial
alkanes are … hydrocarbons, containing only C-C …
saturated; single bonds
alkanes are … hydrocarbons because the physical properties of the higher members of this class resemble those of the long C-chain molecules we find in … and …
aliphatic; animal fats; plant oils
a hydrocarbon that contains one or more C-C double bonds, triple bonds, or benzene rings, is classified as an … hydrocarbon
unsaturated
alkane names (based on number of C): C: C2: C3: C4: C5: C6: C7: C8: C9: C10: C11: C12: C13: C14: C15: C16: C17: C18: C19: C20:
methane; ethane; propane; butane; pentane; hexane; heptane; octane; nonane; decane; undecane; dodecane; tridecane; tetradecane; pentadecane; hexadecane; heptadecane; octadecane; nonadecane; eicosane
alkanes have the general molecular formula
CnH2n+2