Exam 2 Flashcards
What is a constitutional isomer?
different molecule, same molecular formula
What is a conformational isomer?
different 3-D shape of the same molecule
What is a staggered conformation?
The back atoms are evenly spaced from the front atoms
What is eclipsed conformation?
the back atoms are directly behind the front atoms
Is staggered or eclipsed conformation favored and why?
stagger… lower energy conformation
What is a dihedral angle?
angle in Newman projection between two bonds, one to the front atom and one to the back atom
What is torsional strain?
repulsion between bonds when eclipsed
What is steric strain?
When non-bonded atoms are too close, causes higher energy (depends on size… amount of strain can vary)
What is gauche?
adjacent, large molecules in a staggered conformation
What is anti?
large molecules are opposite each other in staggered conformation
What is syn?
large groups are eclipsed with each other
Where should the largest groups be in order for the molecule to be in its lowest energy conformation?
anti
Where should the largest groups be in order for the molecule to be in its highest energy conformation?
syn
Can cyclic molecules rotate bonds?
no, they would break
What is angle strain?
strain caused by bonds angles being significantly different than what they ideally should be
Which molecule has the butterfly conformation?
cyclobutane
Which cyclic molecule has no angle strain?
cyclopentane
Which cyclic molecule has the envelop conformation?
cyclopentane
What type of strain is present on the envelop conformation?
minimal amount of torsional
What is the conformation of cyclohexane?
chair conformation
What are the two group types present on a chair conformation?
axial and equatorial
What direction does an axial group point?
the direction of the bond its coming from
What direction does an equatorial bond point?
parallel to the C-C bond in front of or behind it
Why is a boat conformation not as favored as the chair conformation?
causes two groups to eclipse so its higher in energy