Chapter 5 Flashcards
define a constitutional isomer
a constitutional isomer has the same molecular formula but different constitution
define a stereoisomer
a stereoisomer has the same molecular formula and constitution but different spatial arrangement of atoms
what characterizes a cis stereoisomer?
the identical groups are on the same side of a double bond
what characterizes a trans stereoisomer?
the identical groups are on opposite sides of a double bond
is it cis or trans if two groups are connected at the same spot?
neither.
define chirality center
a chirality center is a tetrahedral carbon with four different groups around it
define enantiometer
an enantiomer is a type of stereoisomer. it is the non-superimpose-able mirror image
S is clockwise or counterclockwise?
counterclockwise
R is clockwise or counterclockwise?
clockwise
how do enantiomers behave with plane-polarized light? melting or boiling?
a pair of enantiomers will have the same physical properties (melting and boiling points), but will rotate plane-polarized light in opposite directions
what is a racemic mixture?
a solution containing equal amounts of both enantiomers in a pair. (net rotation of plane polarized light will be zero.)
define a diastereomer
disastereomers are stereoisomers that are non-superimpose-able and NOT mirror images
how many stereoisomers is it possible for one molecule to have given that it has n chirality centers?
2^n. each chirality center has a enantiomer pair, which can add up to up to 2^n. however, some of the configurations may end up being redundant.
what is rotational symmetry?
for a ring, rotational symmetry is when a molecule looks the same when rotated 180 degrees around an axis of symmetry.
what is reflectional symmetry?
reflectional symmetry is when a molecule looks the same on either side of a plane of symmetry. (or around one point, which is known as inversion.)
what is a meso compound?
a meso compound exhibits reflectional symmetry. (between what you think would be two enantiomers, meaning that they are actually meso, or the same, compounds. this leads to
what do horizontal lines signify in a Fischer projection?
coming out of the page
what do vertical lines signify in a Fischer projection?
going into the page
how do diasteromers behave with plane-polarized light? melting and boiling point?
diastereomers have entirely different properties, including physicals properties (mp & bp) and how they interact with plane-polarized light
what are two ways to separate enantiomers?
column chromotography using a chiral medium/stationary phase & chemically turning them into diastereomers, which can be separated by their physical properties, then turning them back into enantiomers chemicaly
