BLOCK ONE Flashcards
a single bond is made of a
sigma bond
a double bond is made of
one sigma bond and one pi bond
a triple bond is made of
one sigma bond and two pi bonds
what does not appear in the DBE formula
oxygen
what are constitutional isomers
have the same molecular formula, different atom to atom bonding sequence
what are conformational isomers
have the same molecular formula, same atom to atom bonding sequence but the arrangement in space differs and it can interconvert by rotation about a single bond
what happens to groups in ring flip
all axial groups»_space;> equatorial
all equatorial groups»_space;> axial
but up stays up and down stays down
the favoured conformer has the largest atom/group in the
equatorial position
what are configurational isomers
same molecular formula, same atom to atom bonding sequence but the arrangement in space differs and they can only be converted by breaking and reforming a covalent bond
what are the two classes of configurational isomers
enantiomers and diastereomers
what are enantiomers
chiral and non-superimposable mirror images
what are diastereomers
chiral, non-superimposable and not mirror images (e/z, cis/trans etc)
state increasing priority of main elements
H < C < N < O < F < Cl < Br < I
if two higher priority on the same side of the double bond, what configuration?
Z
if two higher priority on opposite sides of the double bond, what configuration?
E
when can enantiomers exist?
when you have sp3 carbon with 4 different groups attached
what is an achiral molecule
doesn’t have a carbon with four different groups attached
how can you differentiate between the two enantiomers?
through the direction in which they rotate plane polarised light
what is a racemic mixture
a mixture of equal amounts of the two enantiomers
how do racemic mixtures rotate light
equally in both directions and thus show an overall rotation of zero
is clockwise R or S
R
is anticlockwise R or S
S
if a molecule has high polarity it is
more water-soluble and is hydrophilic
if a molecule has low polarity it is
more lipid-soluble and lipophilic
electron-rich are…
nucleophiles
electron-deficient are…
electrophiles
nucelophiles have…
neutral lone pairs, negative charge, pi bonds or negative atom of polar bond
electrophiles have…
positive charge or positive atom of polar bond
difference between SN1 and SN2
SN1 = bond breaking and then bond forming SN2 = bond breaking/forming is simultaneous
