, molecules
to be called organic, a molecule needs to have C and H
EX. CO2 H2O inorganic
1s elements are not involved in ochem
hybridisation sp3 = tetrahedral = 109.5°
sp2 = trigonal planar = 120°
sp = linear = 180°
bond order n° of covalent bonds shared by 2 atoms (single = bond order 1, double = bond order 2,
etc…)
* the greater the difference in electronegativity between atoms in a bond, the
more ionic the bond gets
more stable versions of molecules
carbon with lowest number is in front
newman projection assumes viewer is looking along the longitudinal axis of a C-C bond
the staggered and eclipsed conformations are two extremes. the staggered
conformer is more stable bc of stabilising interactions between C-H bond
steric strain repulsion between e- clouds of atoms/groups
- increases as size of atoms/groups increases
conformers anti = big groups opposite each gauche = big groups next
other to each other
greater steric strain in gauche bc the substituents are closer, called gauche
interaction
chair conformer completely free of strain, has bond angles of 111°, close to the ideal 109.5°
DIAMS on
Structure and properties of molecules, including stereochemistry
Resonance structures, conjugation and aromaticity
, equatorial (slanted sideways) and axial
bonds (vertical)
if A up, then E down & vice versa
ring flip conversion of cyclohexane between 2 stable chair conformers
- bonds that are equatorial in chair 1 are axial in chair 2
boat conformer free of angle strain, but C-H bonds are eclipsed and flagpole hydrogens make
steric hindrance, so not as stable
twist - boat more stable than boat
as flagpole H have
moved away
half - chair most unstable state
two chair conformers of monosubsituted cyclohexane are NOT equivalent
- the one with substitute in equatorial is more stable as it has more space
around it and thus less steric interactions
axial position means parallel to H, so
not as stable
1,3-diaxial steric interactions between axial substituent located on C1 of cyclohexane & H
interaction (or other substituents) on C3 and C5
cis isomers substituents on same side
geometric isomers, have different spatial
trans isomers substituents on different side arrangements
both cis and trans isomers have 2 chair conformations
both in equatorial is more stable for both isomers
stability: chair > twist-boat > boat > half-chair
most cyclohexanes are chair at any given moment
to be called organic, a molecule needs to have C and H
EX. CO2 H2O inorganic
1s elements are not involved in ochem
hybridisation sp3 = tetrahedral = 109.5°
sp2 = trigonal planar = 120°
sp = linear = 180°
bond order n° of covalent bonds shared by 2 atoms (single = bond order 1, double = bond order 2,
etc…)
* the greater the difference in electronegativity between atoms in a bond, the
more ionic the bond gets
more stable versions of molecules
carbon with lowest number is in front
newman projection assumes viewer is looking along the longitudinal axis of a C-C bond
the staggered and eclipsed conformations are two extremes. the staggered
conformer is more stable bc of stabilising interactions between C-H bond
steric strain repulsion between e- clouds of atoms/groups
- increases as size of atoms/groups increases
conformers anti = big groups opposite each gauche = big groups next
other to each other
greater steric strain in gauche bc the substituents are closer, called gauche
interaction
chair conformer completely free of strain, has bond angles of 111°, close to the ideal 109.5°
DIAMS on
Structure and properties of molecules, including stereochemistry
Resonance structures, conjugation and aromaticity
, equatorial (slanted sideways) and axial
bonds (vertical)
if A up, then E down & vice versa
ring flip conversion of cyclohexane between 2 stable chair conformers
- bonds that are equatorial in chair 1 are axial in chair 2
boat conformer free of angle strain, but C-H bonds are eclipsed and flagpole hydrogens make
steric hindrance, so not as stable
twist - boat more stable than boat
as flagpole H have
moved away
half - chair most unstable state
two chair conformers of monosubsituted cyclohexane are NOT equivalent
- the one with substitute in equatorial is more stable as it has more space
around it and thus less steric interactions
axial position means parallel to H, so
not as stable
1,3-diaxial steric interactions between axial substituent located on C1 of cyclohexane & H
interaction (or other substituents) on C3 and C5
cis isomers substituents on same side
geometric isomers, have different spatial
trans isomers substituents on different side arrangements
both cis and trans isomers have 2 chair conformations
both in equatorial is more stable for both isomers
stability: chair > twist-boat > boat > half-chair
most cyclohexanes are chair at any given moment
