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111 terms

Orgo Lecture 1

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alkane
carbon-carbon single bond or methane
alkene
carbon-carbon double bond
alkyne
carbon-carbon triple bond
alcohol
R-OH
ether
R-O-R
amine
aldehyde
ketone
carboxylic acid
ester
amide
the R" and R' can be H
alkyl
an alkyl group is an alkane missing one hydrogen
gem-dihalide
vic-dihalide
hydroxyl
-OH
alkoxy
-OR
hemiacetal
hemiketal
mesyl group
Ms--
tosyl group
Ts--
carbonyl
acetyl
contains a methyl group single-bonded to a carbonyl
acyl
anhydride
aryl
-Ar, -C6H5
benzyl
hydrazine
hydrazone
vinyl
vinylic
allyl
nitrile
epoxide
enamine
imine
oxime
nitro
nitroso
meth
1
eth
2
prop
3
but
4
pent
5
hex
6
hept
7
oct
8
non
9
dec
10
IUPAC rules for nomenclature
* the longest carbon chain with the most substituents determines the base name
* the end carbon closet to a carbon with a substituent is always the first carbon. in the case of a tie, look to the next substituent
* any substituent is given the same number as its carbon
* if the same substituent is used more than once, use the prefixes di-, tri-, tetra, and so on
* order the substituents alphabetically (ignore prefix)
electrostatic force
force between the electrons and the nuclei that creates all molecular bonds.
coordinate covalent bond
one nucleus can donate both electrons
sigma-bond
when the bonding pair of electrons are localized directly between the two bonding atoms.
pi-bond
additional bonds between two sigma bonded atoms. more reactive. prevent rotation.
sp3 bond angles
109.5 degrees
dsp3
90 degrees, 120 degrees
d2sp3
90
four rules for resonance
1) atoms must not be moved. move electrons
2) number of unpaired electrons must remain constant
3) resonance atoms must lie in the same plane
4) only proper Lewis structures allowed
two conditions must exist for resonance to occur
1) a species must contain an atom either with a p orbital or an unshared pair of electrons
2) that atom must be single bonded to an atom that posses a double or triple bond.
Huckel's rule
planar monocylic rings with 4n+2 pi-electrons) should be aromatic (display resonance)
dipole moment
occurs when the center of positive charge on a molecule does not coincide with the center of negative charge.
μ=qd
induced dipoles
can be induced in an otherwise nonpolar molecule by a polar molecule, ion, or electric field.
instantaneous dipole moment
can exist in an otherwise nonpolar molecule. arise because the electrons in a bond move about the orbital, and at any given moment may not be distributed exactly between the two bonding atoms even when the atoms are identical.
intermolecular attractions
occur solely due to dipole moments. generally about 1% as strong as covalent bonds.
London Dispersion Forces
the weakest dipole-dipole force is between two instantaneous dipoles. weak, but responsible for phase changes
isomers
unique molecules with the same molecular formula
conformational isomers
not true isomers. different spatial orientations of the same molecule
structural isomer
have the same molecular formula, but different bond-to-bond connectivity
chirality
handedness
chiral molecules
molecules that have 'handedness'. differ from reflection.
achiral molecules
exactly the same as their reflections
chiral carbon
when attached to four different substituents
absolute configuration
the only way to physically describe the orientation of atoms around a chiral center.
1) number atoms attached to the chiral center from highest to lowest priority. largest atomic weights are given the highest priority
2) if two atoms have the same element, then their substituents are sequentially compared in order of decreasing priority until one of the substituents is found to have a greater priority than the corresponding substituent on the other carbon.
3) substituents on double and triple bonds are counted two and three times respectively
4) make lowest priority group face away, and see which direction highest to lowest
absolute configuration of R
indicated by a clockwise circle.
absolute configuration of S
indicated by a counterclockwise circle.
relative configuration
not related to absolute configuration. molecules have the same _____ _____ about a carbon if they differ by only one substituent and the other substituents are oriented identically about the carbon. this orientation is inverted in an Sn2 reaction.
observed rotation
the direction and degree to which a compound rotates plane polarized light.
polarimeter
screens out photons with all but one orientation of electric field.
plane-polarized light
the resulting light from a polarimeter consists of photons with their electric fields oriented in the same direction.
optically inactive
no rotation of the plane or electric field by a typical compound. may be compounds with no chiral center
racemic mixture
chiral compounds containing equal amounts of both stereoisomers
optically active compound
rotates plane-polarized light.
rotates light clockwise
designated '+' or 'd'
rotates light counterclockwise
designated '-' or 'l'
observed rotation
the direction and number of degrees that the electric field in plane-polarized light rotates when it passes through a compound is called that compounds ____ ____.
specific rotation
simply a standardized form of observed rotation that is arrived at through calculations using observed rotation and experimental parameters.
enantiomers
have the same molecular formula, have the same bond-to-bond connectivity, are mirror images of each other, but are not the same molecule. must have opposite absolute configurations at each chiral carbon.

rotate plane polarized light in opposite directions

aside from reactions with plane-polarized light and with other chiral compounds, have the same physical and chemical properties.
optical purity
refers to the ratio of actual rotation to the rotation of a pure sample.
enantiomeric purity
the ratio of pure enantiomer to racemic mixture. optical purity equals ___ ____ for any mixture of enantiomers
resolution
the separation of enantiomers
diastereomers
have the same molecular formula, have the same bond-to-bond connectivity, are NOT mirror images to each other, and are not the same compounds.
geometric isomer
exist due to hindered rotation about a bond. rotation may be hindered due to ring structure, double or triple bond. have different physical properties.
cis-isomers
molecules with same side substituents. have dipole moment. stronger intermolecular forces leading to higher boiling points. less symmetry so fewer crystals, thus lower melting points.
trans-isomers
molecules with opposite-side substituents. do not have dipole moment.
steric hindrance
substituent groups in the cis position may crowd each other. produces higher energy levels resulting in higher heats of combustion.
system to describe geometric isomers unambiguously
two substituents on each carbon are prioritized by atomic weight. labeled E or Z.
E (entegen)
higher priority substituents exist on opposite sides
Z (zusammen)
higher priority substituents exist on the same side.
maximum number of optically active isomers in a single compound.
2ⁿ, where n is the number of chiral centers.
meso compounds
two chiral centers in a single molecule may offset each other. have a plane of symmetry through their center which divides them into two halves that are mirror images of each other. achiral and optically inactive.
epimers
diastereomers that differ at only one chiral carbon.
anomers
if a ring closure occurs at the epimeric carbon, two possible diastereomers called ______. distinguished by the orientation of their substituents. α and β.
anomeric carbon
the chiral carbon of an anomer.
Fisher Projections
vertical lines are assumed to be oriented into the page. horizontal lines are assumed to be oriented out of the page.
Newman projection
a view straight down the axis of one of the σ-bond. both the intersecting lines and the large circle are assumed to be carbon atoms.
index of hydrogen deficiency
indicates the number of pairs of hydrogens a compound is required in order to become a saturated alkane.
n-propyl
isopropyl
n-butyl
isobutyl
sec-butyl
tert-butyl