| Terms |
Definitions |
|
observed rotation
|
the number of degrees through which a compound rotates the plane of polarized light
|
|
collecting and drying
|
collect crystals by vacuum filtration using a Buchner funnel, rinse crystals in _cold_ solvent, continue suction until crystals are nearly dry, (options)a. air dry b. drying oven c. dry under vacuum
|
|
guildlines for predicting polarity and solubility
|
all hydrocarbons are nonpolar; compounds with O or N are polar; compounds with halogen atoms are only slightly polar; adding carbon atoms decreases polarity; compounds with four or fewer carbons plus O or N are soluble in water; hydrogen bonding increases solubility; branching lowers intermolecular forces between molecules, increasing solubility in water; organic compounds that belong to the same family are soluble (except when size is very different); the higher the melting point, the less soluble the compound
|
|
-NH2
|
Amine
|
|
difference between solubility and miscibility
|
there can be different degrees of solubility, while miscibility does not have any degree.
|
|
CH3CH3
|
Ethane
|
|
torsional strain (eclipsed-interaction strain)
|
strain that arises when nonbonded atoms separated by three bonds are forced from a staggered conformation to an eclipsed conformation.
|
|
ketone
|
contains an internal C=O group
|
|
angle strain
|
the strain that arises when a bond angle is either compressed or expanded compared to its optimal value
|
|
-COOH
|
Carboxylic Acid
|
|
absolute configuration
|
which of the two possible isomers an enantiomer is (i.e., whether it is the right- or left-handed isomer)
|
|
-O-
|
Ether
|
|
carboxylic acid
|
contains a terminal O=C-OH group
|
|
diastereomers
|
stereoisomers that are not mirror images of each other; refers to relationships among two or more objects
|
|
atropisomers
|
enantiomers that lack a chiral center and differ because of hindered rotation
|
|
-COH
|
Aldehyde
|
|
-OH
|
Alcohol
|
|
constitutional isomers
|
have the same molecular formula but a different connectivity of atoms in their molecules
|
|
dissolving the solvent
|
find a solvent with steep solubility vs temp curve, heat solvent to boiling point, dissolve solid in minimum of boiling solvent in flask, if needed add decolorizing charcoal
|
|
miscible
|
two liquids that are miscible will mix homogeneously (one phase) in all proportions.
|
|
crystallizing
|
allow the solution to cool, (if crystals appear) cool mixture in ice water bath, (if no crystals appear) scratch the flask with a glass rod, seed the solution with origional solid, cool the solution in ice water bath, evaporate excess solvent and allow solution to cool again
|
|
levorotatory
|
refers to a substance that rotates the plane of polarized light to the left
|
|
-CO2-
|
Ester
|
|
specific rotation
|
observed rotation of the plane of polarized light when a sample is placed in a tube 1.0dm in length and at a concentration of 1g/ml.
|
|
configuration
|
refers to the arrangement of atoms about a stereocenter
|
|
resolution
|
separation of a racemic mixture into its enantiomers
|
|
CH3(CH2)8CH3
|
Decane
|
|
chiral
|
an object that is not superposable on its mirror image
|
|
equatorial bond
|
a bond that lies roughly along the equator of the ring
|
|
CH4
|
Methane
|
|
amine
|
contains a terminal NH2 group
|
|
alkene
|
consists of at least one carbon to carbon double bond
|
|
CH3(CH2)6CH3
|
Octane
|
|
alcohol
|
contains an -OH group
|
|
CH3CH2CH3
|
Propane
|
|
CH3(CH2)3CH3
|
Pentane
|
|
bicycloalkane
|
an alkane containing two rings that share two carbons
|
|
dextrorotatory
|
refers to a substance that rotates the plane of polarized light to the right
|
|
how to remove insoluble impurities
|
decantation (if particles are large), fluted filter (more than 10ml), or filtering pipet (less than 10ml)
|
|
chiral center
|
a tetrahedral atom, most commonly carbon, that is bounded to four different groups; one type of stereocenter
|
|
alkane
|
consists of only carbon to carbon single bonds
|
|
configurational isomers
|
isomers that differ by the configuration of substituents on an atom
|
|
ether
|
contains an internal O-O group
|
|
strain
|
an instability within a structure associated with higher internal energy
|
|
CH3(CH2)2CH3
|
Butane
|
|
chromatography
|
a separation method involving passing a vapor or solution mixture through a column packed with a material with different affinities for different components of the mixture
|
|
steric strain
|
the strain that arises when nonbonded atoms separated by four or more bonds are forced closer to each other than their atomic radii would allow; also called nonbonded interaction strain, or van der Waals strain
|
|
mother liquor
|
the solution that remains after a crystallization
|
|
aldehyde
|
contains a terminal O=C-H group
|
|
enantiomer
|
stereoisomers that are nonsuperposable mirror images of each other; refers to a relationship between pairs of objects
|
|
opical purity
|
the specific rotation of a mixture of enantiomers divided by the specific rotation of the enantiomerically pure substance (expressed as a percent). Optical purity is numerically equal to enantiomeric excess, but experimentally determined.
|
|
isomer
|
different molecules with the same molecular formula
|
|
R
|
from the Latin, rectus; used in the R,S convention to show that the order of priority of groups on a chiral center is clockwise
|
|
CH3(CH2)7CH3
|
Nonane
|
|
CH3(CH2)4CH3
|
Hexane
|
|
stereocenter
|
an atom about which exchange of two groups produces a stereoisomer; chiral centers are one type of this
|
|
-CONH-
|
Amide
|
|
CH3(CH2)5CH3
|
Heptane
|
|
plane of symmetry
|
imaginary plane passing through an object dividing it so that one half is the mirror image of the other half
|
|
axial bond
|
a bond to a chair conformation of cyclohexane that extends for the ring parallel to the imaginary axis through the center of the ring; a bond that lies roughly perpendicular to the equator of the ring
|
|
twist-boat conformation
|
a nonplanar conformation of a cyclohexane ring that is twisted form and slightly more stable than a boat conformation
|
|
conformational isomers (conformers)
|
the different conformations of a molecule as it rotates around a bond (staggered, eclipsed)
|
|
Fischer projection
|
a 2-D projection of a molecule; in these projections, groups on the right and left are by convention in front, while those at the top and bottom are to the rear.
|
|
stereoisomers
|
have the same molecular formula and the same connectivity but different orientations of their atoms in space
|
|
solubility test
|
40mg of solute added to 1 mL of solvent
|
|
diaxial interactions
|
refers to the steric strain arising from interaction between an axial substituent and an axial hydrogen on the same side of a chair conformation of a cyclohexane ring
|
|
ester
|
contains an internal O=C-O- group
|
|
four steps of macroscale crystallization
|
dissolving the solid; removing insoluble impurities; crystallization; collecting and drying
|
|
Craig tube advantage
|
in microscale crystallization, minimizes the number of transfers of solid material, thus resultign in a greater yield of crystals; also, separation of crystals from mother liquor is very efficent, and little time is required for drying crystals
|
|
alkyne
|
consists of at least one carbon to carbon triple bond
|
|
meso compound
|
an achiral compound possessing two or more chiral centers that also has chiral isomers
|
|
S
|
From the Latin, sinister; used in the R,S convention to show that the order of priority of groups on a chiral center is counterclockwise
|
|
racemic mixture
|
a mixture of equal amounts of two enantiomers
|
|
polarimeter
|
an instrument for measuring the ability of a compound to rotate the plane of polarized light
|
|
-CO-
|
Ketone
|
|
enantiomeric excess (ee)
|
the difference between the percentage of two enantiomers in a mixture
|
|
center of symmetry
|
a point so located that identical components of an object are located on opposite sides adn equidistant from that point along any axis passing through it
|
