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55 Cards in this Set
- Front
- Back
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isomers
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compounds with the same number and types of atoms but differing in arrangement
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constitutional isomers
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compounds made of the same stuff but connected differently
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stereoisomers
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compounds whose atoms are connected in the same ways but have different arrangements in space
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enantiomers
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non-superimposable mirror images, differ at all chirality centers across a mirror place (DO R/S)
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diastereomers
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non-superimposable, non-mirror images, differ by one or more chirality centers (DO R/S)
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angle strain
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strain due to the expansion and compression of bond angles, ex. cyclopropane
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torsional strain
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strain due to eclipsing of H-H bonds on neighboring atoms
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steric strain
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strain due to repulsive interactions between atoms when they approach each other too closely (esp large substituents)
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the ideal angle for ring angles is...
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109 degrees (tetrahedral angle)
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the most strained ring is...
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cyclopropane, small and median rings are strained but larger ones aren't
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the least strained ring is...
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cyclohexane, can adopt a strain free chair conformation
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how does cyclobutane reduce strain?
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It has one carbon bent slightly out of the plane which increases angle strain but decreases torsional strain
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how does cyclopentane reduce strain?
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It twists one carbon out of the place to decrease torsional strain while increasing angle strain.
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monosubstituted cyclohexanes
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the energy difference between axial and equitorial conformations is due to 1,3-diaxial interactions... the group at 1 interacts with the hydrogens at C3, and C5, causing steric strain
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disubstituted cyclohexanes
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when you have groups on the axial and equitorial faces, you have to flip the chair conformation to determine the energy differences between the two conformations (GAUCHE)
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a molecule is chiral when...
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it has no symmetry, has chirality centers (four different groups attached to a carbon)
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a molecule is achiral when...
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it has a plane of symmetry
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a mesoform has...
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a plane of symmetry (is achiral) and chirality centers
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levorotatory
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molecules that polarize light to the left/counterclockwise (-)
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dextrorotatory
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molecules that polarize light to the right/clockwise (+)
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molecules that can rotate the angle of polarized light are...
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optically active
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periodic table trend: atomic weights
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increases from L to R, U to D
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R configuration
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clockwise
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S configuration
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counterclockwise
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When denoting the configuration in a name, don't forget to add...
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(R) or (S) next to the carbon number!!!
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A racemic mixture is...
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an equal mix of dextrorotatory and levatorotatory forms
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addition reactions
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two reactants form on product
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subtraction reactions
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two reactants exchange parts to make two new products
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elimination reactions
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one reactants splits into two new products (H20) often a product
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rearrangement reactions
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a single reactant reorganizes its bonds and atoms to yield an isomeric product
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two ways to break a covalent bond are...
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symmetrically (radical) and unsymmetrically (polar)
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symmetrical bond breaking
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one electron goes with each product fragment (fish hook arrow), creates radicals
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unsymmetrical bond breaking
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both electrons go with one product fragment
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symmetrical bond making
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one electron donated to form new bond from each reactant, radicals bond
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unsymmetrical bond making
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two electrons donated to form new bond from one reactant, have even numbers of electrons, more common
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radicals are highly...
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reactive! because they usually have seven electrons in their octet, they'll bind to anything to get a full shell
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radicals fill their octet by....
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binding with an atom from another reactant, creates another radical OR by taking an electron from a double bond, binds to the molecule but causes the molecule to become a radical
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Steps of methane chlorination
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inititation, propagation, termination
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polar reactions occur because...
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of electrical attraction between positively and negatively polarized centers on functional groups
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nucleophile
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electron-rich, either because it has a negative charge or has a functional group with a lone pair, or because it has a negatively polarized functional group
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electrophile
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electron-poor, either because it has a positive charge or a vacant orbital, or because it has a positively polarized functional group
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electron poor
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+ (needs electrons to become neutral)
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electron rich
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- (gets rid of its electrons to become neutral)
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number of stereoisomers
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2^# of chirality centers
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gauche interactions
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must be at positions next to each other (ex. 1 and 2), 3.8 kJ/mol
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activation energy vs. transition state
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the energy difference between the products and reactants which determines how fast the reaction occurs (small G is faster) vs. the highest energy structure of that stage of the reaction, higher in energy than intermediate rxn product
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physical properties: enantiomers vs. diastereomers
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identical: different
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acid-base reactions
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H-A + :B+ <==> :A- + H-B
acids donate protons, bases accept |
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isopropyl
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CH3CHCH3
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sec-Butyl
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CH3CH2CHCH3 |
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isobutyl
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CH3
| CH3CHCH2--- |
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tert-Butyl
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CH3
| CH3--C-- | CH3 |
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isopentyl
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CH3
| CH3CHCH2CH2-- |
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neopentyl
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CH3
| CH3--C--CH2-- | CH3 |
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tert-pentyl
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CH3
| CH3CH2--C-- | CH3 |
