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OCHEM 2nd Language
OCHEM 2nd Language
56
Organic Chemistry
Undergraduate 2
03/01/2019

Additional Organic Chemistry Flashcards

 


 

Cards

Term
formal charge
Definition
charge associated with an atom that does not exhibit the expected number of valence electrons
Term
the 2 commandments of drawing resonance structures
Definition
1: never break a single bond
2: never exceed an octet for second-row elements
Term
the 3 questions that determine whether or not a resonance structure can be drawn
Definition
1: Can we convert any lone pairs into pi bonds without breaking the 2 commandments?
2: Can we convert any pi bonds into lone pairs without breaking the 2 commandments?
3: Can we convert any pi bonds into pi bonds without breaking the 2 commandments?
Term
the 5 patterns you should recognize to become proficient at drawing resonance structures
Definition
1: a lone pair next to a pi bond 2: a lone pair next to C+ 3: a pi bond next to C+ 4: a pi bond between 2 atoms, where one of those atoms is electronegative 5: pi bonds going all the way around a ring
Term
what a lone pair next to a pi bond means for resonance
Definition
you can bring down the lone pair to form a pi bond and kick up the pi bond to form a lone pair
[image]
Term
what a lone pair next to C+ means for resonance
Definition
the lone pair forms a pi bond with that C+
Term
what a pi bond next to C+ means for resonance
Definition
the pi bond moves such that a new pi bond is formed and another C becomes C+
Term
what a pi bond between 2 atoms, where one of those atoms is electronegative means for resonance
Definition
the electrons in the pi bond gravitate towards the electronegative element
Term
what pi bonds going all the way around a ring means for resonance
Definition
the pi bonds can move in a circle
Term
conjugated double bonds
Definition
alternating double and single bonds
[image]
Term
the 4 rules of assessing the relative importance of resonance structures
Definition
1: OCTET; the most important resonance structures have the greatest number of filled octets and covalent bonds
2: FORMAL CHARGES; the structure with fewer formal charges is more important
3: NEGATIVE CHARGE ON ELECTRONEGATIVE ELEMENT; other things being equal, a structure with a more negative charge on a more electronegative element will be more important
4: LEWIS STRUCTURES; resonance structures that have equally good Lewis structures are described as equivalent and contribute equally to the resonance hybrid
Term
resonance structures to not draw
Definition
insignificant structures
Term
how to determine the willingness of an acid to donate its proton
Definition
by determining the stability of the negative charge on its conjugate base
Term
the 4 important factors of acid-base reactions
Definition
1: what atom is the charge on?
2: resonance
3: induction
4: orbitals
Term
periodic trend in electronegativity
Definition
northeast
Term
periodic trend in ability to stabilize a charge (polarizability)
Definition
southeast
Term
how resonance makes a molecule more acidic
Definition
the charge on its conjugate base is spread over a wider area
Term
induction (in the context of acid-base reactions)
Definition
"pulling" of electron density caused by differences in electronegativity
Term
the shapes of sp, sp2, and sp3 orbitals
Definition
[image]
Term
why a proton on a triple bonded carbon is more acidic
Definition
because the lone pair in the conjugate base is held more closely to the nucleus
Term
how closely orbitals hold lone pair electrons to nucleus
Definition
sp more closely than sp2 more closely than sp3
Term
factors of acid-base rxns in order of importance
Definition
atom, resonance, induction, orbital (ARIO)
1: atom the charge is on
2: resonance on conjugate base
3: induction
4: orbital that has the negative charge
Term
important exception to the order of importance of factors in acid-base rxns
Definition
[image]
Term
why the conjugate base on the left is more stable than the conjugate base on the right
[image]
Definition
because a negative charge on an sp hybridized carbon is more stable than a negative charge on an sp3 hybridized nitrogen
Term
another factor that can affect the stability of conjugate bases
Definition
interactions with solvent (solvating effect)
Term
solvating effect
Definition
greater steric bulk around atom with negative charge makes corresponding conjugate acid less acidic
Term
pKa vs. acidity
Definition
lower pKa means more acidic
Term
rate of change in pKa
Definition
logarithmic
example: pH 3 is 10 times more acidic than pH 4
Term
which side of an acid-base rxn is favored when at equilibrium?
Definition
the side that has the more stable negative charge
Term
sterics
Definition
if the geometry of molecules prevents them from getting close, then there can'e be a rxn
Term
how covalent bonds are formed
Definition
by the overlapping of orbitals
Term
number of sp3 orbitals
Definition
4
Term
number of sp2 orbitals
Definition
3
Term
number of sp orbitals
Definition
2
Term
bond angle for tetrahedral (sp3 hybridized)
Definition
109.5 degrees
Term
bond angle for trigonal planar (sp2 hybridized)
Definition
120 degrees
Term
bond angle for linear (sp hybridized)
Definition
180 degrees
Term
the 5 parts to naming organic molecules
Definition
1: stereoisomerism
2: substituents
3: parent
4: unsaturation
5: functional group
Term
stereoisomerism
Definition
indicates stereocenters (R, S) and whether double bonds are cis/trans
Term
substituents
Definition
groups connected to the main chain
Term
parent
Definition
main chain
parent chain
Term
unsaturation
Definition
identifies if there are any double or triple bonds
Term
functional group
Definition
the group after which the compound is named
Term
some elements that gent named as substituents instead of functional groups
Definition
halogens
Term
when a compound has double and triple bonds, which bonds get listed first?
Definition
the double bonds
Term
cyclo-
Definition
ring
this is te prefix for carbon atoms in a ring
Term
the functional group that needs to be connected to the parent chain
Definition
the functional group with higher priority
Term
the carbon chain that has to be the parent chain
Definition
the one with the double or triple bond, if there is one
Term
hierarchy when finding the parent chain
Definition
1: functional group
2: double bond
3: triple bond
Term
stereoisomers
Definition
isomers that differ in spatial orientation
Term
hierarchy when numbering the parent chain
Definition
1: functional group
2: double bond
3: triple bond
4: substituent
Term
how to account for functional groups when naming molecules
Definition
placing the number in front of the suffix or in front of the parent chain

example:
hexan-2-ol or 2-hexanol
Term
how to account for substituents when naming molecules
Definition
putting the number of the substituent immediately in front of the substituent

example:
2-chlorohexane
Term
how to account for multiple substituents when naming molecules
Definition
number each one alphabetize by substituent (not di, tri, tetra, etc.)
Term
how to account for stereoisomerism when naming molecules
Definition
put it at the beginning of the name and number accordingly

example:
2-cis-4-trans or (2R,4S)
Term
conformations
Definition
the various positions available to a molecule
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