chapters 5-6-7 Flashcards
constitutional isomers
same molecular formula but different structural formula
stereoisomers
differ in 3d arrangement of atoms
conformation
different versions of a molecule assuming that free rotation is paused
torsional strain
strain caused by groups eclipsing and wanting to twist away from each other
steric stain
strain caused by the repulsion of groups in close proximity
angle strain
strain caused by angles that are reduced
what are the strains in cyclopropanes
- lots of angle strain because their bond angles are of 60 instead of 109.5
-all of their hydrogens are eclipsed so torsional strain
what are the strains in cyclobutanes
-torsional strain if it is flat because all h will be eclipsed but less torsional strain if 2 c up and 2 c down because they will all be staggered
-steric strain due to axial positions
-lots of angle strain since angles are of 90 instead 109.5
what makes for a chiral molecules
-at least one chiral c (Sp3 Carbon with all different groups)
-no plane of symmetry
-# of possible stereoisomers = 2^n where n is the # of chiral C
what is the opposite of chiral
achiral
what is a miso compound
a molecule that is superimposable with its mirror image
what is a racemic mixture
an equal amount of both enantiomers
what does a junction in a fisher projection represent
a chiral carbon
what does a vertical line represent In a fisher projection
substituents going into the plane
what does a horizontal line represent in a fisher projection
a substituent coming out of the plane
clockwise
R
counterclockwise
S
1R and 1S (1 chiral center)
enantiomers
1R and 1R (1 chiral center)
same molecule
2R and 2S (2 chiral centers)
enantiomers
4R (2 chiral centers)
same molecule
3R 1S (2 chiral centers)
diastereoisomers
what is an addition reaction
a reaction that has a double or a triple bond of some sort and is added a group to one of the c that makes this bond
what is an elimination reaction
a reaction where a molecule is taken 2 groups to from a ∏ bond
what is a substitution reaction
a group taking the place of another one on a molecule
what is a rearrangement reaction
an atom that changes place on a molecule (not a pair of electron like resonance)
electron rich
an atom that has extra electrons and looks for positive charge in the nucleus
electron poor
deficiant in electron, wants more
electrophile
looking for more electrons
nucleophile
wants positive charge
what is the rate determining step in a mechanism
the slow step
what’s a mechanism
a step by step description of how a reaction occurs :
- which bonds break
-which bonds are formed
-in what order
what are the two ways a bond is made or broken
symmetrical where an electron goes to each atom in the bond
unsymmetrical where the two electrons go on the same atom
how is the movement of electrons shown and where do they start from and where do they go
arrows show the movement of electrons from a nucleophile to an electrophile
what charge can a nucleophile have and what will it be after donating a pair of electrons
the nucleophile can start as negative or neutral
when it donates, the neutral becomes positive or the negative becomes neutral
what charge can an electrophile have and what will it be after accepting a pair of electrons
the electrophile can start as positive or neutral
after receiving, the neutral would become negative or the positive becomes neutral
what is an endothermic reaction
△H positive
what is an exothermic reaction
△H negative
what is △G
Gibbs free energy and entropy
what does a positive △G mean
an endergonic reaction so not spontaneous. k is small
what does a negative △G mean
an exergonic reaction so spontaneous. k is large
what is the formula for △G
△G=-RTlnKeq
what is △S
a change in entropy
what formula is related to △S
△G=△H-T△S
if a reaction is product favored, what will be its Gibbs free energy
negative
