Chapter 5,6,7,8 Flashcards
(127 cards)
What is the degree of unsaturation?
The total number of pi bonds and rings in a compound.
How do you calculate the degree of unsaturation from a molecular formula?
Start with the formula for a saturated hydrocarbon (CnH2n+2) and subtract 2 hydrogens for each pi bond or ring in the molecule.
What suffix is used for alkenes in IUPAC nomenclature?
-ene
What are the key rules for naming alkenes?
- The longest continuous chain containing the carbon-carbon double bond is numbered to give the functional group the lowest possible number.
- For multiple double bonds, use “diene,” “triene,” “tetraene,” etc.
- State substituents before the name of the chain, with numbers to designate position.
How are stereoisomers of alkenes named?
E/Z prefixes to indicate the arrangement of groups around the double bond.
What is a vinylic carbon?
A carbon that is part of the double bond.
What is an allylic carbon?
A carbon directly adjacent to a vinylic carbon.
What are the vinyl and allyl groups?
Vinyl group: -CH=CH2 Allyl group: -CH2CH=CH2
What is the hybridization of carbon atoms in a double bond?
sp² hybridization
How is a double bond formed?
A sigma bond forms by overlap of sp² orbitals, and a pi bond forms by side-to-side overlap of unhybridized p orbitals.
Why must all six atoms of a double-bond system be in the same plane?
For effective overlap of the p orbitals to form the pi bond, all atoms must lie in the same plane.
What determines the kinds of reactions a compound undergoes?
The functional group of the compound.
What is an electrophile?
An electron-deficient species attracted to electron-rich species.
Electrophiles have a positive charge, partial positive charge, or incomplete octet.
What is a nucleophile?
An electron-rich species that has electrons to share and reacts with electrophiles.
What is the difference between a Lewis acid and a Lewis base?
Lewis acids accept a share in a pair of electrons, while Lewis bases donate a share in a pair of electrons.
What’s the difference between a base and a nucleophile?
A base reacts with a proton, while a nucleophile reacts with something other than a proton.
What is the mechanism of a reaction?
The step-by-step description of the process by which reactants are changed into products.
What do curved arrows represent in reaction mechanisms?
Curved arrows show the movement of two electrons from a nucleophile toward an electrophile.
What are the rules for using curved arrows?
- Each arrow represents movement of two electrons
- The tail starts at the electron source (bond or lone pair)
- The head points to where electrons end up (atom or bond)
- Arrows flow from nucleophile to electrophile
What is a transition state?
The point in a reaction where bonds are partially broken and partially formed.
How is a transition state represented in diagrams?
Using dashed lines to indicate partially formed or broken bonds, and with square brackets with a double dagger [‡].
What is the difference between a transition state and an intermediate?
Transition states have partially formed bonds and cannot be isolated, while intermediates have fully formed bonds and can potentially be isolated.
What does thermodynamics tell us about a reaction?
The relative amounts of reactants and products present at equilibrium.
What does kinetics tell us about a reaction?
How fast the reaction occurs.