Shared Flashcard Set

Details

MCAT Hydrocarbon Properties
Melting, Boiling, Intramolecular Forces
30
Organic Chemistry
Not Applicable
07/10/2011

Additional Organic Chemistry Flashcards

 


 

Cards

Term
Branching
Definition

Tends to inhibit the van der Waals forces by reducing the surface area available for intermolecular reaction.

 

Reduces attractive foraces between molecules and lowers both melting and boiling point.

Term
Molecular Weight
Definition

The greater the molecular weight, the greater the surface area to interact, the greater the van der Waal's forces.

 

Higher melting and boiling points.

Term
Hydrogen bonding
Definition

Occurs between a hydrogen bond donor (F,O,N) and a hydrogen bond acceptor (a lone pair of e's on a nitrogen, oxygen or flourine in another molecule).

 

The more donors and acceptors in a molecule, the higher the MP and BP.

Term
Carbocations
Definition

(Carbonium Ions)

Positively charged species with a full positive charge on carbon.

 

Reactivity is based on which carbon bears the charge.

 

Will always be sp2 hybridized on the MCAT

Term
Alkyl Radicals
Definition

Reaction intermediates that contain one unpaired electron.

 

Reactivity is based on which carbon bears the negative charge.

 

Will be sp2 on the MCAT with the unpaired electron in the p orbital.

Term
Carbanions
Definition

Negatively charged species with a full negative charge localized on carbon.

 

Reactivity is based on which carbon bears the negative charge.

 

On the MCAT it will be sp2 hybridized with the lone pair in an unhybridized p orbital OR it may be sp3 hybridized with the lone pair in an sp3-hybridized orbital.

Term
Stability of Carbocations
Definition
3o<--2o<--1o<--methyl
Term
Stability of Alkyl Radicals
Definition

3o<--2o<--1o<--methyl

Term
Stability of Carbanions
Definition

methyl-->1o-->2o-->3o

 

Term
Reactivity of Carbocations
Definition

3o-->2o-->1o-->methyl

 
Term
Reactivity of Alkyl Radicals
Definition

3o-->2o-->1o-->methyl


Term
Reactivity of Carbanions
Definition

methyl-->1o-->2o-->3o

Term
Energy of Carbocations
Definition

3o-->2o-->1o-->methyl

Term
Energy of Alkyl Radicals
Definition

3o-->2o-->1o-->methyl

Term
Energy of Carbanions
Definition

 

methyl-->1o-->2o-->3o

 

 

Term
Inductive Effects
Definition
Stabilize charge through sigma bonds.
Term
Resonance Effect
Definition
Stabilize charge by delocalizing through pi bonds.
Term
Electron Withdrawing
Definition
Pull electrons towards themselves through sigma bonds.
Term
Electron Donating
Definition

Donate electron density away from themselves through sigma bonds.

 

Alkyl groups will always be electron-donating on the MCAT.

Term
Inductive Effect
Definition
The stabilization of reaction intermediates by the sharing of electrons through sigma bonds.
Term
Conjugated System
Definition

A system containing three or more atoms that each bear a p orbital.

 

These orbitals are aligned so that they are all parallel, creating a possibility of delocalized electrons.

Term
Localized electrons
Definition
Electrons that are confined to one orbital, either a bonding orbital between two atoms or a lone pair orbital.
Term
Delocalized Electrons
Definition

Electrons that are allowed to interact with orbitals on adjacent atoms and are no longer confined to their orginal "space"

 

The electron density is spread out.

Term
Alkoxide Ion
Definition

Alcohol with the H removed.

 

Very reactive since the electrons on the O have no adjacent p orbital or pi system.

 

Alkoxide ion is thus a strong base.

Term
Carboxylate Ion
Definition

Electrons on the negatively charged oxygen are adjacent to the pi bond and thus delocalized.

 

This leads to greater stability and thus higher acidity of the conjugate acid.

Term
How to determine acidity of two different compounds.
Definition

Remove the H and create the resulting base.

Whichever base is more stable is the stronger acid.

 

If resonance leave a negative charge on C, this is less stable than on electronegative O.

Term
Organic Compound Acidity
Definition
Strong Acid > Sulfonic Acids > Carboxylic Acids > Phenols > Alcohols and Water > carbonyl compounds (aplha H) > sp hybridized C-H bonds > sp2 hybridized C-H bonds > sp3 hybridized C-H bonds
Term
Ring strain
Definition

Arises when bond angles between ring atoms deviate from the ideal angle predicted by the hybridization of the atoms.

 

Hydrogenating these cycloalkenes with angle strain over metal causes them to break open into single stranded alkanes.

Term
Which position is most favorable on the chair formation?
Definition
Equitorial
Supporting users have an ad free experience!