Orgo review Flashcards
Explain the difference between sigma and pi bonds
Sigma bonds are the result of end-to-end overlap of orbitals and make single bonds.
Pi bonds are the result of side-to-side overlap of overbitals and result in double or triple bonds.
Explain the difference between sp, sp2 and sp3-hybridized carbon atoms.
sp carbons have two groups bonded to them and have a 180 degree bond angle between those groups
sp2 carbon atoms have three groups bonded 120 degrees apart
sp3 carbons have four groups bonded and are 109.5 degrees apart
Define unsaturated
An unsaturated molecule contains one or more pi bonds, such that it does not contain the maximum amount of hydrogen
Rank the four types of carbocations from least to most stable
Methyl, primary, secondaey, tertiary
Explain the difference between structural isomers, conformational isomers, and stereoisomers
Structural isomers are two molecules that have the same molecular formula, but different connectivity
Conformational isomers have the same molecular formula, but differ in their rotations about single bonds.
Stereoisomers have the same molecular formula and connectivity of atoms, but the groups differ in spatial arrangements in the molecule.
What is another name for geometric isomers?
Geometric isomers are a type of diastereomer. They can also be referred to as cis/trans isomers about a double bond or ring.
What are two types of stereoisomers
Geometric isomers and optical isomers are stereoisomers
What is the most stable conformation of methylcyclohexane?
The chair form with an equatorial position (Pointing to the side)
What is a racemic mixture?
A 50/50 mixture of two enantiomers
What is a nucleophile?
What is an electrophile?
A nucleophile is a species that is electron rich and is attracted to something that is electron deficient to donate a pair of electrons. It usually has a full or partial negative charge and/or a lone pair of electrons
An electrophile is a species that is electron deficient, so it is attracked to electron rich species. It usually has a faull or partial positive charge associated with it.
Define Lewis acid and Lewis Base
A Lewis acid is an electron pair acceptor, or an electrophile.
A lewis base is an electron pair donor, or nucleophile.
Is inversion of configuration seen in an Sn1 or Sn2 reaction?
Which yields a racemic mixture
Sn2 reaction results in inversion of configuration
Sn1 results in a racemic mixture
Which will a more substituted substrate favor, Sn1 or SN2?
Sn1 is favored, because the first step is the formation of a carbocation, and more substituted carbocations are more stable.
Which reaction mechanism (Sn1/Sn2) is dependent on nucleophile concentration?
Sn2 is dependent on nucleophile concentration
What type of isomers are tautomers?
Structural isomers
What is the difference between a hydride, a proton, and a hydrogen?
A hydride is H-, a proton is H+ and a hydrogen is H* (radical)
What is an imine?
The nitrogen equivalent to a ketone or aldehyde
What type of mechanism is the saponification of a triglyceride?
Saponification is an addition-elimination reaction
Name the carboxylic acid derivatives from least to most reactive
Amide, ester, acid anhydride, acid halide
Give the approximate infrared stretching frequencies for the following functional groups:
O-H C=O C=C
O-H 3,200-3600 cm-1
C=O 1,700 cm-1
C=C 1,650 cm-1
What does the splitting in a 1H NMR spectrum indicate?
What does the number of signals in the spectrum show?
The number of nonequivalent hydrogens on the adjacent carbon atoms
The number of nonequivalent hydrogens in the molecule
Are molecules with five or fewer carbons that also bear a functional group more soluble in the aqueous or organic layer in an extraction?
Molecules with <5 carbonds are more soluble in the aqueous layer
What functional groups can be manipulated in an extraction to alter the solubility of a molecule?
Carboxylic acids, phenols, and amines
Do polar or nonpolar molecules have lower Rf values?
Polar molecules have lower Rf values
For each chromatographic technique, name the property that is key to their function
TLC, GC, SEC, affinity chromatography, and ion exchange
TLC - polarity
GC - polarity and boiling point
SEC - size
Affinity - IMF
Ion exchange - charge and size
Are animal amino acids in the D or L configuration?
L
What are two common techniques to synthesize amino acids?
Strecker and Gabriel-malonic ester syntheses
