Ochem 1 Flashcards
Hydrazine
N2H4
Vinyl
Define observed rotation of a molecule
- What determines it?
degree to which a sample rotates PPL
- determined by:
- []
- length of tube, etc.
Why are alcohols soluble in water?
They can H bond with water
Cycloalkanes and ring strain
- How much ring strain do big, small, bicyclic & monocyclic cycloalkanes have?
- Cycloalkanes w/ LESS than 6 C’s have increasingly more ring strain
- Really BIG (10+) rings have enough freedom to approximate 109.5º
- BICYCLICring systems haveMOREring strain thanMONOcyclic rings
If you see C6H5, what is it?
a BENZENE!
- not a straight chain
- since it has π bonds, it is unsaturated
1º,2º,3º OH groups have 1,2, and 3 ___ ___ which do what to charge?
What does this mean?
Have 1,2, and 3 donating groups to destabilize charge
this is why 3º is less acidic than 1º
Hückel’s Rule (for aromaticity)
to exhibit aromaticity
a ring must have EXACTLY __+__ electrons
to exhibit aromaticity
a ring must have EXACTLY: 4n+2π electrons
From what I’ve gathered, “n” is just 1 (at least it is for benzene…( 4(1) + 2π= 6 )
Hemiketal
Physical properties of alkanes
- Soluble/Insoluble in water?
- Low/High density?
- polar/non-polar?
- What increases BP?
- What decreases it?
- What increases MP?
- insoluble in water
- very low density
- non-polar
- BP increases with increasing chain length and/or MW
- BP decreases with increased branching (decreased symmetry)
- MP increases with increasing chain length and/or MW
Cyclic rings create ___ ___ and make bond angles do what?
- ring strain
- make bond angles deviate from preferred 109.5º
Alkenes are _____s!
Why?
Nucleophiles!
- π bonds are e’ dense and will attach E:philes
- forming a new bond to one of the C’s
- and leaving a CCI on the other
- CCI then attacked by a Nu:
What does an SN2 rxn look like?
Rank BOND REACTIVITY for:
- Single bonds
- Double bonds
- Triple bonds
triple>double>single
more reactive bc of π bonds
3º ROHs can only be oxidized into ___?
PSYCHE!
They cant be oxidized at all!
1º ROH can be oxidized into?
1º ROH⇒Aldehydes⇒Carboxylic Acids
Alcohols are less/more acidic than water
- Rank alcohol acidity
LESS acidic than water
- ROH acidity increases from:
- (most acidic) 1>2>3 (least acidic)
Imine
Hybridization:
sp3, 1 LP
Trigonal Planar
Hybridization:
sp3d, 2 LPs
T-shaped
What is a racemic mixture a mixture OF?
50/50 mix of R and S enantiomers
Anomers
- If anomeric OH/OR group and CH2OH group are on opposite sides of the ring, what kind of anomer is it?
ALPHA anomer
on the “Alpha-site side”
Alcohols behave as either: ___s or as a ___
1) Nucleophiles
* (the lone pair on oxygen acts as a Lewis base)
2) Lewis acids
- ..when they are oxidized to carbonyl groups
- the oxygen ACCEPTS A PAIR OF ELECTRONS (Lewis Acid) from the O-H bond as the proton is abstracted
Hybridization:
sp3d2, 1 LP
Square Pyramidal
Are Alkyl substituents strong or weak e’ donating groups?
weak
Absolute conformation (__ & __)how do you assign priority to 4 R groups?
Assign priority starting with:
HIGHEST MW
(heavier=higher priority, i.e. 4)
(lighter, like H=lower priority, i.e.1)
If 1–>3 is clockwise=R
If 1–>3 is counter clockwise =S
Gringard Synthesis:
Describe the 2 steps (using R-MgBr)
1) Mg has VERY LOW ELECTRONEGATIVITY
- so the R group in R-MgBr attacks the electrophilic carbonyl C
- Occurs in single step
- kicking e’s in C=O bond onto the oxygen
2) (-) charged oxygen is protonated
* yielding an alcohol
What are diastereomers?
Have same MF & connectivity (like steroisomers)
- are NON-identical, NON-superimposable*
- mirror images*
Amine
Anhydride
Benzyl
Sulfone
Hybridization:
sp2, no LPs
Trigonal Planar
Ex: BF3
HYbridization:
sp3d, no LPs
Trigonal BIpyramidal
Ex: PF5
Hybridization:
sp3d, 3 LPs
Linear
ex: XeF2
Rank bond STABILITY for:
- Single Bonds
- Double Bonds
- Triple Bonds
Explain what makes the least stable one the least stable
single>double>triple
- Triple bond is LESS stable because it has 2 reactive π bonds!
RANKING resonance structures
- You want MORE ____s, LESS _____
- The most STABLE species has the most WHAT?
MORE bonds, LESS charges
The most stable species has the MOST POSSIBLE RESONANCE STRUCTURES
Describe the 2-step formation of:
- TOSYLATES / MESYLATES
-
ROH attacks X (via SN2)
- kicks off X
- H is abstracted by X ion
Mesylates and Tosylates are desirable because they make very good LGs that will react readily with almost any nucleophile
Define “LEVOROROTARY”
- Using FISCHER PROJECTIONS, differentiate b/t D- Glyceraldehyde and L-Glyceraldehyde
compound rotates light
counter-clockwise (-)
Acetyl
2 molecules have the same RELATIVE CONFIGURATION if:
- Their 3D arrangement is ___, but they have 1 (and ONLY 1) ___-____ _____
SAME RELATIVE CONFIGURATION if:
Their 3D arrangement is IDENTICAL, but they have 1 (and ONLY 1) NON-IDENTICAL SUBSTITUENT
Hybridization:
sp3, no LPs
TETRAHEDRAL
Structural/ Constitutional Isomers have the SAME____, but different _____
Same MF
BUT
Different connectivity
ETHERS, ROR’, are excellent…?
Solvents!
2º ROHs can ONLY be oxidized into ___
Can they be oxidized any further, like 1° ROHs?
Ketones
Can NOT be further oxidized
What are the 2 types of reactions you’ll
see ETHERS, ROR’, used in?
- Ethers will almost ALWAYS be the SOLVENT
- ∴ wont participate in rxn
- If Ethers DO react, it’ll only be after the O- is protonated by a strong acid (HCl)
- resulting in a carbocation intermediate
- which would then be attacked by a nucleophile
Nitrile
Ester
HINT: Ester drinks COORS
What are a few common OXIDIZING AGENTS?
HINT: OKPeePee!
- O3Cr2O7
- KMnO4
- PCC
- PDC
List 4 characteristics of π bonds
- prevent rotation
- weaker than sigma bonds
- less stable
- more reactive
Aldehyde
In DEHYDRATION of an ROH:
- What is favored by a HOT, concentrated acid?
- What is favored by a COLD, dilute acid?
In a dehydration reaction, what is the MAJOR product?
Alkene
- is favored by a hot, concentrated acid
Alcohol
- is favored by a cold, dilute acid
Major** product is the **more substituted
(more stable) alkene
Describe SN2 rxns
Rate depends on [] of 2 species
- so its SECOND order
- ONE step
STEP:
-
Backside attack of Nu:
- w/ simultaneous ejection of LG
Carboxylic acid
COOH
Alkyl group
Hydrocarbons ONLY!!!
Define a “Base” in an ochem reaction
- What do they do to protons?
- Are they electron dense or deficient?
- What kind of charge do they have?
ABSTRACT protons
- are electron DENSE
- have full or partial (-) charge
Dehydration of ROH: synthesis of an ___.this is an ___ rxn
alkeneis an equilibrium rxn
What are Meso cpds?Why dont they have optical activity?Are they diastereomers? Why/Why not?
- -have 2+ chiral centers AND a plane of symmetry
- POS cancels out optical activity
- ARENT diastereomers, b/c diastereomers are PAIRS of cpds.
- Meso cpds are single cpds with a POS-
- Therefore, can’t be diastereomers NOR enantiomers
Define “ALIPHATIC”
- If something has a benzene ring, is it aliphatic or not?
Relating to organic compounds whose carbon atoms are linked in open chains
- either straight or branched
rather than containing a benzene ring
Something is either ALIPHATIC or AROMATIC
Example:
Alkanes, alkenes, and alkynes are aliphatic compounds