Ochem Quiz Flashcards

Functional group
Terms Definitions
(CH3)2CHCh2CH2Cl---Gabriel synthesis---> ?
Weak nucleophiles favor
aromatic H NMR
E and delta h
Sn1 on allylic C
Attraction of permanent dipoles
Strong nucleophiles in high concentrations favor
Sn2 if halide on 3
Nonpolar, Hydrophobic AAs
alanine glycine
isoleucine leucine
methionine phenylalanine
proline tryptophan valine
- either aliphatic or aromatic
- associate w/each other in water
- found on the interior
polar aprotic solvents (SN1 or SN2)
Larger halogens __________ the boiling point
Good nuc effect on Sn1
No effect
Liquid portion resulting from a filtration
- electron-deficient species
- have a full or partial positive charge
- electron pair acceptors
Sigma bond
symmetrical about its axisOverlapping two s forms sigma and sigma* orbitalsEnd to end overlap of 2 p orbitals forms pi and pi*
An imide is a functional group consisting of two carbonyl groups bound to a primary amine or ammonia.
mechanism that occurs in the presence of a polar protic solvent (greater the polarity the faster the reaction rate)
Effect of Solvent
Polar protic solvents:
-ex:HOH and ROH
-favor Sn1 reactions becasue the ionic intermediates (both cations and anions) are stabilized by solvation
Polar aprotic solvents:
-ex: DMF, DMSO, DMAc
-Favor Sn2 reactions because nucleophiles are not well solvated, and therefore, are more nucleophilic.
the acid or electrophile(Br-) adds to the least subsituted carbon while the hydrogen adds to the carbon with most hydrogens
Which is the stronger nucleophile h20 or c:-
Amine Reactions from HONO
Ar-NH2 -(HONO/0-5C)-> Ar-N2+ (arenediazonium salt)
amphipathic molecules
- contain a negatively charged carboxylate grp that is hydrophilic & a long saturated or un-saturated hydrocarbon tail that's hydrophobic
- fatty acids are amphipathic molecules
- soap is a triglyceride from animal fat thru saponification
105°Two atoms bound to central atom with lone pair
Alkylation is the transfer of an alkyl group from one molecule to another.
Bond dissociation energy
Energy needed to homolytically cleave a covalent bond
-Ethers having the oxygen atom in a three-membered ring.
-Also called oxiranes or alkylene oxides.
-C-O-C bond angle for an epoxide = 60
-angle strain makes epoxides more reactive than other ethers
Markovnikov's Rule
With an unsymmetrical alkene, HX can add to the double bond to give two constitutional isomers, but only one is actually formed.
Markovnikov's rule:
- the electrophile (often H) adds to the sp2 carbon that is bonded to the greater number of hydrogens.
- in the addition of HX to an unsymmetrical alkene, the H atom adds to the less substituted carbon atom - that is, the carbon that has the greater number of H atoms to begin with
- "them that has, gets"
- results in formation of the most stable carbocation.
condensed structure
a shorthand way of drawing structures in which C-C and C-H bonds are understood rather than shown
Grignard Reagent
R-MgBr, Synthesized by adding Mg to some halide in diethyl ether or THF
- molecules that have the same mol. formula & connectivity, but different spatial arrangement
- R vs. S
concerted reaction
all bond breaking and bond making occurs in a single step
Metal acetylide
A metal acetylide is an alkyne for which the terminal proton has been replaced by a metal such as sodium or an organolithium.
Stereochemistry of sn2
backside attack and inversion at a stereogenic center
Alkyne Bonding and Structure
Alkynes have formula: CnH2n-2 (DU= 2)
Triple bond consists of two pi bonds and on sigma bond.
Each carbon is sp hybridized with a linear grometry and bond angles of 180 degrees.
Terminal alkyne: triple bond at end of the carbon chain (H directly bonded to a caarbon atom of the triple bond)
Internal alkyne: has a carbon atom bonded to each carbon atom of the triple bond
Preparation of COOH
R-MgBr + CO2 --> R-COO- MgBr+ -(HCl/H2O)-> R-COOH
mass spec
- uses high speed electron beam to ionize the sample
- detector reads masses of particles
Dual Nature of light
Light undergous both interference and diffraction: wavelenthPhotoelectric effect behaves like a massless paprticle: photon
Elimination bonds
Two sigma bonds are groken and a pi bond is formed
Alcohol Systematic Nomenclature
Step 1) Find the longest carbon chain containing the carbon bonded to the OH group
- change the -e ending of the parent alkane to the sufix -ol
Step 2) Number the carbon chain to give the OH group the lower number, and apply all other rules of nomenclature.
- name and number the subsituents
bond angle
the angle formed by two bonds to the same atom
4 ways to denature a protein:
1. urea (disrupts H-bonding interactions)
2. extremes of pH
3. extremes of temperature
4. changes in salt concentration (tonicity)
When will carbocation rearrangements occur?
Only to an immediately adjacent carbon (1,2 - shift not 1,3-)
Only whenrearrangement leads to a more stable carbocation.
Carbocation Stability and Markovnikov's Rule
The basis of Markovnikb's rule is the formation of a carbocation in the rate-determining step of the mechanism.
In the addition of HX to an unsymmetrical alkene, the H atom is added to the less substituted carbon to form the more stable, more substituted carbocation.
Weight Average MW
Record the weight of each chain of a particular length, sum and divide by total weight of sample.
s is entropy (disorder), h is enthalpy
why does tietery alcohol dehydrate faster than secondary and primary
reason is because tertiary can form the most stable carbocation.
Competition between Sn1 and E1 Reactions
Sn1 and E1 reactions have exactly the same first step- formation of a carbocation
They differ in what happens to the carbocation.
hydrogenation of the π bonds of alkynes
w/ Lindlar catalyst
(aka. poisoned catalyst)
- stops hydrogen reduction of alkynes at the alkene stage
- cis-addition
When is the reaction Sn1 Sn2 E1 or E2?
Good nucleophiles that are weak bases favor substitution over elimination
These include: I-, Br-. HS-, -CN, CH3CO-
least leavability
Cyclic Ester
alkene-----?---------> epoxide ring
alkyne C NMR
Addition Reactions of Cyclohexene
Halohydrin formation
Hydroration - oxidation
oximerouration - reduction
C−H stretch
- variable intensity
Thiocyanates are rganic compounds containing the functional group SCN.
List compounds with pKa~10
propinated amines
solution to a wave equation
N=1 l=osymmetrically positive or negative with high prob at nucleus and exponentially lower with distance
mechanism that has anti periplanar stereochemistry to the leaving group
Useful Products Formed From Ethylene
Poly(vinyl chloride)
poly( vinyl acetate)
ethylene glycol
E1 vs Sn1 good nuc
Sn1 favored
R-CO-R + H-NR'2 -(H+)-> R2-C-OH-NR'2 -(H+/-H2O)-> Enamine (ene + amine) Useful as nucleophile for Sn2 with methyl halide, 1o haloalkane, alpha-haloketone, and alpha-haloester. Gives iminium hailde, which can be hydrolysed to give some iminium-halo ion and an O where the N was.
RCH₂X; X=NR₂; OR; halogen C NMR
Azo compound
Azo compounds refer to synthetic inorganic chemical compounds bearing the functional group in which two alkyl or aryl groups are bound respectively to two doubly bound nitrogens.
A cycloalkyne is a hydrocarbon which is the cyclic analog of an alkyne.
Nucleophiles attack
Electron deficient atoms (usually C) that are not H
Physical Properties
-Alchols, ethers, and epoxides having <_ 5 C's are h2o soluble becasue they each have an oxygen atom capable of hydrogen bonding to h2o.
-Alcohols, ethers, and epoxides having >5 C's are h2o insoluble because the nonpolar alkyl portion is too large to dissolve in h2o.
-Alcohols, ethers, and epoxides of any size are soluble in organic solvents.
Technique used to determine the number of chemical components in a mixture
Michael Reaction
1,4 nucleophilic addition of enolate anion or enamine to a,b-unsaturated carbonyl (done over EtO- and EtOH)
Organometallic Reactions
Strong Bases, Essentially R-; Also good nucleophiles (Can convert C=O or Oxiranes to R-C-OH (must add H2O to protonate!))
internal plane of symmetry in a molecule that contains chiral centers
An imine is a functional group or chemical compound containing a carbon-nitrogen double bond, often synthesised by the addition of an amine to a ketone or aldehyde followed by an elimination of water
The haloalkanes or alkyl halides are a group of chemical compounds, consisting of alkanes, such as methane or ethane, with one or more halogens linked, such as chlorine or fluorine.
Addition reactions
Elements are added to a starting material
Hydrohalogenation - Summary
Mechanism: the mechanism involves two steps
- the rate deteremining step forms a carbocation.
- rearrangements can occur.
Regioselectivity: Markovnikov's rule is followed. In unsymmetrical alkenes, H bonds to the less subtituted C to form the more stable carbocation.
Stereochemistry: Syn and anti addition occur; racemic mixtures are formed
E1 if halide on 3
Yes and beta H
Haworth Projections
Ring drawn planar, attachments up and down. Anomeric carbon on right with hemiacetal oxygen behind it. Alpha if anomeric OH down, Beta if up
1. charge the fxnal grp of
2. exploit acid/base properties of fxnal grps
3. add st.base --> to change any acid
- add wk.base --> to change stronger acid (Ka > Kb)
- add wk.acid --> to change stronger base
- add st.acid --> to change any base
gas chromatography
form of column chromatography in which the partitioning of the components to be separated takes place b/w a moving gas phase & a stationary liquid phase. This partitioning, or separation, b/w mixtures of compounds occurs based on their different volatilities.
base peak
the peak that has the highest relative intensity
Endothermic Reaction Transition States
-The transition state resembles the products more than the reactants.
-anything that stabilizes the product also stabilizes the transition state.
-lowering the energy of the transition state decreases Ea, which increases the reaction rate.
if there are two possible products of different stability in an endothermic reaction, the transition state leading to the more stable product is lower in energy, so this reaction should occur faster.
Aldehyde--?------> 2 -OH
Gringard with 1. R-Mg-X, ether/ 2. H3O
Ziegler-Natta Chain Growth Polymerization
No free radicals, less branching: TiCl4, AlR2, MgCl2
electrophilic aromatic substitution
aromatic compounds will act with VERY electrophilic reagents to undergo an overall substitution rxn for a H⁺ atom on the ring.
E2 mechanism
E2 is a model to explain a particular type of chemical elimination reaction in which there is a one-step process of elimination with a single transition state.
Pauli Exclusion Principle
There can be no more than two electrons in an orbital. Those electrons must have opposite spins
Epoxide Reaction with Nucleophiles: Regioselectivity
Nucleophile opens epoxide ring from the back.
Regioselective: in unsymmetrical epoxides, the nucleophile attacks the less substituted C.
Glass Transition Temperature Tg
The temperature at which a polymer goes from a hard glass to a rubbery solid
sp hybrid
2 new orbitals from 2s and 1 2plower E than original
Conversion of Alcohols to Alkyl Halides with HX
Substitution reaction do not occur with alcohols unless -OH is converted into a good leaving group.
The reaction of alcohols with HX is a general method to prepare 1, 2, and 3 alkyl halides.
Physical Properties of Alkenes
Most alkenes exhibit only weak van der Waals interactions, so their physical properties are similar to alkanes of comparable molecular weight:
- low melting points and boiling points
- melting and boiling points increase as the number of carbons increases becasue of increased surface area
- soluble in organic solvents, insoluble in wate (no matter how many C's)
The C-C single bond between an alkyl group and one of the double bond carbons of an alkene is slightly polar because the sp3 hybridized alkyl carbon donates electron density to the sp2 hybridized alkenyl carbon.
Arenediazonium Salt Reactions
H2O --> Ar-OH; HBF4 --> Ar-F; HCl or CuCl --> Ar-Cl; HBr or CuBr --> Ar-Br; KCN or CuCN --> Ar-CN; KI --> Ar-I; H3PO2 --> Ar-H
Name the three configurations for butyl.
isobutyl - fish tail at the end
sec-butyl - the C attached to the chain used to be secondary
tert-butyl - the C attached to the chain used to be tertiary (cross)
1) Cumene 2) Styrene 3) Anisole
1) Isopropyl Benzene 2) Ph-CH=CH2 3) Ph-)CH3
Epoxide Reaction with Acids: Mechanism and Regioselectivity I
Acids HZ that contain a nucleophile Z also open epoxide rings by a two-step sequence.
HCl, HBr, and HI as well as H2O and ROH in the presence of acid all open an epoxide ring in this manner.
For unsymmetrical epoxides, the major product will result from attack on the more substituted carbon.
Name the two configurations for propyl.
isopropyl - looks like a fish tail at the end of the chain
Propyl - straight carbon chain
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