O Chem 2 Lab Final Flashcards
What does sodium hypochlorite do to the secondary alcohol in the oxidation of an unknown alcohol lab?
It turns the alcohol into a ketone
What is sodium hypochlorite in the oxidation of an unknown alcohol?
Oxidizing Agent
How was excess hypochlorite tested for in the oxidation of an unknown alcohol lab?
KI-starch paper
What indicated an excess of hypochlorite in the oxidation of an unknown alcohol lab?
The starch paper turned blue
(If the paper remained white, add NaOCl until paper turned blue)
What was used as a reducing agent in the oxidation of an unknown alcohol lab?
Sodium bisulfite
What was the role of sodium bisulfite in the oxidation of an unknown alcohol lab?
Used to quench excess hypochlorite remaining after the reaction has gone to completion
(Checking KI-starch paper to make sure it remained white)
What does quenching mean?
Forcing any residual oxidizer to react, stopping the reaction
What was used to achieve a basic solution in the oxidation of an unknown alcohol lab?
6M sodium hydroxide
What did the base do in the oxidation of an unknown alcohol lab?
Neutralized the residual acetic acid (forming acetate) allowing it to be water soluble while the product remained un-ionized
What type of extraction was used in the oxidation of an unknown alcohol lab?
Liquid/liquid
What was used to extract the product into the organic layer (bottom layer) in the oxidation of an unknown alcohol lab?
Methylene chloride
What method is used for liquid/liquid extraction?
Separatory funnel
What is used for the drying agent and how is it removed?
Magnesium sulfate (MgSO4) removed by gravity filtration
How is solvent often removed at the end of the experiment?
Using a rotary evaporator or hot plate/ snorkel
What conversion should occur in the IR stretches in the oxidation of an unknown alcohol lab?
O-H stretch to C-O double bond stretch
What is the solvent in the oxidation of an unknown alcohol lab?
Acetic Acid (CH3CO2H)
What happened in the conversion of carvone to carvacrol lab?
The carvone reaction converted a chiral compound to an achiral compound through an acid-catalyzed elimination
What is the catalyst/solvent in the conversion of carvone to carvacrol lab?
6M H2SO4
What is this reagent?
(R)-(-) Carvone
What is this product?
Carvacrol
What was used to run the reaction in the conversion of carvone to carvacrol lab?
Reflux
What is significant about reflux?
It is a boiling point reaction without losing solvent
What type of extraction was used in the conversion of carvone to carvacrol lab?
liquid/liquid
What was the product extracted into in the conversion of carvone to carvacrol lab?
Diethyl ether
What was the ether extract used for in the conversion of carvone to carvacrol lab and why was it used?
Sodium Bicarbonate used to neutralize the acid
What was used to dry the product in the conversion of carvone to carvacrol lab?
Sodium sulfate (Na2SO4)
What peaks were changed in the IR of the conversion of carvone to carvacrol lab?
C-O double bond carbonyl changed for O-H stretch and arena peak/undertones
What is used to form an ether in Williamson-Ether synthesis?
An alcohol and alkyl halide under basic conditions
Why are primary alkyl halides typically used for Williamson Ether Synthesis?
The alkyl halide serves as the electrophile for an Sn2 reaction
What type of alkyl halide was used in the Williamson-Ether Synthesis lab?
Unknown primary Alkyl Bromide
What were the catalysts used in the Williamson-Ether Synthesis lab?
KOH (base catalyst) & TBAB (phase-transfer catalyst)
What does TBAB stand for in the Williamson-Ether Synthesis lab?
Tetra-N-butylammonium bromide
What does TBAB do in the Williamson-Ether Synthesis lab?
Phase transfer catalyst that works by helping ions cross between the organic and aqueous phase
What was used to run the reaction in the Williamson-Ether Synthesis lab and why?
Microwave reflux to speed up the reaction by holding the reaction at a constant temperature and pressure
What isolation method was used in the Williamson-Ether Synthesis lab?
Liquid/liquid extraction
What was used to extract the mixture in the Williamson-Ether Synthesis lab?
diethyl ether
What layer was the product in the Williamson-Ether Synthesis lab?
organic layer / washed with potassium hydroxide to remove impurities
What was used as the drying agent in the Williamson-Ether Synthesis lab?
sodium sulfate
What was used to purify the product in the Williamson-Ether Synthesis lab?
column chromatography to separate components of a mixture on a milligram-to-milligram scale
What is the mobile phase of the column chromatography in the Williamson-Ether Synthesis lab?
Methylene Chloride (DCM) (less polar)
What is the stationary phase of column chromatography in the Williamson-Ether Synthesis lab?
Silica gel (more polar)
What phase did the product remain in the Williamson-Ether Synthesis lab and why?
mobile phase because it is less polar than the highly polar stationary phase
What stretch transition was seen in the Williamson-Ether Synthesis lab?
O-H stretch to C-O-C stretch
What was used for characterization in the Williamson-Ether Synthesis lab?
Thin Layer Chromatography (TLC) used to check product formation and product purity
What were the 3 spots on the TLC plate in the Williamson-Ether Synthesis lab?
4-bromophenol, unknown alkyl halide, and purified product
What was the stationary phase of TLC in the Williamson-Ether Synthesis lab?
silica gel (polar) –> polar compounds bind to the silica gel and do not migrate to top of plate
What was the mobile phase of TLC in the Williamson-Ether Synthesis lab?
methylene chloride (less polar) –> less polar compounds remain in the mobile phase and migrate to the top of the plate with the solvent front
How do you calculate Retention factor?
Rf = distance from origin to spot / distance from origin to solvent front
What side does the nucleophile attack on an epoxide in acidic conditions?
Most substituted
What side does the nucleophile attack on an epoxide in basic conditions?
Least substituted
Why was ammonium chloride used in the basic workup in the acid v base nucleophilic ring-opening of 1,2 epoxygexane lab?
To avoid ether cleavage (ethers cleave in strongly acidic conditions)
What are the acidic reagents in the acid v base nucleophilic ring-opening of 1,2 epoxyexane lab?
H2SO4 & methanol
What are the basic reagents in the acid v base nucleophilic ring-opening of 1,2 epoxyhexane lab?
- NaOCH3, methanol
- NH4Cl
What was used to run the reaction in the acid v base nucleophilic ring-opening of 1,2 epoxyhexane lab?
Reflux
What isolation method was used in the acid v base nucleophilic ring-opening of 1,2 epoxyhexane lab?
liquid/liquid extraction
What was used to wash the reaction mixture in the acidic conditions in the acid v base nucleophilic ring-opening of 1,2 epoxyhexane lab?
Saturated sodium bicarbonate solution to neutralize the acid
What was the product extracted from and into in the acid v base nucleophilic ring-opening of 1,2 epoxyhexane lab?
from the aqueous layer into diethyl ether
How was the drying agent removed in the acid v base nucleophilic ring-opening of 1,2 epoxygexane lab?
Decanting
What was used to wash the reaction mixture in the basic conditions in the acid v base nucleophilic ring-opening of 1,2 epoxygexane lab?
Saturated ammonium chloride to neutralize the base in solution
What drying agent was used in the acid v base nucleophilic ring-opening of 1,2 epoxygexane lab?
magnesium sulfate
What was used to characterize the product in the acid v base nucleophilic ring-opening of 1,2 epoxygexane lab?
Gas chromatography
How are mixtures separated in gas chromatography?
Based on each components affinity for the non-polar stationary phase versus the inert gas mobile phase (each component will exit column at different times)
What equation is used to ration peaks in gas chromatography?
% P = (A1/ (A1 + A2 + A3)) * 100
What compounds have longer retention times in the acid v base nucleophilic ring-opening of 1,2 epoxygexane lab?
polar
How are esters generally synthesized under Fisher conditions?
From a carboxylic acid and an alcohol under acidic conditions
According the Le Chatlier’s principle, what will drive the reaction toward the products?
Increase concentration of alcohol or remove water as it is formed
All Fisher esterification reactions proceed via _____
microscope reversibility (the forward and reverse pathways in the mechanism are identical)
What was used for basification in the Fischer Esterification lab to neutralize the organic layer and what does it result in?
Sodium Bicarbonate (NaHCO3), resulting in the formation of CO2 which bubbled out of solution
What was used as the drying agent in the Fischer Esterification lab?
Sodium sulfate
Why are acid halides not able to be used for amide synthesis?
They are moisture sensitive and not fit for moisture rich environments
What is the catalyst in the amide synthesis lab?
Aluminum oxide (Al2O3)
Why is aluminum oxide used in the amide synthesis lab?
Allows for admiration of a carboxylic acid in high yields without having to use an acid halide
What type of extraction was used in the amide synthesis lab?
solid/liquid extraction
What was used to extract the product from the reaction mixture in the amide synthesis lab??
Ethyl acetate
Why is ethyl acetate used in the amide synthesis lab?
The unknown amine and aluminum oxide are not soluble in ethyl acetate; only the product goes into ethyl acetate
What was used to separate the ethyl acetate from precipitate in the amide synthesis lab?
gravity filtration
What was used to identify the final product in the amide synthesis lab?
Melting point determination
What is sodium borohydride used to reduce?
aldehydes, ketones, acyl halides, thiol esters, and imines
will NOT reduce esters, amides, or carboxylic acids
What was the reducing reagent used in the reaction of an unknown ketone/aldehyde lab?
sodium borohydride (NaBH4)
What was used to run the reaction in the reaction of an unknown ketone/aldehyde lab?
reflux
What method of extraction was used in the reaction of an unknown ketone/aldehyde lab?
liquid/liquid extraction
What was used to extract the mixture from the aqueous layer in the reaction of an unknown ketone/aldehyde lab?
methylene chloride (goes to bottom)
What happens in the Wittig reaction?
Forms a double bond via reaction of a phosphorus ylide with an aldehyde or ketone
What is the by product of the witting reaction?
O double bond PPh3
What is added dropwise into the reaction in the wittig reaction lab?
sodium hydroxide resulting in formation of ylide
The aldehyde is ___ and the ylide is ____ in the wittig reaction lab?
hydrophobic/ hydrophilic
What was used as the drying agent in the wittig reaction lab?
Calcium Chloride
What was the product purified from using recrystallization in the wittig reaction lab?
1-propanol
Why is the product favored in the aldol condensation lab?
Due to conjugation throughout the molecule
What was added dropwise to the stirring solution of aldehyde and ketone
sodium hydroxide
What formed in the reaction vile during the aldol condensation lab?
white/yellow precipitate
What helped with crystallization in the aldol condensation lab?
ice bath
How were the crystals collected in the aldol condensation lab?
suction filtration
What were the crystals washed with in the aldol condensation lab?
DI water to neutralize residual sodium hydroxide
What was the product purified using recrystallization from in the aldol condensation lab?
ethanol
How were the crystals collected in the aldol condensation lab?
suction filtration
When do EAS reactions proceed quickly?
When strongly electron donating groups are attached to the ring
What was the electrophile formed from in the Friedel-Crafts Alkylation lab?
tertiary alcohol and a Bronsted acid catalyst
What was the catalyst in the Friedel-Crafts Alkylation lab?
sulfuric acid
The electrophile was generated ____ (in the reaction mixture) in the Friedel-Crafts Alkylation lab?
in situ
What happens after the electrophile is added in the Friedel-Crafts Alkylation lab?
benzene undergoes E1 elimination to reform aromaticity
How was the reaction quenched in the Friedel-Crafts Alkylation lab?
Addition of ice cold water to the reaction mixture (neutralizing acid catalyst)
What formed from the quenching of the reaction in the Friedel-Crafts Alkylation lab?
white precipitate
