Experiment Quizzes

Why are alpha hydrogens more acidic than the other hydrogens in the carbonyl compounds?

Because of the induction due to the partial pos/neg charge in carbonyl and because it cannot be stabilized by resonance to the enolate anion

True or False: Aldol reaction is an example of C-C bonds formation reactions

True

Give the criteria for selecting a recrystallization solvent:

If it is too soluble, use a less polar solvent

Why are ketones less reactive than the aldehydes?

Carbonyl group in ketones has steric hindrance and is less electrophilic than in aldehydes due to the presence of two alkyl groups. It is also not as susceptible to nucleophilic attack

State one commercial application of Aldol condensation reaction

Rivatin, the prescription given to people with ADHD is a widely used medication that includes products derived from aldol condensation reactions.

Under what conditions do you heat the reaction mixture in a water bath at 80C for 10-15 minutes? (expt 13)

Basic conditions

List 2 apparatus we used in experiment 13:

Herch funnel for vacuum filtration and IR spectrum

In a Fischer reaction, a carboxylic acid is exposed to an alcohol and a strong acid catalyst that in turn yields ____ and ____ as the reaction products

ester and h2o

Why do we carry out reflux in experiment 11?

To ensure the reaction occurs at a constant temperature without loss of volatile components.

T/F: Fischer esterification is a reversible reaction

True

T/F: It is necessary to empty the Hickman stillhead during distillation (expt 11)

False

T/F: A recrystallization is likely to be necessary to obtain an accurate melting point

True

T/F: Glacial acetic acid is anhydrous acetic acid

True

What practical approach can you take to obtain good yields of ester?

Remove H2O and add excess acid

The layer that contains ester in expt 11 is

the organic layer

why should we use dry glassware in expt 11?

because the addition of water can result in the formation of carboxylic acid

Which of the following statements about Fischer esterification are FALSE:

a) a strong acid catalyst is used

b) the reaction exploits Le Chateliers principle to maximize product yield

c) Excess ROH forces the reaction to completion

C

What was the purpose of experiment 8 (Diels Alder rxn)

To conduct a Diels Alder Reaction between maleic anhydride and 2,3-butadiene. Then we hydrolized and did melting point and IR to compare

T/F: Diels Alder reaction is considered to be stepwise

False

T/F: A concerted (2+2) cycloaddition reaction is thermally allowed according to Woodward and Hoffmann

False

T/F: Experiment 8 (Diels Alder) is a (4+2) cycloaddition

True

Why is Diels Alder rxn stereospecific? what temperature do we maintain during the reaction?

Because the bonds will break and form all at the same time, leaving no room for the bonds to move. We’ll maintain the temperature at 60-70C

In experiment 8, how you remove cloudiness when hexane is added to the rxn mixture?

By applying heat

What is the catalyst used to hydrolize the cyclic anhydride to diacid in experiment 8

HCl

why do we have to control the temperature of the water bath in exp 8

To ensure that the diene stays in the mixture and not evaporate

____ are made up of smaller molecules called monomers

Polymers

T/F: Styrene has a very strong odor so it must be carried out in the hood to minimize exposure

True

T/F: All solid and liquid waste generated during this experiment should be discarded in the appropriate waste container

True

T/F: The bonds in the cross links between the borate ion and alcohol functional group of PVA are very strong

False

How many polymers are made in expt 7

Three

Why are we using a diacid chloride rather than the dicarboxylic acid for the preparation of Nylon-10,6?

Because it is more reactive than the dicarboxylic acid, leading to a more efficient polymerization process.

The polymerization to make polystyrene involves the use of a radical initiator to start the polymerization reaction of styrene. What is the name of the initiator?

Benzoyl peroxide

In the preparation of Nylon-10,6 using an acid halide, a small amount of ____ is added to neutralize HCl produced

NaOH

What type of polymerization involve the addition of heat in expt 7?

Chain addition

Match the polymer

Polystyrene - radical polymerization

nylon - condensation polymerization

slime - cross linking

The product of Experiment 12 (amide synthesis) is ether soluble or insoluble?

soluble

Why do we use a 3-1 stoichiometry of amine in the reaction mixture during amide bond formation?

Because amine is added to the reaction and neutralizes HCl produced during the acyl chloride formation

What are two side products in expt 12 (amide synthesis)

HCl and SO2

Why is damp wool (drying tube) used in expt 12 (amide synthesis)

Damp wool in the drying tube prevents moisture from entering the reaction mixture while allowing gases to escape, ensuring a controlled atmosphere for the amide synthesis.

The reaction will ____ upon addition of the mixture of amine and anhydrous ether

smoke

Anhydrous sodium sulphate is used as a _____ in expt 12 (amide synthesis)

drying agent to remove moisture

T/F: I will add the excess thionyl chloride into the flask without my TAs consent in expt 12

False

T/F: Amide synthesis is classified as an exothermic reaction

True

T/F: Another name for N,N-diethyl m-toluamide is DEET

True

T/F: The desired product, N,N-diethyl m-toluamide is soluble in ether

True, as DEET is known to be soluble in organic solvents like ether.

What was the major peak in the IR spectrum of the amide synthesis experiment?

the carbonyl group peak (1600-1800cm^-1)

The general formula for Grignard reagent is

R-X + Mg → R-X-MgX

Why is it important to have your starting material scrupulously dry for preparing Grignard reagents?

It is crucial to have the starting material dry because Grignard reagents react violently with moisture. If there is moisture, it will not start the reaction

What are the possible by products that can be formed in the synthesis of benzoic acid?

Benzene and biphenyl

Why do we need calcium chloride in the Grignard rxn

To protect our reaction from the atmosphere

How do you know the reaction has started? What action would you take to initiate the Grignard rxn if heating alone does not?

I will know if I see a few bubbles and it starts taking a brown/greyish color.

If heating does not work then I remove the claisen head and crush the metal, and if that doesnt work then add Iodine crystals

T/F: Ether is extremely flammable

True

T/F: The grignard rxn is endothermic

False it is exothermic

T/F: Ether is soluble in water at 7% by mass

True

How can you purify the crystals in the grignard reaction?

By dissolving them in a hot water bath