Chem 232L Final

The limiting reagent in a chemical reaction is the reagent that

is completely used up in the reaction

Which of the following is/are use(s) of thin layer chromatography?

to determine the identity of two substances & to determine the number of compounds in a mixture

which of the following is NOT flammable?

Dichloromethane

An esterification is a reaction that takes place between which two functional groups?

carboxylic acid and alcohol

The Diels Alder is a [4 + 2] concerted reaction. What does this mean?

it is a stimulus process involving 4 electrons of one reactive, and 2 electrons of the other

Grignard and Barbier reactions are useful because of their ability to create which type of bond?

C-C

In the Electrophilic Aromatic Substitution of

Salicylamide sodium iodide and sodium hypochlorite were used to generate the electrophile for the reaction. What is the actual structure of the electrophile?

I2

A distillation is a technique that can be used to separate compounds based on

boiling point

What effect would the addition of too much solvent have on the percent recovery of a recrystallization?

Decrease it

Which of the following statements is NOT true about a vacuum distillation?

you should begin heating your sample before putting the system under vacuum

Which of the following reagents is NOT an oxidizing agent?

LiAlH4

A secondary alcohol can be oxidized in the presence of a primary alcohol.

True

The TLC plate below was obtained by spotting the products of the three dihydroxylation reactions performed in lab, using Oxone, potassium permanganate or the Woodward reagents (2, AgOAc). The student performing the experiment recorded the following legend for the TLC plate below:

The trans diol has a smaller Rf value than the cis

Identify A and B in the diagram on the right

A = water out; B = water in

The nucleophile in the aldol reaction is a(n)

enolate

Use the IR spectrum shown below to identify the functional group present in the molecule.

Carboxylic Acid

An organic solution contains a mixture of compound A and B (shown below). You put this solution into a separatory funnel with 1M HCI, shake and allow the layers to separate. Where will each compound be?

Compound A is in the organic layer and Compound B is in the aqueous layer.

A solid melts when enough energy is applied to the compound to break bonds.

False

Ten grams of an organic solid are dissolved in

100 mL of water. Which of the following extraction methods will remove the largest amount of the organic solid from the aqueous solution?

three 50ml portion extractions with ether

1. Magnesium sulfate can be used to

1. remove water
   break up an emulsion

Benzoic acid is considered to be a polar molecule.
Which one of the following solvents will completely dissolve benzoic acid at room temperature?

95% ethanol/water

Several compounds are present in a sample which is developed on a TLC plate. Which statement best describes the location of the spots?

more polar compounds toward the top of the plate and less polar ones toward the bottom

The Diels Alder reaction is stereospecific with low atom economy.

False

Which of the following reagents is NOT used to oxidize alkenes?

NaBH4

Which of the following would NOT be a suitable solvent for Grignard reagents?

Ethanol

Increasing the polarity of the developing solvent in TLC would have what effect on the R, value of an alcohol?

increase the Rf value

The set up shown below will accomplish which technique?

distillation

Identify the benzylic position in the molecule shown below.

A

The ideal solvent for the recrystallization of a particular compound is one that

does not react with the compound boils at a temperature below the compound's melting point

In an extraction, a halogenated organic solvent is likely to be the top layer in the separatory funnel.

False

Salicylamide was used as the starting material in the Electrophilic Substitution of Salicylamide. The IR spectrum of salicylamide is shown below. What part of the molecule is responsible for the peak at 1674

ст?

The carbonyl group

Which of the following would NOT be used to purify a compound?

reflux

Which of the following procedures would lead to aldol addition, rather than aldol condensation?

using a catalytic amount of NazCO, then reacting at room temperature

In order for the reaction of hypochlorite and an alcohol to go to completion, the hypochlorite must be in excess during the reaction. The presence of excess hypochlorite must be established by which test?

iodine-starch

Which compound below will be colored?

B only

If a compound contains an impurity, its melting point range is

and

than its

literature value.

broader; lower

1. A Diels Alder reaction readily occurs if the diene is in the _____ orientation.

s-cis

When using a drying agent to dry an organic compound, the solution is dry when

the drying agent stops clumping together and some begins to float freely.

A minimal amount of cold solvent should be used to dissolve your solid in a recrystallization.

False

If equal volumes of hexane and water are added to a separatory funnel, which layer would be on the top?

Hexane

Which of the following compounds is the most highly oxidized?

ROOH

The following information pertains to questions 42-44:

Methyl salicylate may be synthesized in a trans-esterification reaction where acetylsalicylic acid is reacted with methanol using sulfuric acid as a catalyst.

42) The 'H NMR spectrum below represents which one of the compounds in the above reaction?

acetylsalicylic acid

43) Which proton(s) in the compound is/are responsible for the signal at 11 ppm in the 'HNMR spectrum above?

carboxylic acid

44) The ring substituents in the above equation are in which position?

ortho

After recrystallization in water you did not allow your crystals to dry thoroughly. Which of the following will NOT be affected?

TLC

Boiling chips or stir bars are used in a distillation pot to

prevent bumping of the solution caused by overheating

Acetone is considered to be a polar solvent because

there is a large dipole moment associated with the
C=0 bond

What is the dienophile in the Diels Alder reaction of

1,3-cyclohexadiene and 3-butene-2-one?

3-butene-2-one

Which TLC plate is most consistent with compound A having a Rf value of 0.25 and compound B having a Rf value of 0.75.

C

The Fischer esterification and the aldol reaction are equilibrium reactions that obey

Le Chatelier's Principle