Top Hat Pre lab and procedure questions

EXP 5: What signals should you pay attention to in the IR spectrum? (select all that apply)

- C-H stretches - C=O stretch

Select the correct statements. You may select more than one answer. - furan is the diene and maleic anhydride the dienophile - furan is the dienophile and maleic anhydride the diene -furan is the electrophile and maleic anhydride the nucleophile - maleic anhydride is electron-rich - maleic anhydride is electron-poor

- furan is the diene and maleic anhydride the dienophile - maleic anhydride is electron-poor

In the IR spectrum of acetone, which of the following signals fall in the fingerprint region? Select all that apply.

1360 cm-1 1211 wavenumbers

This molecule is responsible for the smell of celery. How many units of unsaturation does it contain?

4

What is the product of this oxidation?

A

Which is the correct arrow-pushing mechanism for the reaction shown below?

B

Which of the following statements about spectroscopy are false? A. Spectroscopy is used to gather information about chemical structure B. All spectroscopies require IR radiation C. IR spectroscopy examines the interaction of infrared radiation with matter D. NMR spectroscopy examines the interaction of radio waves with matter E. IR spectroscopy can be used to determine what functional groups are present in molecules

B. All spectroscopies require IR radiation

Which is the correct depiction of the transition state for the reaction shown below?

C

Briefly describe the difference between deuterium (D) and hydrogen (H). What is their relationship?

Deuterium is a isotope of Hydrogen. Deuterium contains one neutron unlike Hydrogen which contains none.

What is the product of this electrophilic addition reaction?

E

What is the product of the reaction between compounds A and B?

F

EXP 6: What is the role of adding NaOH?

It deprotonates hydrogen peroxide and makes it a better nucleophile

What was the purpose of using the KMnO4 stain?

KMnO4 stains are very useful for showing certain functional groups. This includes alkenes, which would show up very bright yellow when using a KMnO4 stain. The purpose of the stain was to be to allow us to more easily see the starting material in the TLC results.

Based on μ(C-H) and μ(C-C) calculated above, which bond exhibits a higher frequency of vibration?

The C-H bond

Markovnikov

The H atom will always bond to the C with more H

Explain why the endo-rule is not obeyed when furan is used as the diene. Use chemical structures and models to support your answer.

The endo-rule is not obeyed when furan is used as the diene because the exo product in this case is more stable and kinetically favorable. The oxygen in furan is electron donating and causes destabilization.

what is the goal of hydrogenating oils?

The goal of hydrogenating oils is to fully saturate all the triacylglycerides

Reflux apparatus

The key component of the reflux apparatus is the reflux condenser, which has an interior design that maximizes surface area. There is a hollow inner layer in which cold water passes through to cool the inner surface of the glass. The cold surface acts to cool and condense liquid vapors so that the solvent doesn't boil away. In Figure 1, The designs range from simple cylindrical (left), to wavy (middle), to a narrowly spaced coil (right); the basic principle is to increase the surface area. Tap water flows through the condenser (from the bottom up) to cool the inner surface. The greater the surface area, the more efficient the cooling.

EXP 4: Hydroboration-Oxidation of Indene Reaction Scheme

The main objective to the experiment was to examine the regioselectivity in the hydroboration oxidation reaction of indene. Below is the reaction scheme showing this.

EXP 2: There are two types of hydrogenations: heterogeneous hydrogenation and homogeneous hydrogenation. What type of hydrogenation does the one you performed fall under and what observation(s) did you make to support your answer?

This experiment is an example of heterogenous hydrogenation. We can tell that it is heterogynous hydrogenation since the starting materials are not miscible with one another, one is liquid, and one is solid. The catalyst (palladium, solid) exists in a phase different than the reactants (liquid).

What is the difference between an air condenser and a water-cooled (reflux) condenser?

an air condenser relies on ambient air whereas a water-cooled condenser requires cool water

EXP 8: In the separatory funnel containing the organic and aqueous layers, which of the following could be dissolved in the aqueous layer?

copper(II) hydroxide

Concerted chemical reaction

do not involve intermediates, potential to form multiple bonds in a single step

Which is the correct mechanism for the reaction between NaOH and H2O2?

e

The alkene is the ____________ and hydrogen peroxide is the ____________

electrophile, nucleophile

EXP 6: What is the purpose of using brine in the final step of the liquid-liquid extraction procedure?

it helps to remove residual water from the organic extract

Which of the following is true about ammonium formate? A. it is explosive B. it is used as a source of hydrogen C. ammonium cation can only dissolve in the aqueous layer and formate anion can only dissolve in the organic layer D. both ammonium and formate donate protons E. both ammonium and formate donate hydrides

it is used as a source of hydrogen

What is the role of Pd/C in experiment 2?

it is used for the hydrogenation process

What is NMR spectroscopy used for?

it uses radio waves to excite nuclear spin, which provides information on chemical structure

How could one distinguish between ketone A and enone B using IR spectroscopy?

ketone A should have a higher C=O stretching frequency than enone B

EXP 4: How could you use IR spectroscopy to determine whether the hydroboration-oxidation reaction is successful?

look for disappearance of a C=C stretch at ~1600 cm-1 and appearance of an O-H stretch at 3200-3400 cm-1

Saturated molecule

maximizes the number of hydrogens on carbons

A chemoselective reaction describes a reaction where

one functional group selectively reacts over another

In which of the following scenarios will it be better to use a water-cooled condenser?

stirring a reaction dissolved in acetonitrile (bp 81-82 °C) at 100 °C

In which situation is it most appropriate to use a reflux condenser? - stirring a reaction in ethanol solvent at 0 °C - stirring a reaction in ethanol solvent at room temperature - stirring a reaction in ethanol solvent at 40 °C - stirring a reaction in ethanol solvent at 80 °C - all of the above

stirring a reaction in ethanol solvent at 80 °C

coupling constant

subtract two middle signals then multiply by the Hz on the chart

The 1H NMR spectrum in Figure 8 shows 3 signals at δ 3.5, 1.8, and 1.0. Each signal has a curve above it. The curves are approximately the same height for signals at δ 3.5 and δ 1.8. What does that mean?

the signals at δ 3.5 and δ 1.8 both represent the same # of protons

EXP 7 : what is the purpose of the air condenser?

to prevent acetic acid from evaporating

EXP 5: What is the purpose of using the rotary evaporator in this experiment?

to remove furan and maleic anhydride

In the second step of the acid-catalyzed hydration (see image), which of the following statements about nucleophiles and electrophiles is correct?

water is the nucleophile and the carbocation intermediate is the electrophile