CHEM 242 Final

See lecture slides for answer Anthranilic Acid

Do arrow pushing for the following: And name the acid on the right

Water, alcohol, acids

During the Ester lab's extraction, what would make up the bottom layers throughout the whole extraction?

Oiling out creates a separate solvent layer that traps impurities rather than the impurities going to ethanol. This happens because of the benzil being too warm to freeze into a crystal solid.

During the first step of converting benzoin to benzil for the three step synthesis, why is it a problem if benzil "oils out" (melting) instead of it dissolving in ethanol during crystallization?

When the possible derivatives have very close melting points, but very different molecular weights.

For derivatives, when would you do a titration and why?

- Aldehydes - Ketones - Esters - 4 + Carbon Alcohols

For solubility, what compound types are insoluble in water at any pH?

- Carboxylic acids - Strong acids

For solubility, what compound types are soluble in basic water (NaOH and NaHCO3)?

- Amines

For solubility, what compound types are soluble in strong acidic water (HCl)?

- Phenols - Weak acids

For solubility, what compound types are soluble in strong basic water (NaOH)?

We did this to monitor the conversion of benzoin to benzil by comparing the reaction mix dot to a benzoin standard dot and benzil standard dot.

For the first step oxidation of the three step synthesis, why was it necessary to run a TLC plate in the middle of the reaction and at the end of the reaction?

Endo

For the reduction of camphor lab, hydride attacking from the bottom is what kind of attack?

Exo

For the reduction of camphor lab, hydride attacking from the top is what kind of attack?

Flammable hydrogen gas

For the reduction of camphor lab, what is produced if NaBH4 is reacted with water?

H- (h minus)

For the reduction of camphor lab, what is the nucleophile that attacks the carbonyl?

Diastereomers

For the reduction of camphor lab, what is the relationship between the two products?

Camphor (lowest mp), isoborneol (first of the coeluted peak of isoborneol and borneo), then borneol

For the reduction of camphor lab, what order does camphor, borneol, and isoborneol elute on GC? (rank by shortest retention time to longest retention time)

LiAlH4

For the reduction of camphor lab, what other reducing agent could you use?

Endo because there is less steric hinderance with this attack. Exo attack makes hydride have a steric clash with the methyl groups on the top.

For the reduction of camphor lab, which hydride attack is favored and why?

Hydride (h-) getting oxidized into H2 after it attacks the carbonyl, loosing its negative charge.

For the reduction of camphor lab, which is the oxidizing step??

The isoborneol, which has an equatorial OH group from the endo attack of hydride. Isoborneol is more favored because there is less steric hinderance with this type of endo attack. Exo attack makes hydride have a steric clash with the methyl groups on the top.

For the reduction of camphor lab, which isomer product is favored and why?

Sodium Borohydride

For the reduction of camphor lab, which reagent is reducing camphor?

Sodium Borohydride (NaBh4) would react with water instead of the ketone. Camphor is also not water soluble.

For the reduction of camphor lab, why wouldn't we be able to use water as a solvent for the reduction step?

- CH as Nuc with a neg charge on it (must be on alpha carbon next to carbonyl) - Carbon of the carbonyl on benzil

For the second step, aldol condensation, of the three step synthesis, what is acting as the nucleophile? What is being attacked?

8 drops (math in lab notebook)

For the third step of the three step synthesis lab, calculate the required volume of isopentyl nitrite (in drops) if the experiment starts with 100 mg of tetraphenylcyclopentadieneone. Since "drops" are a quantized value, they should berounded to a whole number. *Tetraphenylcyclopentadienone (amount from step 2) *Anthranilic acid (1.25 molar equivalents) *1,2-dimethoxyethane for the above two reactants (12 mL per gram of tetraphenylcyclopentadienone) *Isopentyl nitrite [density: 0.872 g/mL, 75 drops/mL] (2.0 molar equivalents) *1,2-dimethoxyethane for the isopentyl nitrite (5 mL per gram of tetraphenylcyclopentadienone

Answer in lecture notes

For the third step of the three step synthesis, draw an arrow pushing mechanism for the following Be sure to draw product before the elimination of C-O

- Answer in lecture slides - Reaction relieves ring strain - CO by product

For the third step of the three step synthesis, draw an arrow pushing mechanism for the following: Don't forget to add by products. Why does this reaction occur?

-Risk of over heating possible due to it being an exothermic reaction. - Excess vapors produced of isopentyl nitrite would have serious health consequences since it's a vasodilator

For the third step of the three step synthesis, why is isopentyl nitrite added slowly rather than all at once?

0.22 g diphenyl acetone (look at submitted pre lab 2 for lab 2 for the math)

For the three step synthesis lab, In the second step of the synthesis, the procedure in the manual calls for 1 (molar) equivalent of diphenylacetone relative to the amount of benzil that you made in step 1 (i.e. 1 mole of diphenylacetone for every 1 mole of benzil). If you synthesized 0.22 g of benzil in the first step, how many grams of diphenylacetone will you need in the second step? (*Benzil (amountfrom step 1) *1,3-diphenylacetone (1.0 molar equivalent) *Absolute ethanol-200 proof (8 mL per gram of benzil) *Potassium hydroxide solution in ethanol [density:70 drops/mL, 0.1g KOH/mL solution] (0.5 molar equivalents)

14 drops (look in lab notebook for the math)

For the three step synthesis lab, the second step, Calculate how many drops of the potassium hydroxide solution (0.1 g/mL potassium hydroxide in absolute ethanol; 70 drops/mL) would be needed to add 0.5 equivalents of ethanolic potassium hydroxide to the reaction mixture from question 1. Since "drops" are a quantized value, they should be rounded to awhole number. (*Benzil (amountfrom step 1) *1,3-diphenylacetone (1.0 molar equivalent) *Absolute ethanol-200 proof (8 mL per gram of benzil) *Potassium hydroxide solution in ethanol [density:70 drops/mL, 0.1g KOH/mL solution] (0.5 molar equivalents)

A and B

For the three step synthesis, Why does the reaction only need 0.5 equiv. of KOH even though 2 consecutive aldol condensations are occurring? a.) KOH is catalytic in stage one- after it is used to make the enolate during the addition stage it is regenerated when the alkoxide is promoted b.) KOH is catalytic in stage two- once it is used to make the enolate during the dehydration stage, it is regenerated when the hydroxide is a leaving group c.) 2 equiv are needed but in the interest of safety we are willing to accept a reduced yield. d.) 2 equiv. are needed but we only need a "low" yield of 100 mg in order to move on to the next step.

A: Diazonium salt (draw structure) B: Benzyne

For the three step synthesis, fill in the following:

- Benzil (two carbonyls) - Benzoin (one carbonyl and one alcohol) - HNO3

For the three step synthesis, what is the product of the first step oxidation? What is the starting material? What reagents are used?

- Tollen's - Lucas Reagent - DNP

For the unknowns lab, which reagents had separate waste containers?

We would not be able to tell which peaks belonged to the alcohol and which belonged to the ester besides the wide O-H peak if it were to be present due to the overlap of peaks/similarity.

How would you be able to distinguish an alcohol and an ester 50:50 mix using HNMR

Do the Tollen's test

How would you test to tell the difference between an aldehyde and a ketone?

- Use either alcohol or acid in excess (whichever is cheaper) and in lab we used acetic acid in excess. - Le-Chatelier's principle states that if a reactants or products are changed in any way, the equilibrium will shift to adjust to that change. In lab, by using acetic acid in excess, this pushed the equilibrium to the right to favor the products due to this principle.

In order to get more ester product, how was that done in the fischer esterification lab? Why does this work?

Very strong acid, like H2SO4 that we used in lab in order to protonate the carbonyl oxygen to start the reaction. ACIDIC AHOLE

In regards of the esters lab, since carboxylic acids are very weak bases (not likely to be protonated, would rather be deprotonated. Wants to not hang on to H's), what do we need in order to start the acid-catalyzed esterification?

No

Is this fully aromatic

Yes

Is this fully aromatic

Yes

Is this fully aromatic?

1:1

On a MS, bromine has a ____ to ______ ratio of M and M+2 peak

3:1

On a MS, chlorine has a ____ to ______ ratio of M and M+2 peak

Green flame due to the metal having a copper salt from a halogen

The Beilstein test is positive when? Why?

An imine

The product of a DNP positive test is a?

FALSE!!! The equilibrium favors BOTH the products and reactants evenly. (the carboxylic acid and ester)

True or False: acid-catalyzed esterification's equilibrium usually favors the products over the reactants.

True

True or false: small esters tend to have pleasant smells

A

What IR changes would we see as a mixture of acetic acid and butanol becomes butyl acetate and water? a.) The C-O peak at 1700 would shift to a new location b.) The C-O peak at around 1200 would appear c.) O-H peak at around 3300 would disappear d.) C-O peak at around 1700 would disappear

A

What IR changes would we see as a mixture of acetic acid and butanol becomes butyl acetate and water? a.) The C=O peak around 1700 would shift to a new location b.) C-O peak around 1200 would appear c.) O-H peak around 3300 would disappear d.) C=O at 1700 would disappear

Unsaturation in a compound, which causes the sooty flame due to less H2O than CO2.

What creates a sooty flame for the Ignition test?

2C + 2 + N - X - H all over 2

What is the degrees of unsaturation equation for NMR problems?

-Nitric acid: oxidizer, corrosive, if not disposed of in proper separate waste container an explosion could occur, nitrogen oxide gases produced that are harmful during reaction. - Denatured 95% ethanol: flammable and toxic because of it being denatured - Hot and cold aluminum blocks look identical take caution

What is the reagent(s) with the most risk in regards of safety used in the first step of the three step synthesis? (Oxidation of benzoin step) What are some other safety concerns?

- KOH: corrosive bc of it being a strong base - 95% Ethanol: denatured (makes it toxic) and flammable - Heating: so hot plates, hot glass ware, and hot metal all look identical to cold so take caution

What is the reagent(s) with the most risk in regards of safety used in the second step of the three step synthesis? (aldol condensation) What are some other safety concerns?

- Isopentyl nitrite (poppers drug): releases nitric oxide in blood (lowered bp, increased heart rate, dizziness. Must transport in capped vial and keep hood sash as low as possible while working and closed when not working. - 1,2-dimethoxyethane is flammable - Heating: hot metal, glassware, plates - Carbon monoxide by-products: highly toxic gas

What is the reagent(s) with the most risk in regards of safety used in the third step of the three step synthesis? (benzyne formation, diels alder, elimination ) What are some other safety concerns?

- Positive test for Aldehydes and ketones - False negatives: Esters, carboxylic acids, amides because they are reacted to turn into amides, which give a negative

What kinds of functional groups does the DNP test test for? What kinds of functional groups give a false negative and why?

Benzil + 1,2-diphenylacetone ----> Tetraphenylcylcopentyldienone use of KOH in EtOH as reagent.

What reagents are used for the second step (aldol condensation) of the three step synthesis?

Creates a convection current that allows for air flow to be as accurate as possible, will get accurate reading

When taking the boiling point, why is it important to heat the side of the Thiele tube?

- H20: ester would be in organic layer and on top. H2O removes remaining H2SO4, H2O, acetic acid and the unknown alcohol - NaHCO3: ester would be in organic layer and on top. NaHCO3 neutralizes any remaining acid left in ester layer from before - NaCl: ester would be in organic layer and on top. Removes additional water from the ester layer from the previous extraction

When washing your ester in a sep funnel with the following, where would your ester end up (top or bottom layer/ organic or aqueous layer) and what is the function of the solvent being used to wash? - H2O - NaHCO3 - NaCl

F. Carboxylic Acid

Which four functional groups (a. Alcohol, b. Phenol, c. Ketone, d. Aldehyde, e. Ester, f. Carboxylic Acid, g. Amine) can be uniquely identified based on the C=O and O-H regions of the IR spectrum?

Benzil: non polar compound with little dipoles in molecule on a polar silica gel TLC plate. Opposites attract, allowing for benzil to travel further up the plate than the polar benzoin, which sticks to the plate.

Which has a larger Rf value, benzoin or benzil? Why?

A,B, and C

Which of the following are soluble in aq. NaOH

D Sulfuric acid is the catalyst, so it won't change equilibrium. It would only change the amount of time for the reaction would take. Can't go at a higher temp than the boiling point, would only hurt the reaction.

Which of the following would increase the product ester/reactant alcohol ratio in the Esters Lab? a.) Running the reaction for longer b.) Using a larger amount of sulfuric acid c.) Running the reaction at a higher temp d.) None of the above would change the ratio of ester to alcohol.

B

Why are carboxylic acid derivatives sometimes tricky? A.) The acidity of the carboxylic acid group reacts with the solvent B.) The thionyl chloride is prone to decomposing before the acid chloride can be made C.) The basic amine reacts with the acidic carboxylic acid to form an unreactive ammonium carboxylate salt D.) Carboxylic acids are inherently less reactive than other functional groups like esters

Deuterated solvents are "invisible" in an 1H NMR spectrum while non-deuterated solvents will obscure important peaks

Why are deuterated solvents used for NMR?

Methylene chloride's peak shows up in the finger print region of the IR, which doesn't affect any major indication peaks while using an alcohol would give a large OH peak.

Why is it appropriate to create an IR sample with methylene chloride? Why not use an alcohol?

B

Why is it necessary to rinse the alcohol with acetic acid for the Esters Lab? a.) To ensure that excess acetic acid is used to drive the equilibrium b.) The alcohol is the limiting reagent so it's important that all of the alcohol makes it in to the reaction flask c.) The graduated cylinder needs to be cleaned before the end of lab

D

Why is the Lucas test ambiguous for large alcohols? a.) Larger alkyl chlorides are more water soluble than smaller ones, so no precipitate forms b.) Large alcohols undergo substitution reactions slower than small alcohols due to sterics, no product forms c.) Large alcohols have a higher molecular weight, so less alkyl chloride is produced and harder to see d.) Larger alcohols are less water soluble than small alcohols, any precipitate is unreacted alcohol

Looking at the total molecular weight and if it's an odd number.

You are able to tell if a nitrogen is present in a compound by looking at the what on a MS?