The ¹H NMR chemical shifts of nitromethane, dinitromethane, and trinitromethane are at δ6.10, δ4.33, and δ7.52. Match each chemical shift with the compound. Explain how chemical shift correlates with pK_a.

Which of the following compounds decarboxylates when heated?

Draw the products of the following reactions:

d. diethyl 1,2-benzenedicarboxylate + sodium ethoxide: (1) slow addition of ethyl acetate; (2) HCl

Draw the products of the following reactions:

a.

Draw the products of the following reactions:

b.

An aldol addition can be catalyzed by acids as well as by bases. Propose a mechanism for the acid-catalyzed aldol addition of propanal.

In the presence of excess base and excess halogen, a methyl ketone is converted to a carboxylate ion. The reaction is known as the haloform reaction because one of the products is haloform (chloroform, bromoform, or iodoform). Before spectroscopy became a routine analytical tool, the haloform reaction served as a test for methyl ketones: the formation of iodoform, a bright yellow compound, signaled that a methyl ketone was present. Why do only methyl ketones form a haloform?

Identify A–C. (Hint: A shows three singlets in its 1H NMR spectrum with integral ratios 3 : 2 : 3 and gives a positive iodoform test; see Problem 58.)

Using cyclopentanone as the reactant, show the product of a. acid-catalyzed keto–enol interconversion.

Using cyclopentanone as the reactant, show the product of

b. an aldol addition. 

c. an aldol condensation.

Show how 4-methyl-3-hexanol can be synthesized from 3-pentanone.

Show how the following compound can be synthesized from the given starting material. (Hint: Start with an acetoacetic ester.)

A β-ɣ-unsaturated carbonyl compound rearranges to a more stable conjugated ⍺,β-unsaturated compound in the presence of either acid or base. b. Propose a mechanism for the acid-catalyzed rearrangement.

There are other condensation reactions similar to the aldol and Claisen condensations:

a. The Perkin condensation is the condensation of an aromatic aldehyde and acetic anhydride. Draw the product obtained from the following Perkin condensation:

There are other condensation reactions similar to the aldol and Claisen condensations:

b. What compound is formed if water is added to the product of a Perkin condensation?

There are other condensation reactions similar to the aldol and Claisen condensations:

c. The Knoevenagel condensation is the condensation of an aldehyde or a ketone that has no a-hydrogens and a compound such as diethyl malonate that has an a-carbon flanked by two electron-withdrawing groups. Draw the product obtained from the following Knoevenagel condensation:

What product is obtained when the product of a Knoevenagel condensation is heated in an aqueous acidic solution?

Indicate how each of the following compounds can be synthesized from the given starting material and any other necessary reagents:

b.

Indicate how each of the following compounds can be synthesized from the given starting material and any other necessary reagents:

c.

The Reformatsky reaction is an addition reaction in which an organozinc reagent is used instead of a Grignard reagent to add to the carbonyl group of an aldehyde or a ketone. Because the organozinc reagent is less reactive than a Grignard reagent, a nucleophilic addition to the ester group does not occur. The organozinc reagent is prepared by treating an α-bromo ester with zinc.

Describe how each of the following compounds can be prepared, using a Reformatsky reaction:

a.

The Reformatsky reaction is an addition reaction in which an organozinc reagent is used instead of a Grignard reagent to add to the carbonyl group of an aldehyde or a ketone. Because the organozinc reagent is less reactive than a Grignard reagent, a nucleophilic addition to the ester group does not occur.

The organozinc reagent is prepared by treating an α-bromo ester with zinc.

Describe how each of the following compounds can be prepared, using a Reformatsky reaction:

c.

The ketone whose ¹H NMR spectrum is shown here was obtained as the product of an acetoacetic ester synthesis. What alkyl halide was used in the synthesis?

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Indicate how the following compounds can be synthesized from cyclohexanone and any other necessary reagents:

d.

Compound A with molecular formula C₆H₁₀ has two peaks in its ¹H NMR spectrum, both of which are singlets (with ratio 9 : 1). Compound A reacts with an acidic aqueous solution containing mercuric sulfate to form compound B, which gives a positive iodoform test (Problem 58) and has an 1H NMR spectrum that shows two singlets (with ratio 3 : 1). Identify A and B.

b. What carboxylic acid is formed when the malonic ester synthesis is carried out with two equivalents of malonic ester, one equivalent of 1,5-dibromopentane, and two equivalents of base?

Draw the products of the following reactions:

a.

Draw the products of the following reactions:

b.

Draw the products of the following reactions:

c.

Draw the products of the following reactions:

d.

Show how the following compound can be prepared from starting materials that have no more than five carbons: