Diels-Alder Adduct

Offer an explanation of why anthracene preferentially forms a Diels-Alder adduct at 9,10 positions.

Resonance Structures for Anthracene

There are four reasonable resonance structures for anthracene. Draw them.

Benz/a/pyrene

A large number of polycyclic benzenoid aromatic hydrogens are known. One of these, benz/a/pyrene, is a powerful carcinogen found in tobacco smoke. Locate and then draw the structure of this hydrocarbon. Can you suggest other sources where this material might be expected to be present?

Synthetic Reaction Scheme

Outline a synthetic reaction scheme for the preparation of triphenylmethanol from: (a) Methyl benzoate (b) Diethyl carbonate

Ligroin

In the experiment, ligroin may be used as a solvent for the separation of the product from biphenyl. (a) What is ligroin? (b) Can you suggest an alternative solvent that might be used in this step?

Explanation of Behavior

Compounds such as naphthalene and 1,4-dichlorobenzene find use as mothballs since they sublime at a slow rate at atmospheric pressure. Explain this behavior in terms of the structure of the molecules.

Caffeine

(A) How many peaks would you expect to find in the NMR spectrum of caffeine? (B) What characteristic absorption bands would you expect to find in the infrared spectrum of caffeine?

Solid-Vapor Equilibrium

To color spots on TLC plates for easier visualization after elution with solvent, the plates can be "developed" in a sealed chamber containing solid iodine. Explain how the solid-vapor equilibrium operates in this instance.

Ethyl Acetate as an Elution Solvent

Caffeine is soluble in ethyl acetate. Do you think that the purity of your product could be checked by TLC using ethyl acetate as an elution solvent? Explain.

Preparation of Esters in an Experiment

Consider the following reaction: Lauric acid + Ethanol yields Ethyl laurate + Acetic acid In the preparation of the esters given in this reaction, the reaction product is extracted with 5% sodium bicarbonate solution (NaHCO3)in the isolation step. Why? What gas is evolved during this washing step? Write a balanced equation ...continues