The number of half lives that have passed when radioactivity of a sample has dropped to 1 / 4 of its original intensity is to be stated. Concept introduction: The elements whose nucleus decays spontaneously are known as radioactive elements. The decay is accompanied by the emission of alpha particles, beta particles, and gamma rays. All the elements which have an atomic number greater than 83 are radioactive. Half-life of a radioactive substance is defined as the time taken by half of its atoms to decay.

Question

Kumada Coupling: 1. m-Diisobutylbenzene below could hypothetically be synthesized by Friedel-Crafts reaction. Write out the reaction with a mechanism and give two reasons why you would NOT get the desired product. Draw the reaction (NOT a mechanism) for a Kumada coupling to produce the molecule above from m-dichlorobenzene. Calculate the theoretical yield for the reaction in question 2 using 1.5 g of p-dichlorobenzene and 3.0 mL isobutyl bromide. What signals appeared/disappeared/shifted that indicate that you have your intended product and not starting material? What other impurities are present in your product and how do you know?

Answer 1

Question

Chapter 20, Problem 17E

Interpretation Introduction

Interpretation:

The number of half lives that have passed when radioactivity of a sample has dropped to 1/4 of its original intensity is to be stated.

Concept introduction:

The elements whose nucleus decays spontaneously are known as radioactive elements. The decay is accompanied by the emission of alpha particles, beta particles, and gamma rays. All the elements which have an atomic number greater than 83 are radioactive. Half-life of a radioactive substance is defined as the time taken by half of its atoms to decay.

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