17.6: Reaction Examples

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SOLVED PROBLEM 8-1, p. 329

Analysis: Markovnikov addition of HBr to the C=C bond. Use HBr:

Complement:

Analysis: Anti-Markovnikov addition of HBr to the C=C bond. Use HBr in the presence of peroxides

Retrosynthetic analysis, or retrosynthesis:

Recommended problem: 8-4, p. 330

OXYMERCURATION - DEMERCURATION, ALSO CALLED OXYMERCURATION - REDUCTION

Markovnikov alcohol

Markovnikov alcohol without rearrangement

Contrast with addition of water in the presence of strong acid:

HYDROBORATION - OXIDATION SEQUENCE.

An effective way to make Anti-Markovnikov alcohols. Water adds to the double bond with syn-stereochemistry.

Anti-Markovnikov alcohol

SOLVED PROBLEM 8-3, p. 339

Problem 8-15 (b)

Can I make B from A by hydroboration - oxidation?

Notice that the methyl and the alcohol group are cis to each other.

Analysis:

Answer: NO

Recommended: 8-15 (c), p. 342

ADDITION OF CHLORINE OR BROMINE TO THE C=C BOND

Anti addition yields the trans product, which is chiral. Therefore the enantiomer also forms.

Recommended: 8-17, p. 345

Variation with water:

Recommended: 8-5 and 8-6, p. 347

CATALYTIC HYDROGENATION - Transformation of alkenes into alkanes (syn addition of hydrogen).

Recommended: 8-23, p. 350

SYN HYDROXYLATION - Syn addition of OH / OH to the C=C bond.

ANTI HYDROXYLATION SEQUENCE- Anti addition of OH / OH to the C=C bond.

Recommended for syn and anti hydroxilation: 8-34 (all), p. 359

OXIDATIVE CLEAVAGE: Strong oxidation with potassium permanganate.

In this reaction each of the sp² carbons involved in the pi bond gets oxidized to its maximum possible oxidation state. Refer to notes set # 20 (Oxidation and Reduction in Organic Chemistry) to find out what these states are.

OXIDATIVE CLEAVAGE: Ozonolysis

In this reaction each of the sp² carbons involved in the pi bond gets oxidized either to aldehyde or ketone, depending on whether it ends up at the end of a carbon chain or in the middle after the pi bond cleaves. If the oxidized carbon ends up at the end of a carbon chain it becomes an aldehyde, otherwise it becomes a ketone.

Recommended strong oxidation (oxidative cleavage) with KMnO₄ and with ozone: 8-7, 8-36, and 8-37, p. 362-363.

Recommended problems from the end of the chapter: 47 (all), 49 ( a-f ), 58 (all), 63