From Wikibooks, the open-content textbooks collection

Organic chemistry is the study of compounds which contain carbon. The name 'organic' refers to the historical link between these compounds and living organisms. 'Inorganic' compounds were those which could be derived from non-living sources. Confusingly, some inorganic compounds contain carbon.

This material in this chapter is restricted to that needed by SL Chemistry students

For further material see Organic Chemistry

[edit] HL Material

Topic 20 is the additional HL material for Topic 11.

Determination of structure

This HL Sub-topic is required for Sub-topic 1 of SL Option A

Hydrocarbons

The material on benzene in this HL Sub-topic is required for Sub-topic 1 of SL Option A

Nucleophilic substitution reactions

This HL Sub-topic is Sub-topic 4 of SL Option A

Alcohols

[edit] Option G Syllabus

G.1.1: Describe and explain the electrophilic addition Mechanisms of the reactions of alkenes with halogens and hydrogen halides.

G.1.2: Predict and explain the formation of the major products in terms of the relative stabilities of carbocations.

Markovnikov’s Rule(See Mechanism above as example):

In the addition of HX to an unsymmetrical alkene, the H attaches to the C with fewer alkyl substituents, producing the more stable carbocation (Tertiary carbocations are more stable than secondary which are more stable than primary). The X then attaches to the C with more alkyl groups.

G.2.1: Describe, using equations, the addition of hydrogen cyanide to aldehydes and ketones.

G.2.2: Describe and explain the mechanism for the addition of hydrogen cyanide to aldehydes and ketones.

G.2.3: Describe, using equations, the hydrolysis of cyanohydrins to form carboxylic acids.

G.3.1: Describe, using equations, the dehydration reactions of alcohols with phosphoric acid to form alkenes.

G.3.2: Describe and explain the mechanism for the elimination of water from alcohols.

G.4.1: Describe, using equations the reactions of 2,4-dinitrophenylhydrazine with aldehydes and ketones.

G.5.1: Describe and explain the structure of benzene using physical and chemical evidence.

Physical Evidence:

All bonds of benzene are of equal length—shorter than single bonds, but longer than double.

Chemical Evidence:

Benzene does not undergo addition reactions

Heat of hydrogenation of benzene is endothermic whereas the heat of hydrogenation of a triene would be extremely exothermic

G.5.2: Describe and explain the relative rates of hydrolysis of benzene compounds halogenated in the ring and in the side chain.

The rate of hydrolysis in the side chain is much faster than benzene compounds halogenated in the ring because benzene does not undergo addition reactions. Chlorobenzene is much slower than alkanes in hydrolysis and does not undergo nucleophilic substitution for two main reasons:

1. The nonbonding pair of election of the chlorine may react with the pi bond, and become delocalized, thus strengthening (and possibly depolarizing) the C-Cl bond.

2. The high electron density of the delocalized pi bond repels the nucleophile and blocks it from the slight positive carbon atom attached to the chlorine.

G.6.1: Outline the formation of Grignard Reagents.

G.6.2: Describe, using equations, the reactions of Grignard reagents with water, carbon dioxide, aldehydes, and ketones

G.7.1: Deduce the reaction pathways given the starting materials and the product.

G.8.1: Describe and explain the acidic properties of phenol and substituted phenols in terms of bonding.

Alcohols are not very acidic because they produce an anion which contains only one resonance structure, and localized electrons.

Phenol is acidic due to its electron-withdrawing groups. As an anion, it becomes more stable due to the delocalized electrons which produce various resonance structures.

2,4,6-trinitrophenol contains many electron-withdrawing groups which cause it to be very acidic due to further delocalization of the electrons.

G.8.2: Describe and explain the acidic properties of substituted carboxylic acid in terms of bonding.

The adjacent C=O bond weakens the normally strong O-H bond.

The ion formed by the removal of the H from a carboxylic acid is more stable because of the delocalized electrons forming several resonance structures.

G.8.3: Compare and explain the relative basicities of ammonia and amines.

Ammonia is a weak base

Amines are more basic than ammonia because the inductive effect of the alkyl group pushes the electrons towards the nitrogen atom, increasing the electron density of the nonbonding electron pairs of the nitrogen.

G.9.1: Describe, using equations, the reactions of acid anhydrides with nucleophiles to form carboxylic acids, esters, amides, and substituted amides.

G.9.2: Describe, using equations, the reactions of acyl chlorides with nucleophiles to form carboxylic acids, esters, amides, and substitutes amides.

G.9.3: Explain the reactions of acyl chlorides with nucleophiles in terms of an addition-elimination mechanism.

G.10.1: Describe, using equations, the nitration, chlorination, alkylation, and acylation of benzene.

G.10.2: Describe and explain the mechanism for the nitration, chlorination, alkylation, and acylation of benzene.

G.10.3: Describe, using equations, the nitration, chlorination, alkylation, and acylation of methylbenzene.

The methyl group is an electron supplier and an activator, so it is an ortho/para-director.

G.10.4: Describe and explain the directing effects and relative rates of reaction of different substituents on a benzene ring.

G.11.1: Deduce reaction pathways given the starting materials and the product.