Hydrocarbons: Overview

Organic compounds made up of only carbon (C) and hydrogen (H).

What are hydrocarbons?

Hydrocarbons that contain one or more benzene rings with delocalized π-electrons.

Define Aromatic Hydrocarbons.

A rule that states a compound must be cyclic, planar, fully conjugated, and contain (4n + 2) π-electrons to be aromatic.

What is Huckel’s Rule?

Benzene (C₆H₆).

Give an example of a simple aromatic compound.

They undergo electrophilic substitution reactions.

How do aromatic hydrocarbons generally react?

A sooty flame due to higher carbon content.

What is produced during the combustion of aromatic hydrocarbons?

Hydrocarbons that consist of straight or branched chains or cyclic (but non-aromatic) structures.

Define Aliphatic Hydrocarbons.

Hydrocarbons that contain only single bonds between carbon atoms.

What are saturated hydrocarbons?

CnH₂n+₂.

What is the general formula for alkanes?

Methane (CH₄).

Name a simple alkane.

They are less reactive and mainly undergo combustion and substitution reactions.

Describe the reactivity of saturated hydrocarbons.

With a clean, blue flame.

How do saturated hydrocarbons burn?

Hydrocarbons that contain double or triple bonds between carbon atoms.

What are unsaturated hydrocarbons?

CnH₂n.

What is the general formula for alkenes?

Ethene (C₂H₄).

Give an example of an alkene.

CnH₂n−₂.

What is the general formula for alkynes?

Ethyne (C₂H₂).

Provide an example of an alkyne.

They undergo addition reactions.

How do unsaturated hydrocarbons generally react?

It may produce a sooty flame due to higher carbon content.

What is the result of the combustion of unsaturated hydrocarbons?

To test for unsaturation (double/triple bonds).

What is the purpose of the Bromine Water Test?

Decolorization of the reddish-brown bromine water.

What indicates unsaturation in the Bromine Water Test?

The presence of alkenes or alkynes.

What does a color change to brown in Baeyer’s Test indicate?

A clean, non-sooty flame.

What flame characteristic indicates saturated hydrocarbons?

Ignition Test.

What test determines the type of hydrocarbon based on flame characteristics?

All hydrocarbons are insoluble in water.

How do hydrocarbons behave in water?

Organic compounds containing carbon and a halogen atom (F, Cl, Br, or I).

What are organic halides?

The halogen is attached to a carbon atom connected to only one other carbon.

Describe a primary organic halide.

2-Bromobutane (C₄H₉Br).

Provide an example of a secondary organic halide.

The presence of halogens.

What is indicated by a green flame in the Beilstein Test?

A substitution nucleophilic unimolecular reaction that involves the formation of a carbocation.

Define S_N1 reaction.

The formation of the carbocation.

What is the rate-determining step in S_N1 reactions?

A substitution nucleophilic bimolecular reaction that occurs in one step.

Describe the S_N2 reaction mechanism.

A strong nucleophile.

What type of nucleophile is required for S_N2 reactions?

S_N1 can lead to racemization; S_N2 results in inversion of configuration.

How does stereochemistry differ between S_N1 and S_N2 reactions?

It depends on the number of other carbons connected to the carbon holding the halogen.

What distinguishes primary, secondary, and tertiary organic halides?

S_N2 reaction.

What type of reaction mechanism is bimolecular?