Properties of HydrocarbonsProperties of Hydrocarbons

Hydrocarbons

The three key categories of hydrocarbons are saturated, unsaturated, and

aromatic.

These categories have a large influence on both the reactivity and physical

properties of organic compounds.

Saturated hydrocarbons are relatively chemically inert.

Unsaturated hydrocarbons are subject to addition and oxidation reactions.

Aromatic hydrocarbons are more likely to undergo substitution reactions instead of

addition reactions.

Saturated Unsaturated Aromatic

The three known compounds for the experiement are cyclohexane, cyclohexene,

and toluene.

Each student will receive one unknown prepared by the TA. Note your unknown’s identifying code in your lab notebook.

For each procedure involving a solvent, a blank will be included that is just the

solvent for the test.

All test tubes should be clean and DRY. Residual water or acetone can interfere

with your tests.

For each test, your results must include both observations and interpretation for each known and your unknown.

Cyclohexane

CH3

Cyclohexene Toluene

Experimental Procedure

Unknown Blank

? Solvent

Put 2 mL of water in five (5) test tubes. Clearly mark your test tubes to identify which

type of hydrocarbon was added.

PART A: Add 2 to 3 drops of each liquid to it’s test tube and shake.

Record your observations of water solubility (don’t forget interpretation).

PART B: Reexamine your test tubes to determine if the non-soluble compounds

are more dense or less dense than water.

PART C: Skip this part. No open flames in Organic Chemistry Lab.

Cyclohexane

CH3

Cyclohexene Toluene Unknown Blank

? water

Solubility and Density

Starting with freshly cleaned test tubes, add 1 mL of methylene chloride to five (5)

test tubes. Clearly mark your test tubes to identify which type of hydrocarbon was

added.

PART D: Add 3 to 4 drops of each liquid to it’s test tube.

Add several drops of bromine solution to each test tube and watch for a loss of color.

What does this color loss indicate?

Record your observations (don’t forget interpretation).

Cyclohexane

CH3

Cyclohexene Toluene Unknown Blank

? Methylenechloride

Reaction with Bromine (Bromination)

Starting with freshly cleaned test tubes, add 1 mL of acetone to five (5) test

tubes. Clearly mark your test tubes to identify which type of hydrocarbon was

added.

PART E: Add 3 to 4 drops of each liquid to it’s test tube.

Add several drops of potassium permanganate solution to each test tube and

watch for a loss of color. What does this color loss indicate?

Record your observations (don’t forget interpretation).

Cyclohexane

CH3

Cyclohexene Toluene Unknown Blank

? Acetone

Reaction with KMnO4 (Oxidation)

Starting with freshly cleaned test tubes, add 1 mL of concentrated sulfuric acid to

four (4) test tubes. Clearly mark your test tubes to identify which type of

hydrocarbon was added.

PART F: Add 3 to 4 drops of each liquid to it’s test tube, one drop at a time.

Carefully watch for signs of a reaction (sample dissolves, changes color,

becomes warm, or forms a precipitate). If no reaction occurs at room

temperature, warm the sample in a warm water bath.

Record your observations (don’t forget interpretation).

Cyclohexane

CH3

Cyclohexene Toluene Unknown Blank

? None

Reaction with H2SO4

There are three types of liquid waste bottles in the hood:

Aqueous (Parts A, B and D)

Organic (Part E)

Acid (Part F)

Both sulfuric acid and the bromine solution can cause burns.

Please handle carefully. (When shaking your test tubes, do you use

your thumb to cover the opening?)

Are you prepared for your MIDTERM?Are you prepared for your MIDTERM?

Final NotesFinal Notes