Properties ofProperties ofHydrocarbonsHydrocarbons

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. Your results must include both observations and interpretation.

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 (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

? Solvent

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

? Solvent

Reaction with Bromine

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

? Solvent

Reaction with KMnO4

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, including the generation of heat. If no reaction occurs, 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?)

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Final NotesFinal Notes