Experiment 2: Catalytic Alkene Hydrogenation

hydrogenation

addition of a molecule of H2 across a unit of unsaturation

Is this molecule Saturated or unsaturated

unsaturated

Is this molecule saturated or unsaturated

Saturated

How many units of unsaturation does this have?

• 0

• 1

• 2

• 3

• 4

• 5

4

Which of the following statements about unsaturated fats is incorrect?

• Unsaturated fats are believed to be healthy

• Unsaturated fats can contain trans alkenes

• Unsaturated fats are made up of a molecule of glycerol and 3 fatty acids

• Unsaturated fats can react with oxygen at the allylic positions and become rancid

unsaturated fats are stable

What exactly is studied in this experiment?

• selective hydrogenation of ethyl cinnamate through palladium catalysis

What is a reduction reaction? What is being reduced in this case?

1. carbons form new bonds to hydrogens

2. the alkene of ethyl cinnamate

what is the role of Pd/C ( palladium on carbon) the experiment?

it is a hydrogenation catalyst

What is a reflux condenser?

• The key component to a reflux apparatus

• it has a hollow inner layer where cold water passes through to cool the inner surface

• acts to cool and condense liquid so solvent doesn’t boil away

When should experimentalists consider using a reflux apparatus?

• any time a heating plate is used

• when the reaction mixture is heated near or over the boiling point of at least one component

• it is always optional because it does not affect the outcome of the experiment

• only when ethanol is used as the solvent

• when the lab temperature is hot

• when the reaction mixture is heated near or over the boiling point of at least one component

what is a chromophore?

the part of a molecule that is responsible for absorbing light

when would you use a TLC stain?

When a molecule that does not have a chromophore is being analyzed

How does a potassium permanganate ( KMnO₄ ) stain work?

• it is an oxidant

• oxidizes molecules with oxidizable functional groups

  • alkenes, alcohols, amines, aldehydes, alkynes