Dehydration of Cyclohexanol

What are you looking for in the IR?

-disappearance of the OH peak- it is no longer an alcohol

-also looking to see the C-C double bond of the alkene

What does the bromine test identify?

double and triple bonds, testing for unsaturation. red color will disappear. if you add too much bromine color might not disappear

Potential issues with the experiment?

1. H+ source, has to be specific, no HCl bc substitution product will be produced

2. Reversibility

3. Possibility of Multiple Products

How do we prevent reversibility of the reaction?

Setting up as a distillation, cyclohexene has lower bp than cyclohexanol. continuously removes the product as it forms which shifts reaction equilibrium towards the product side.

How do we prevent multiple products forming?

We are not, avoiding this by performing a reaction where one product is possible

How does fractional distillation differ from simple?

There is the addition of distillation column between distillation flask and head

Why do we need an ice bath for the product flask?

To maximize product yield bc cyclohexene can evaporate

What is the orginal leaving group? What does it transform to?

Hydroxide ion, sulfuric acid protonates it to become water

Dangers of sulfuric acid?

How many possible products? What are they?

3,

Write general reaction

Write mechanism

What are we converting? Define reaction

Cycohexanol to cyclohexene, alcohol to alkene, through elimination reaction, E1 mechanism

What occurs in elimination reaction?

Nucleophile acts as a base rather than a nucleophile

Why do we use sulfuric acid?

Original leaving group is hydroxide ion which is bad leaving group.

Sulfuric acid protonates alcohol to turn into water. Conjugate base is a bad nucleophile, so substitution won’t occur

Reverse Reaction?

alkene in presence of acid and water and produce addition product. hydration

Product Analysis?

percent yield, good yield about 70%, most ppl at 40-50%. keep good yield by handling carefully after collection

what are three things we need to deal w/ to prevent product loss? how?