Esterification

Why do Nacl plates used for IR need to be handled with care?

Easily breakable and attached by moisture

neat liquid

a liquid that has not been mixed with anything else.

What are the problems using a low viscosity liquid when taking an IR spectrum

When squeezed between salt plates may be so thing that the short path length gives peaks that are too weak and hard to interpret

Very viscosity liquid

peaks become too intense

Why are glass, quartz, and plastics not used as IT sample holders?

These are bad IR sample holders because they are opaque to IR radaition and they obsrob radiation. Sample holders must be made of other transparent materials

Why is Carbon Carbon triple bond streching band for a symmetrical acetlyene almost nonexistent on an IR spectra?

No dipole movement when it streches

Le Chatelier

States that if a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress.

How can Le Chatelier principle be used for this esterifiction

Use an excess of either alcohol or ester to drive the reaction to completion
Remove water through drying agents
Preferentially remove water as azetrope

Which Le Chatelier principle was used

Azeotropic preferred over excess ether alcohol or ester since (COOC, OH, COOH) have BP with 10 degrees of each other.
Preferred over olecular sieves because of higher yields.

Why are simple and fractional distillation not suitable for seperating products from reactants if excess reactant used in syntheis of n-butlyacetate

The BP is too small and you have a very pure compound

How can ater be removed

Molecular sieves (drying agent)
Azeotropic distillation

Why can you only use molecular sieves instead of other drying agents?

Other drying agent would not remove water at the high tempertures to make esters

Why was apparatus set up the way it was?

10-15 degree angle so that enough condensate can collect in the corked sidearm and the water/organic levels can separate.
Wrapping the condenser with paper towel so that vapor can condense and flow back into the sidearm

Azeotropic distillation

water is removed from the reaction mixture to shift the equilibrium and drive reaction to completion

TLC

Anaylze purity of the product. If during the reaction to analyze if the reaction is complete

IR

To analyze purity of product

Simple Distillation

To seperate ester from the 1-butanol (even though b.p. is similar, this is okay because only a small portion of starting material is present.

Acid OH (IR)

2500-3200cm

Alcohol OH (IR)

3200-3600

C double bond O

1650-1815

CO

1050-1200

Role of Resin

Acts as an acid catalyst
Easily filtered

Disadvatages of using traditional acid catalyst

Not easily seperated from the ester.

Catalytic cid effect on intermediates

All intermediates are neutral or positive

Reflux

Heating of a reaction mixture to a solvent's boiling point for an extended period of time withoutexaporation

Why would there might be an OH peak in the IR

The reaction is in equilibrium and some starting material might be presented.
Not due to water since we dried ether with CaCl2 pellets

How would you further purify the solution?

Simple distillation

Lactones

Cyclic esters
Form from intermolecular esterification
Strating material: Hydroxyl carboxylic acid (56 member ring)

Why base catalyzed esterification using carboxylic acid and alcohol not possible?

The acididc hydrogens of the carboxylic acid would protonate the base, yielding the conjugate base. Hydroxide (OH) cannot acctack the carbonly carbon because of repulsion of negative charges