Ibuprofen Resolution

Purpose:

In this experiment a process for obtaining a substantially pure enantiomer of ibuprofen is described by the process that utilizes first an enantiomerically enriched mixture of ibuprofen. This enriched mixture dissolves in a solvent and solid racemic ibuprofen is separated, leaving a mother liquor comprising, the solvent and the enriched enantiomer substantially free of the other enantiomer. Racemic is an optically inactive because the two isomers rotate plane polarized light in opposite directions. In contrast to the two separate enantiomers, which generally have identical physical properties, a racemate often has different properties compared to either one of the pure enantiomers. Different melting points and solubility's are very common.

Reagent Table:

M.WM.PB.P DensitySolubility

Ibuprofen206.376immiscible

2-Propanol60.10-8682.3.785miscible

MTBE88.15-10955.2.74044.8

H2SO498.08103371.84miscible

Methyl benzyl Amine121.181185.939immiscible

Structures:

Ibuprofen

2-Propanol

MTBE

H2SO4

Methylbenzyl Amine

Observations and Data:

Part B

Weight of watch glass--- 28.563 grams

Weight of crystals and watch glass--- 31.047 grams

Weight of crystals--- 2.484

Skeletal formula of the (R)-ibuprofen molecule.

Enantiomers of 2-Butanol by + and - labels

Ibuprofen

grams

Part C

Weight of (+)-Ibuprofen---54.226 grams

Weight of (+)-Ibuprofen Dry --- 54.545 grams

Weight of (+)-Ibuprofen---.319 grams

Class average ---1.992 grams

Angle of rotation --- 2.8 degrees

Part D

Weight of pre-weighted beaker with boiling chip--54.090 grams

Weight of product and beaker--54.744 grams

Weight of product--- .654 grams

Class average - 3.068 grams

Melting point of purity---162 degrees

Melting of impurity ---- 56 degrees

Discussion:

In this experiment a process for obtaining a substantially pure enantiomer of ibuprofen is described by the process that utilizes first an enantiomerically enriched mixture of ibuprofen. In chemistry racemization refers to partial conversion of one enantiomer into another. Chiral molecules have two forms which differ in their optical characteristics: The levorotatory form (−) will rotate the plane of polarization of a beam of light to the left, while the dextrorotatory form (+) will rotate the plane of polarization of a beam of light...