Methyl Stearate from Methyl Oleate

Title: Methyl Stearate from Methyl Oleate

Objective: To convert an unsaturated fatty acid (methyl oleate) to a saturated fatty acid (methyl stearate) by process of catalytic hydrogenation.

Reference: “Introduction to Organic Laboratory Technique: A Microscale Approach;” Pavia, Lapman, Kriz, Engel; Saunders college Publishing; 3rd edition, 1999.

Reaction:

CH3(CH2)7-CH=CH-(CH2)7-C-OCH3 CH3(CH2)7-CH2-CH2-(CH2)7-C-OCH3

(methyl oleate) ∥ (methyl stearate) ∥

O O

Reagents:

Substance Source Millimoles (mmol) Mass(g)/Volume(ml)

Methyl oleate Not applicable 0.5362 0.159g/1.0ml

10% Pd/C Acros (Lot #A013537401) 0.2533 0.03g

Yield:

Methyl Oleate (0.159g/1.0ml): 0.5362mmol

Methyl stearate (0.109g): 0.3651mmol

Percent Yield: [0.3651/.05362(100)] => % yield =68.1%

Melting Point (Methyl stearate): 36-37°C (literature, 39°C)

Procedure, Observations and Data:

To round-bottom flask (10ml) added sequentially; methyl oleate (1ml, 0.159g, 05362mmol), methanol solvent (dry 6.0ml), stirring bar, 10% Pd/C (0.03g/0.2533mmol). Placed septum over flask, flushed with H2 attached balloon (9”) to luer lock needle, injected/pierced septum (see apparatus drawing below). Heated flask (sand bath) maintained at 40°C for 45-60min. Centrifuged (15min), decanted supernatant liquid (leaving black catalyst in tube), cooling induced crystals (ice bath). Collected crystals by vacuum filtration (Hirsh funnel), set to dry, weighed (0.109g/0.3651mmol), established melting point [36-37°C (literature, 39°C)].

Discussion:

After catalytic hydrogenation one molar equilvant of H2 of was consumed in the...