Thursday, June 22, 2006

Exp 015

Objective:To convert adrenaline to a catechol aldehyde using acid catalysis. How this fits into the synthesis of anti-malarials is described here.

Procedure:Taken from Preparation and Properties of p-Hydroxyphenylacetaldehyde and 3-Methoxy-4-Hydroxyphenylacetaldehyde by Jay H. Robbins Archives of Biochemistry and Biophysics.A solution of adrenaline (217 mg, 1.18 mmol) in 85% phosphoric acid (6 mL) was heated in a 12mL vial to 120C in a glycerol bath then removed from heat and allowed to cool for 30 secondsthen added to water (36 mL) and then saturated with NaCl, followed by extraction with ether (17mL, 10mL, 10mL).

Video of set upTwo stains were done without a TLC run Ninhydrin stain Ansaldehyde stainRun in pure methanol visible with iodine.HNMR was obtained of the product after it was re-dissolved with ether, dried with MgSO4, and vacuumed again to have a net weight of 15mg. There is no carbonyl peak that I can see and the NMR seems scewed. There is an expanded version as well.

Based on the published H-NMR of DOPAL alone there does not seem to be any aldehyde formed. However HMR spectra of 4-alkylcatechols, such as 4-methylcatechol, with the three aromatic hydrogens genrally appearing in the 6.5-6.9 ppm range gives reason to believe that the published spectra is incorrect.

The aldehyde was not produced however the reaction will be attempted once more.


16:55] turn on hot plate to heat glycerol
17:10] put phosphoric solution in 10mL vial and then in heated glycerol bath
17:23] solution heated to 120C, taken off of heat and cooled for 30seconds. added to 36mL distilled water.
19:00] Saturated with NaCl(didn't filter)
19:13] Poured solution without excess NaCl into a separatory funnel. Extracted with 17mL anhydrous ether
19:20] Extracted with 10mL anhydrous ether
19:24] Extracted with 10mL ether
19:30] Performed TLC 1:1 methylene chloride hexanes (no movement), pure methylenechloride (no movement), pure methanol (some movement)**Ninhydrin and Ansaldehyde stains give little information.
rotovaped ether extracts
vacuumed off remains from rotovap. wt=15mg dry product
would not disolve in methylene chloride but did disolve in methanol
TLC of 1:1 methylene chloride in hexanes showed nothing. Methanol had same movement


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