In this experiment, the unknown alcohol (5) was reacted with
trifluoroacetic anhydride for form a trifluoroacetate ester and trifluoroacetic
acid. Alcohol 5 was 2-pentanol, which underwent a nucleophilic substitution
reaction of exothermic esterification to form 2-pentyl trifluoroacetate and
trifluoroacetic acid, which has a pKa of -0.25. The alcohol was determined to
be 2-pentanol because the trifluoroacetate ester product had a boiling point of
112 deg.C and a refractive index value of 1.3453. The literature provided had a
boiling point of 120 deg.c and a refractive index value of 1.3456. Because the
boiling point can vary more due to ranging and contamination, the determination
was based more upon the refractive index value with coordination to the boiling
point. The actual product mass was 0.713 g, and the theoretical yield was
1.0075 g (3.88 x 10 -3 mol). This resulted in a percent yield of 70.8%. The
deduction of percent yield accumulated through the steps of the reaction.
Product could have been lost in the 2 extractions of aqueous layers, the
transfer of the organic layer to the test tube for drying, and the transfer of
the organic layer to a 3.0 mL vial for weighing.
Conclusion:
In this lab, an esterification reaction of unknown alcohol
#5 and trifluoroacetic anhydride was successfully run in order to form 2-pentyl
trifluoroacetate and trifluoroacetic acid. The unknown alcohol was determined
by the refractive index value of the ester—1.3453—and the boiling point—112
deg.c. The 2-pentyl trifluoroacetate had a percent yield of 70.8% due to
multiple extractions and transferring the product.
Corticotropin-releasing factor (CRF) is a 41-amino acid peptide derived from a 196-amino acid preprohormone. CRH belongs to corticotropin-releasing factor family and is secreted by the paraventricular nucleus (PVN) of the hypothalamus in response to stress. Ovine CRF produces a longer lasting ACTH response in humans than human CRF, CRF Trifluoroacetate
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