Lecture 29. Hand in Lecture Problem 10 Sweeteners Quiz 8 on Thursday in lecture This Week in Lab: Synthetic #2 Final Report; Lab Clean-up & Check-out! Remember to bring all graded PreLabs and Aldrich to lab. Sweeteners. Carbohydrates: Mono- and disaccharides Examples:
Mono- and disaccharides
Sugar, corn syrup, maple syrup, juice concentrates
Shape must fit into specific
receptors in taste buds.
When shape is slightly modified, it is no longer
Aspartame is metabolized in the body into:
methanol (wood alcohol), phenylalanine, and aspartic acid
Phenylalanine is an essential amino acid and is a
precursor for the synthesis of tyrosine and several
Excess phenylalanine is broken down into
fumarate and acetoacetate - normal energy metabolism.
If lacking the enzyme to convert
phenylalanine to tyrosine, have
Phenylalanine is then converted to phenylketones instead.
PKU could lead to mental retardation if not detected or treated.
Products that contain aspartame carry an information
label for phenylketonurics.
Reports of formaldehyde
Methanol quickly converts to
formaldehyde in the body.
Formaldehyde causes severe damage to the neurological system, immune system, and causes permanent genetic damage at extremely low doses.
Two main constituents:
Make the methyl
ester of phenylalanine
2. Make a peptide (amide)
bond between phenylalanine
and aspartic acid
Overall - two main steps to this synthesis
Only the S enantiomer of phenylalanine is desired for use. The R and
S enantiomers can be separated before the esterification reaction.
Design a synthesis of the following ester. You can use
either the Fisher esterification method or the
alternative esterification method. Give the overall
reaction equation with starting materials, reagents, and
main organic product.