Ethyl L-lactate can be tuned with a cosolvent to create polarity conditions ideal for synthesizing aryl aldimines that crystallize directly out of solution within minutes under ambient conditions in excellent yields and requiring no further purification.
One of the most significant difficulties encountered when directing undergraduate research and developing new laboratory experiments is how to efficiently manage the data generated by a number of students. Cloud computing, where both software and computer files reside online, offers a solution to this data-management problem and allows researchers to coordinate their efforts just as easily whether they are working in the same laboratory or laboratories halfway around the world. This article discusses the use of Google Docs, a free cloud suite of office programs, for the management of a research project and in the development of a new experiment for the undergraduate organic laboratory.
As infrared spectroscopy (IR) is frequently used in undergraduate organic chemistry courses, an inductive introduction to IR spectroscopy that uses index cards printed with spectra, structures, and chemical names is described. Groups of students are given an alphabetized deck of these “IR cards” to sort into functional groups. The students then determine each functional group’s infrared “signature” by comparing several spectra containing a specific functional group. Response to the IR cards was favorable, and students were more proficient in subsequent laboratories that used IR spectroscopy. This experiment is suitable for use in a one-semester or full-year organic course.
Primary cations of the form
XCH2CH2
+ (1) are
unstable with respect to the bridged isomer
cyclo-(CH2)2X+
(2) or the hydride-shift isomer
CH3CHX+ (3).Two independent
hydrogen isotope experiments for X = OH demonstrate
that gaseous HOCH2CH2
+
(1a) gives less of its bridged isomer, protonated oxirane
(2a), than of its hydride-shift
isomer, protonated acetaldehyde (3a).Metastable ion
decompositions of ionized HOCH2CH2OPh
show that the radical
cation decomposes via an ion−neutral complex containing 3a
and phenoxy radical. Deuterium labeling studies
exhibit no detectable interconversion of the two
sp3-carbons, implying that complexes containing
2a are not formed
to a measurable extent. An independent neutral product study looks
at the radioactive oxirane and acetaldehyde
produced when tritium on the methyl group of gaseous
CH2TCHTOH undergoes radioactive decay. Loss of a
beta-particle and a helium atom forms transient, tritiated 1a.
Ions from isomerization of this radiolabeled primary
cation
were deprotonated by Me3N and gave a >97% yield of
acetaldehyde. Quantitative assessment of possible routes
to
acetaldehyde (including rearrangement of excited 2a) implies
that 1 undergoes hydride shift at least 5 times
faster
than bridging by neighboring oxygen.
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