1. Introduction
Organic chemists synthesize new
chemical compounds in order to gain a
better understanding of the structures
of different molecules. This
understanding can help chemists
develop new molecules with qualities
that are structure-specific.
Synthesizing new organic
compounds using boronic acids
Analyzing and determining
structures of new synthetic
organic compounds to determine
if they have any unique properties
using melting point, 1
H NMR
spectra, 13
C NMR spectra , TLC,
FT-IR spectra, and UV-VIS spectra
Characterizing the new
compounds based on the
structure and the unique qualities
of the compound
Objectives
Calculate and measure out 2 mmol
of each of the reactants based on
the molecular weight from the
bottle or from the chemical catalog
Collect 2 clean 50-ml beakers and
add each of the reactants to its own
respective beaker under the flow
hood
Dissolve each reactant in 10 mL
50% aqueous ethanol, using heat if
necessary to drive all of the solvent
into solution.
Simultaneously, Pasteur pipet equal
amounts of both solutions into a
third beaker, ensuring that equal
amounts of reactant are delivered
to the solution at relatively the
same time
Let solution sit in the flow hood
overnight until almost completely
evaporated and the product has
completely fallen out of solution
The next day, vacuum filter out
precipitate from solution using ice-
cold deionized water to suspend
the product
Measure product in order to
calculate a percent yield of product
based on the predicted molecular
weight
Prepare NMR tubes with samples of
the product and analyze under
proton and carbon NMR to help
predict the structure of the product
obtained.
Take TLC to test whether the
substance is fluorescent under UV
light
General Procedures
Projects
M.P. (O
C) Yield 1
H NMR 13
C NMR Appearnce
50 195-196 80% 9/9 H peaks 13/14 C peaks White, fluffy, crystals
51 >260 84% 10/10 H
peaks
Not soluble
enough
Fine, yellow powder
54 >260 88% 11/11 H
peaks
16/18 C peaks Fine, light yellow
powder
Methods of Characterization and Lab Techniques
Thin Layer Chromatography (TLC) A plate coated with silica gel separates out molecules
in a sample. TLC served as an early indicator of purity in a compound. It also provides an
instrument through which fluorescence can be demonstrated by placing the plate under
long-wave UV light.
1
H Nuclear Magnetic Resonance (NMR) Spectra A spectrum used to measure the amount
of hydrogen atoms present in a molecule. The NMR machine records in parts per million
the locations of each of the different hydrogen atoms in the molecules using magnetic
fields aimed in different directions.
13
C NMR Spectra A spectrum used to measure and locate the different carbon atoms
within the molecule. The NMR instrument can be used to confirm possible molecular
structures of new compounds.
Melting Point Apparatus The machine that measures melting points helps characterize
compounds and can be an indication of purity in a compound. A smaller melting point
range supports a more pure compound compared to a larger melting point range which
leads to a less pure compound. The highest temperature that can be measured was 260O
C.
Rotary Evaporator The rotary evaporator uses heat, rotation, and a vacuum to quickly dry
out and isolate a sample from a solution.
Fourier Transfer Infrared Spectroscopy (FT-IR) This machine measures infrared
absorbencies within the bonds of the molecules in the compound. This method can help
researchers identify certain specific chemical bonds in a compound.
UV-VIS The UV-VIS machine measures absorbencies of the compound in the UV and visual
wavelength range. The lambda max of the spectrum helps to characterize a new
compound.
Column Chromatography One of the methods of purifying a mixture of compounds is
column chromatography. In this filtration system, the mixture travels through silica gel,
separating out larger molecules from faster-travelling smaller molecules.
Recrystallization Another method of purification of a compound, recrystallization is a
process where a mixture of compounds is driven into a solution with heat until completely
dissolved and then allowed to cool until the desired product falls out of solution and
recrystallizes.
Special Thanks to:
Dr. Groziak
Aurora, Brian, Dung, Elena, Eric, Tesfay
Dr. Michele Parker, Dr. Katy Korsmeyer, and Mary Lou Stuart
SV-STEM program
California State University East Bay
Highlights
Learning how to use the NMR
machine for carbon and proton
spectra and being able to analyze
the data
Working in a real-world lab setting