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Examining the Literature to
Demonstrate the Need for the
Careful Checking of
Reported Measurements
Matthew McBride
Undergraduate Chemistry Major
Drexel University
Bradley Research Group
CINF Flash
ACS Symposia #244
Philadelphia, PA
August 19, 2012
Main Points
1. Published results need to be compared
for consistency with the rest of
literature
2. Missing information in a published
article decreases the reliability of the
reported results
Preparing a Synthesis
Desire to synthesize:
(1E,4E)-1,5-Di(2-naphthyl)-1,4-pentadien-3-
one
Aldol condensation between two molecules of
2-naphthaldehyde and one molecule of
acetone
(http://www.chemspider.com/4523376)
Search the LiteratureUsing a database such as Reaxys©
Inconsistency
Conflicting reported melting points
Identify Compound
Always need to confirm that the listed melting
point corresponds to the desired compound
Always need to confirm that Reaxys© has
correctly listed the melting point
(doi: 10.1139/v90-351)
ONS Webservices
Conclusion: The melting point value of
114°C is an outlier
(http://onswebservices.wikispaces.com/meltingpoint)
[Andrew Lang]
Synthesis Procedure
How to make the compound
Reference to Organic Syntheses procedure(doi: 10.1016/0040-4020(96)00788-0)
(http://www.orgsyn.org/orgsyn/orgsyn/prepcontent.asp?prep=cv2p0167)
ConcentrationClaim that 1 mole of aldehyde can be
dissolved to make an approximately 0.5M
solution in 1:1 ethanol/water mixture
Picture: 0.16M solution
2-naphthaldehyde visible
Paper lacking details
(http://onschallenge.wikispaces.com/EXP337)
Drug Discovery If interested in the compound as a potential
drug, check the bioactivity results
Cytotoxicity
Compound identified
Toxicity results listed against tumor cell lines
(doi:10.1016/j.bmc.2008.10.044)
Problem?Check the characterization of the compound
(B46)
There is none! No melting point, percent
yield, NMR..etc.
No scientific evidence to support the claim
that the listed compound was tested.
Reduces the reliability of the reported results
(doi:10.1016/j.bmc.2008.10.044)
CharacterizationHNMR spectrum should have a singlet (2H)
All peaks represent an even number of
hydrogen atoms
CharacterizationCompare HNMR spectral data from literature
Need to check spectral data for consistency
(US Patent 20100152493)
(doi: 10.1016/0040-4020(96)00788-0)
(doi: 10.1139/v90-351)
Summary
Reported measurements, such as
melting points, listed in databases must
be considered in context with all
published values to identify outliers
Missing data and characterization
information reduces the impact and
reliability of published work