acs 2012 flashtalk

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