Your comments on bees, stereochemistry, battery safety and Christmas clean-ups
That’s stereochemistry
It is very true that today ‘visualising molecules as 3D objects (as anticipated by van’t Hoff and Lebel over one hundred years ago) is secondary school chemistry’ (Chemistry World, September 2017, p32). In particular, van’t Hoff, spoke of ‘the place atoms occupied in space’, creating the impression that the molecules formed by the corresponding atoms is a fixed structure regardless of the space it occupies. However, to what state did van’t Hoff refer? The crystalline solid, the liquid, the solution, the vapour or the gas? This has important consequences in the field of stereochemistry.
It is now evident that single, relatively small molecules, or even large biological systems such as proteins, show different structures when studied through NMR spectroscopy in solution and through X-ray crystallography.1 Changes in crystal symmetry, dipole moment determinations and IR studies make stereochemistry a very intriguing way of looking at molecules. The 2017 Nobel Prize in chemistry (Chemistry World, November 2017, p14) supports the validity of these conclusions.
Máximo Barón CChem CSci FRSC
Mississauga, Canada
Reference
M Barón, A Bain and R Conde, Can. J. Chem., 2017, 95, 736 (DOI: 10.1139/cjc-2016-0657)
That’s stereochemistry
It is very true that today ‘visualising molecules as 3D objects (as anticipated by van’t Hoff and Lebel over one hundred years ago) is secondary school chemistry’ (Chemistry World, September 2017, p32). In particular, van’t Hoff, spoke of ‘the place atoms occupied in space’, creating the impression that the molecules formed by the corresponding atoms is a fixed structure regardless of the space it occupies. However, to what state did van’t Hoff refer? The crystalline solid, the liquid, the solution, the vapour or the gas? This has important consequences in the field of stereochemistry.
It is now evident that single, relatively small molecules, or even large biological systems such as proteins, show different structures when studied through NMR spectroscopy in solution and through X-ray crystallography. Changes in crystal symmetry, dipole moment determinations and IR studies make stereochemistry a very intriguing way of looking at molecules. The 2017 Nobel Prize in chemistry (Chemistry World, November 2017, p14) supports the validity of these conclusions.
Máximo Barón CChem CSci FRSC
Mississauga, Canada
Neonicotinoids no more
I was pleased to see the UK environment secretary had decided to back the EU ban on the use of neonicotinoid pesticides (Chemistry World, December 2017, p9). In a previous letter (Chemistry World, June 2013, p45) I noted that the moratorium then proposed was an opportunity for both the agrichemical companies and researchers to intensify their studies to get more data on the effects of neonicotinoids on bees and bumblebees in particular.
Over the past four years a large number of studies have contributed overwhelming evidence that bees are ‘negatively impacted’ even by typical application levels, which had been the main criticism of the agrichemical industry. It is disappointing to hear that the companies involved continue to protest, despite evidence that would have convinced any other part of the chemical industry. Surely now enough is enough!
Mike Welch FRSC CChem
Warwick, UK
Battery safety
I am glad that Atsuo Yamada and others are researching lithium ion batteries that will be less prone to fire and explosion. However I question whether batteries using the organic electrolyte proposed, trimethyl phosphate, would be any safer than existing alternatives.
In general, substances that can alkylate oxygen and nitrogen atoms tend to be carcinogenic. Trimethyl phosphate is clearly carcinogenic in rodents. Having worked on the recycling of batteries, I know that in the recycling sector it is common to shred unwanted batteries, taking care to avoid violent events caused by stored electrical energy, to form what is known as ‘black mass’. This black mass is then processed and then used as a source of materials. The replacement of the carbonate solvents with trimethyl phosphate has potential to reduce the threat posed by fires, but would introduce a toxic threat into battery recycling sites and whenever a battery leaks.
I believe dimethyl alkylphosphonates (other than dimethyl methylphosphonate, which is a possible chemical weapon precursor) would be better as solvents for lithium battery electrolytes. The replacement of a methoxy group with an alkyl group would greatly reduce the potency of the compound as an alkylation agent. We must consider safety throughout the entire lifecycle when designing a safer battery.
Mark Foreman CChem MRSC
Göteborg, Sweden
Battery safety
I am glad that Atsuo Yamada and others are researching lithium ion batteries that will be less prone to fire and explosion.1 However I question whether batteries using the organic electrolyte proposed, trimethyl phosphate, would be any safer than existing alternatives.
In general, substances that can alkylate oxygen and nitrogen atoms tend to be carcinogenic. Trimethyl phosphate is clearly carcinogenic in rodents. Having worked on the recycling of batteries, I know that in the recycling sector it is common to shred unwanted batteries, taking care to avoid violent events caused by stored electrical energy, to form what is known as ‘black mass’. This black mass is then processed and then used as a source of materials. The replacement of the carbonate solvents with trimethyl phosphate has potential to reduce the threat posed by fires, but would introduce a toxic threat into battery recycling sites and whenever a battery leaks.
I believe dimethyl alkylphosphonates (other than dimethyl methylphosphonate, which is a possible chemical weapon precursor) would be better as solvents for lithium battery electrolytes. The replacement of a methoxy group with an alkyl group would greatly reduce the potency of the compound as an alkylation agent. We must consider safety throughout the entire lifecycle when designing a safer battery.
Mark Foreman CChem MRSC
Göteborg, Sweden
Reference
1 J Wang et al., Nat. Energy, 2017 (DOI: 10.1038/s41560-017-0033-8)
Christmas clear out
It was nice to read the ‘Santa’s little helpers’ letter in the December issue (Chemistry World, December 2017, pXX). With eight individual labs within the Technology Innovation Centre at Strathclyde University, the end of year shutdown activities are an important part of my year.
I usually get all the PhD students and postdocs involved and, as far as possible, try to make it fun. It’s a good way to promote some ownership of the facilities we all have to work in together. Renewing chemical inventories, clearing out fume hoods and disposing of all those unlabelled samples accrued throughout the year is just a selection of the myriad of tasks involved in the process. Afterwards, we can then all proceed to the pub together for some festive beverages in the knowledge that the labs are tidy and organised for a fresh start in the new year.
Thomas McGlone MRSC
University of Strathclyde, Glasgow
Phosphate or phosphide?
The On the spot puzzle in January’s issue (Chemistry World, January 2018, pXX) featured a shipment of ‘aluminium phosphate pesticides’ becoming wet. The article referenced a toxic gas being liberated – but aluminium phosphate does not undergo this reaction. The pesticide in question is aluminium phosphide, which releases phosphine when wet, hence its devastating effect in the rodent gut when ingested.
Brian Price CChem MRSC
Weston-Super-Mare, UK
Editor: Good spot. Many other readers also identified this mistake, and we apologise for the error.
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