Letters: May 2021

Cloud-free distribution

As an octagenarian who has just received the second dose of the Pfizer vaccine, I was interested in the article on Asel Sartbaeva’s use of silica coats to stop vaccines spoiling at room temperature.

Many years ago I was involved in research into silica hydrogels to prevent cloudiness in lager beers when cooled. This led to the development of the commercial product Lucilite, which as far as I know is still in use today. This works by adsorbing the proteinaceous material that causes the cloudiness onto the silica, which could then be filtered out.

Although powderlike in appearance, these silica hydrogels contain up to 80% water. An alternative line of research showed that such hydrogels could be tabletted or extruded under pressure and dried if necessary, leaving the silica matrix intact and stable.

It struck me this could be investigated to see if such stable and inorganic silica hydrogels might be used as carriers to provide vaccines cheaply and safely to poorer parts of the world.

Tom Griffiths FRSC
Via email

Mineral plastics at war

Your article on mineral plastics reminds me of the work of the late Peter Plesch of Keele University, my former supervisor. There was a balsa wood shortage early in the second world war because of U-boats – threatening production of the Mosquito fighter bomber. He developed an alternative by gelling aqueous sodium alginate with calcium ions and drying out the resultant hydrogel. The program was a success but wasn’t needed as the B24 maritime bomber closed the mid-Atlantic U-boat gap. He then worked for Michael Polanyi at Manchester on synthetic rubber but was beaten to it by the much better funded Americans.

I guess the post-war imperative was to sell the customer olefin and polyester polymers but hopefully his work will be cited against modern patents.

John Cooper MRSC
Ayr, Scotland

Life with hearing difficulties

I am a person with hearing difficulties. Since the Royal Society of Chemistry (RSC) is trying to make chemistry more inclusive to people with disabilities I thought I should try to share my experiences in the hope that people with good hearing could understand the problem.

The first thing I thought was to suggest an experiment. Push your forefingers tightly into each of your ear canals and have someone talk to you at their normal volume. If you can still make sense of what is being said, then ask two or three people to speak to you at the same level and at the same time. Then try to imagine what it is like to be like that for 24 hours each day.

My hearing became problematic during my early 30s and I was among the early people to have a stapedectomy in Adelaide, Australia in 1974. I had a cochlear implant in 2019. They are still a bit of a mixed blessing and as far as I am aware the RSC does not offer help to use these digital aids, preferring instead to use social media for their communications.

There have been some remarkable people who have learned how to come to terms with their problems. Sir John Cornforth is the first chemist who I came across. He was fortunate that his hearing difficulty came after he had completed his formal education. He was also fortunate to have married a very selfless chemist who was prepared to subordinate her career to put him first.

There was another remarkable woman who became simultaneously blind and deaf and that was Helen Keller. She is reputed to have been asked which is the worse and to have replied that in her opinion it was hearing loss. She went on to say that blindness separates you from things, but hearing separates you from people.

David Hamon MRSC
Adelaide, Australia

Details, details

Reading Emma Pewsey’s piece on the importance of publishing full experimental details reminded me of a case early in my career. At the time in our group, the preferred method of carbonating a Grignard reagent was to pour it on to crushed dry-ice in a large flask (in one lot) to be worked up later, usually next morning. Most of our Grignards were in tetrahydrofuran (THF), and I was unaware that, apart from the sheer convenience of the method, it avoided the reaction of the intermediate magnesium salt with the reagent, which in THF is apt to give a ketone as the major product. In a paper, we just referred to ‘carbonation with CO₂’. This led to a pointed letter from another chemist.

I was also struck by the article by Chemjobber, which referred to nitrogen as an inert gas – which it usually is in organic chemistry. In my later career in industry, we were running a procedure in which the first stage was the reaction of lithium with triphenylphosphine, again in THF. Our final product was contaminated with hard-to-remove nitrogenous impurities. This was solved by changing to argon as an inert atmosphere. Nitrogen is definitely ‘ert’ as far as lithium metal is concerned!

Anthony Webb CChem FRSC
Via email

Wonders of the deep

In connection with the structure of hydrazoic acid, it is pertinent to recall another remarkable compound, unique among natural products, which has not enjoyed much publicity: 6-azidotetrazolo[5,1-a]phthalazine. This is the product of a toxic marine dinoflagellate, isolated in 1958. It has a unique tetrazole ring and a very rare phthalazine ring. The structure corroboration of this excessively rich (52.8%) in nitrogen compound came later.

A Varvoglis, MRSC
Thessaloniki, Greece

A dense mistake

The article ‘New magnesium alloy shows exceptional corrosion resistance’ says magnesium is widely used ‘due to its low weight …’. Low density please!

Dr Peter B Baker CChem FRSC
Prestwood, UK

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