From Richard Schmidt
From Richard Schmidt
Horst Hippler asks why most natural amino acids are l and most natural sugars d (Chemistry World, October 2006, p22). The answer to this question might already have been answered: selection for these enantiomers has been driven by a fundamental property of interfacial (or vicinal) water. Philippa Wiggins provides a lucid account in an article entitled Water in complex environments such as living systems(Physica A, 2002, 314, 485). She explains that water at an interface comprises microdomains of ’high density water’ and ’low density water’. These are in effect different liquids in which a given solute (eg d-glucose or l-glucose) exhibits different solubilities.
In essence, the water environment at an enzyme surface favours one enantiomer over the other. This same article also seems to provide an explanation for the distribution of Na+and K+ions in living systems. Thus, the intracellular vicinal water environment favours high K+ ion concentrations and low Na+ion concentrations.
In exploring this concept further, we may also begin to speculate as to the mechanism of the toxicity of Na+ions in a high sodium diet and hence begin to understand why a diet rich in K+ions (provided by fruit and vegetables, wine, milk, etc) can be protective in those whose metabolic characteristics render them susceptible to the damaging effects of a diet high in salt. This fundamental property of vicinal water would appear to provide the basis for a compelling and unifying hypothesis that can at the same time throw light on the origins of life and on the mechanism underlying many of the commonest diseases currently taxing the health systems of the so-called developed world.
R J Schmidt CChem FRSC
From Paul Board
Interesting to note M Saiful Islam’s comment on how Michael Faraday ’should still be on the ?20 note’. (Chemistry World, December 2006, p24). Coincidence then that in the same issue (p88), Flashback featured Faraday’s ’usurper’, Edward Elgar, who will also shortly be replaced on the back of the ?20 note (by Adam Smith).
Elgar was a keen amateur chemist, and Flashback mentions his hydrogen sulfide apparatus. Readers may also find the following recollection of a minor chemical catastrophe by Elgar’s friend and leader of the London Symphony Orchestra Billy Reed of some interest:
’One day he made a phosphoric concoction which, when dry, would "go off" by spontaneous combustion. The amusement was to smear it on a piece of blotting paper and then wait breathlessly for the catastrophe. One day he made too much paste; and, when his music called him and he wanted to go back to the house, he clapped the whole of it into a gallipot, covered it up, and dumped it into the water-butt, thinking it would be safe there.
’Just as he was getting on famously, writing in horn and trumpet parts, and mapping out wood-wind, a sudden and unexpected crash, as of all the percussion in all the orchestras on earth, shook the room, followed by the "rushing mighty sound" he had already anticipated in ’The Kingdom’. The water-butt had blown up: the hoops were rent: the staves flew in all directions; and the liberated water went down the drive in a solid wall.’
Elgar also wrote of his attempts at making soap and his attempts at getting his daughter to try it out:
’I am resuming chemistry and made soap yesterday between fits of scoring (not scouring!) the symphony. I have been vainly trying to persuade Carice to wash with it - strange how little encouragement I get!’
P Board CChem FRSC
From Khalid Maqbool Siddiqui
Chemistry used to be a dead subject here in Pakistan, but it has suddenly woken up with an almighty roar. There are announcements on the television and adverts in the newspaper that science Olympiads are going to be held in Russia in 2008; those students who wish to participate need to submit their application form to the respective organising bodies. The Olympiad science subject list includes mathematics, chemistry, biology and physics. Surprisingly, about 85 per cent of students have opted for chemistry. This is seen rarely in Pakistan, but the work and efforts of the RSC in trying to popularise and advance the chemical studies around the world have certainly paid off. This is clearly reflected in the enthusiasm of the students in Pakistan who are opting for chemistry in large numbers.
We all hope that the work the RSC is doing continues to be as extraordinary as it is now and that we see many developing countries like Pakistan come up with such interest in chemistry.
K Maqbool Siddiqui AMRSC
From Michael Saxby
I was interested to read about the ’lightstruck’ off-flavour in beer Chemistry World (November 2006, p34) because I was the editor of a book entitled Food taints and off-flavors published in 1996.
Chapter 10 dealt with off-flavours in alcoholic beverages in which the author, S Bennett, noted that light can cause deterioration of beer. I was therefore pleased to read that the cause of the problem has been solved but sad that the actual compound was not named. I then remembered that Helen Fletcher had reviewed an earlier paper (Chemistry World, August 2004, p16) in which the compound responsible had been identified as 3-methylbut-2-ene-1-thiol, also known as ’skunky’ thiol.
May I make a plea that authors check earlier publications on the same subject to which we can refer for additional information?
M Saxby CChem FRSC
From Robin Sheppard
The issue of energy sufficiency is exercising the minds of many scientists and politicians. There are many potential solutions for fixed (static) energy provision such as nuclear power, clean coal technology, wind power, and wave and tidal energy, as well as the obvious savings from energy conservation.
There is also the recent development in photovoltaics which holds the tantalising promise that the pay-back time for solar cells could be reduced from 20 years to under a year, (Chemistry World, October 2006, p14).
However, for road transport the options are fewer and much less developed. There are some salutary facts concerning the amount of land needed to grow significant quantities of liquid fuels from conventional crops (Chemistry World, November 2006, p39).
Despite this dose of reality, there is an alternative source of lipids, which can be readily converted to biodiesel, but without competing for arable land. The ’crop’ concerned is algae, some varieties of which can produce as much as 50 per cent of their dry weight as lipids.
An interesting detailed examination of this possibility has been carried out by Michael Briggs of the University of New Hampshire, US.
Although we do not have huge quantities of sunshine in the UK for the photosynthesis of algae, algal growth where it is not wanted in ponds, pools and lakes is only too common. Perhaps manufacturing fuel from algae could help the UK to meet its carbon emission targets.
Regarding the economic competitiveness of liquid biofuels, this would be greatly improved and simplified if the government converted its fuel duty to a straight tax on net carbon emissions, but no doubt the UK Treasury in its usual myopic way would block this straightforward measure.
R Sheppard CChem MRSC
South Glamorgan, UK
From Norman Nicolson
The feature entitled Old King Coal reminded of what used to be common practice (Chemistry World, November 2006, p48). If air and steam are passed through red hot coke, a mixture of CO, H2 and N2 results. This was called producer or synthesis gas and was used to make ammonia, methanol and hydrocarbons or was added to the town gas being made.
The current gasification of coal to syngas, to run a combined cycle plant, could be modified to use the waste steam produced by the plant to produce more hydrogen to enrich the syngas.
N Nicolson CChem MRSC
From John Murrell
Casper Schutte and Jan Boeyens say that they would have liked to work with Linus Pauling in order to persuade him not to explain the tetrahedral carbon atom by quantum mechanical hybridisation (Chemistry World, December 2006, p24). We need to be more precise about the word ’explain’.
In the early 1930s the ideas of the chemical bond focused mainly on electron pairing; this came from Heitler and London’s description of H2, itself taken over from ideas of G N Lewis. So, in this context what needed explaining was why the stable form was CH4 and not CH2, which might be anticipated because the ground state of carbon has two unpaired p electrons.
It was probably Pauling who first said that promoting an s electron to a p orbital requires energy, but this is more than compensated for by the energy gained in forming two more bonds.
The next step is to ask why CH4 has four identical bonds; or perhaps asking what we are implying by those four lines that we draw from carbon to the hydrogen atoms. In the electron pairing model we need to couple the hydrogen s orbitals with four equivalent carbon orbitals; hence the need to invoke sp3 hybridisation in the electron pairing model.
Most teachers would now explain why CH4 is tetrahedral rather than square planar by referring to electron pair repulsion, but the energetics underlying this model are not always convincing. Schutte and Boeyens also attack Pauling’s concept of resonance, and again it depends on how it is used; but that is a longer story.
J Murrell CChem FRSC
From George Pitt
Dennis Rouvray’s interesting and informative article on obesity (Chemistry World, December 2006, p39) was slightly marred by the use of the calorie as a unit.
A calorie is, fundamentally, the amount of heat required to raise 1g water through 1?C.
When early nutritionists started using the calorie as a measure of energy they found it inconveniently small. So they introduced the large Calorie, written with a capital, which was 1000 real calories.
Unfortunately the important upper case C fell into disuse, so most of the population use ’calorie’ when they really mean ’kilocalorie’.
All reputable nutritional journals use kcal; so should all other reputable scientific journals.
G A J Pitt CChem FRSC
From Tom Stevenson
David Phillips’ appreciation of the life of Charles Rees made me sorry not to have known him (Chemistry World, November 2006, p15). As a student at Imperial College London between 1971 and 1977 I had no recollection of Rees. All was made clear by a check on his Who’s Who entry; he did not arrive at Imperial until 1978.
T Stevenson CChem MRSC
East Horsley, UK
Ed: We have checked the dates and Charles Rees did indeed start at Imperial College London in 1978, not 1970 as stated in the obituary.
From Gail Giltner
It would be interesting to determine the number of individuals that have benefited from Merck’s drug Vioxx versus the number that were injured. [Vioxx is a non-steroidal anti-inflammatory drug that was developed to treat osteoarthritis and acute pain conditions. In 2004, Merck withdrew the drug because of concerns about the high risk of heart attack and stroke associated with long-term, high-dosage use.]
Vioxx has benefited many people that I know, my husband being one of them. It would be nice to see Vioxx return to market with restrictions on who could receive the medication. It seems that more testing has been done on the risks associated with taking Vioxx.
Being a nurse I know many people who have benefited from receiving this drug and because they knew they were not going to be able to obtain any more they saved the Vioxx that they had for times of absolute need. They understood the risk associated with taking Vioxx, but for them the relief from pain far outweighed the risk associated with taking the medication.
From Roger Lintonbon
In all the media hype about carbon emissions I have seen no reference to natural mechanisms that remove carbon dioxide from the atmosphere. As chemists, do we dare to suggest that the deposition of calcium carbonate in the ocean via the shells of dead organisms from algae to molluscs to coral reefs buffers the discharge from the combustion of fossil fuels? The calcium carbonate/calcium ion/carbon dioxide equilibrium is, after all, a dynamic one. All the carbon bound up in the vast deposits of chalk and limestone was once in the atmosphere having been discharged by volcanic activity but it seems to be our own secret which we are afraid to share. Should we not challenge the doom mongers with sound scientific knowledge and, incidentally, attract youngsters from environmental studies to unfashionable chemistry?
R Lintonbon CChem MRSC
From Gerry Moss
Brian Wood need not be worried about the loss of acetic acid as a name (Chemistry World , November 2006, p39). The Iupac preferred name for it is acetic acid. For the aliphatic acids only two trivial names are retained, formic and acetic.
The change from propionic to propanoic and butyric to butanoic is so small that the Nomenclature Committee of IUBMB (International union of biochemistry and molecular biology) adopted the systematic name of these two acids for enzyme reactions years ago.
The amino acids were also mentioned as a worry. Let me assure him that these names are unlikely to change. For example it is usual to use for alanine the systematic name 2-amino-propanoic acid. However, under all normal conditions it should be 2-azaniumylpropanoate, a name which is rarely encountered. The trivial name is a very convenient way to cover the zwitterionic nature of the amino acid.
G P Moss MRSC