Post Tagged with: "Science"

Homeopathy: Science or Sympathetic Magic?

As a new contributor to Chemistry Blog, I’ve decided to ‘break myself in’ by tackling the somewhat controversial and thought-provoking topic of homeopathy.  As I write, we find ourselves part way through ‘World Homeopathy Awareness Week’, so the subject is enjoying quite a high profile and twitter seems to be alive with discussion on the matter.

 

Before I go further, I feel I should declare myself to be a sceptic.  I’m doubtful as to whether any other point of view on this subject would be published on Chemistry Blog –so that will come as no surprise.  After completing my chemistry studies, I chose a career in the pharmaceutical industry –to make a difference.  I also rely on daily medication to manage my own condition.  I’m therefore very aware of the difference proven chemistry can make to the quality of people’s lives.  The science of drug development is founded on proven facts; a great deal of money, effort, time and hard evidence is required for just one new drug to reach the market –I will return to this subject in a later article.

 

What are the principles of homeopathy?

 

Homeopathy is an alternative medicine, based on the principle of treating like with like.  Patients are treated with highly dilute preparations believed to cause symptoms in a healthy person, similar to those being experienced in the patient.  Commonly used dilutions are 10C and 30C.

 

To achieve a 30C dilution, the ‘active’ ingredient is diluted 1 part in 100 –and then a drop of this solution would be diluted to 1 part in 100 and so on for 30 repetitions.  The resulting final solution would be 1 part active in 1 followed by 60 zeroes.  To put this number in perspective; one molecule of ‘active’ in a volume the size of the entire observable universe would be 40C.  Homeopaths claim a process called ‘succussion’, the act of striking the vessel containing the solution against an elastic surface 10 times at each stage of the dilution process, activates the ‘vital energy’ of the diluted substance and they talk, not in terms of dilution, but in terms of ‘dynamisation’ or ‘potentisation’.

 

As chemists we know there is a limit to any dilution that can be made without losing the original substance entirely.  This limit is related to Avogadro’s number and in homeopathic terms roughly 1 part in 1024 –equivalent to a 12C preparation.  A 30C preparation would require giving 2 billion doses per second to 6 billion people for 4 billion years to deliver a single molecule of the original material to any patient.  It is worth pointing out here that homeopathy dates from a time predating the discovery of atoms and molecules, so it was a widely held belief that a substance could be diluted ‘ad infinitum’.

 

Homeopaths believe the more dilute a preparation is the more effective it is. They believe the diluent used (usually water) has a memory of the active molecule it once contained.  My professional life as an analytical chemist would be a living nightmare if this were the case and carefully prepared diluents were ‘remembering’ the properties of the all the compounds they had contained.  Just imagine what the HPLC chromatograms would look like!  There would simply be no point in trying to keep the equipment free from contamination.  The notion of ‘molecular memory’ is at best implausible; it suggests the shape of a molecule is more important than its chemistry. Putting reason aside for a moment and accepting that water has memory –how would it emulate the chemistry of that molecule?  That very notion would require our current understanding of chemistry to be re-written and that understanding has provided us with thousands of medications which have been proven to be effective.

 

Clearly, if homeopathy achieves a successful clinical outcome, there is something else at work here. There is likely to be a significant ‘placebo effect’ and there is anecdotal evidence to support this idea. Also, the act of consulting the homeopath and the attention and sympathy the practitioner gives the patient –is believed to support the healing process. This, however, can be dangerous when the practitioner advises the patient against engaging with conventional medicine –this can, and has, resulted in tragic consequences.

 

As a complementary therapy, homeopathy appears to benefit some and as such it has its place in modern medicine. It isn’t sensible to use it as the only course of treatment for any condition, especially not a serious disease. The ‘science’ doesn’t stack up -it’s just sympathetic magic.

By April 12, 2012 15 comments general chemistry, opinion

How Water Freezes Lower on a Negatively Charged Surface

I first heard this on National Public Radio and then I searched for it. In short, David Ehre, Etay Lavert, Meir Lahav, and Igor Lubomirsky report in Science, (Water Freezes Differently on Positively and Negatively Charged Surfaces of Pyroelectric Materials) water freezes at a lower temperature (-18°C) on the negatively charged side of a lithium tantalate plate with a strontium titanate film than on the positive side (-7°C, and -12°C uncharged).

Is this unique or is this a manifestation of something in our standard introductory organic chemistry textbooks? I thought it was the latter. Let me explain how.

For the purpose of thinking about this problem, let us assume the metal surface is simply a flat charged surface, without contour. If the surface has a negative charge, then the water should be attracted like a flagpole. One hydrogen should be anchored to the surface of the metal at right angles and the other hydrogen could spin about that axis with the flag hydrogen at 105°. It should not be surprising that this configuration should not be as good of a surface as one with greater rigidity.

If we compare with the positively charged surface, then both pairs of non-bonded electrons should be anchored to the surface and locking the hydrogens in a fixed position. This should limit the degrees of freedom and enable crystal growth.

For those that may be wondering where this is found in your textbook, it may not be there. The negatively charged surface is the one that seemingly will have the most important stereochemical constraints and information in a textbook. The analogy I was comparing is the stereochemical restrictions of proton transfer reactions. In that context, the angle between a proton and donor-acceptor electron pairs in a hydrogen bond is usually 180°. One can find smaller bond angles in intramolecular proton transfer reactions, such as the decarboxylation of a beta-ketoacid or a Cope elimination reaction of an amine-oxide as six and five-membered ring examples.

You may also encounter a … transition state which transfers a proton via a four-membered ring. While this mechanism is present in some textbooks, I am troubled by a lack of precedent for this proton transfer. In a normal hydrogen bond, the preferred bond angle is 180°. Variations from 180° are commonly found in six and five-membered rings …

While the four-membered ring is expedient and avoids a zwitterionic intermediate, I am skeptical sufficient experimental data exists to support it. In the normal hydrogen bond, the electron-electron repulsion forces the nuclei to be linear.  While smaller angles are present in six and five-membered rings, a continued decrease in bond angle increases the electron-electron repulsion exponentially as predicted by Coulomb’s Law. This could be compensated for with a large nucleus…. A larger nucleus can attract electrons and mitigate their repulsion. However, I have resisted writing any examples of proton transfers via four-membered ring intermediates. [A Handbook of Organic Chemistry Mechanisms, p 65]

I could have drawn a model with two attachments points for water. That would probably look better if a plane charged surface is present rather than several pairs of electrons. If a two point model were to be present, then another model for the melting point difference is needed.

P.S. this is my first post here. As I often seem to think of something bleeding edge, not obvious, heretical, or downright wrong, I hope if there were any comments, this is just an idea. I may change my mind tomorrow.

By February 10, 2010 3 comments science news

Breaking Stuff for Science

Most chemists will agree, a chemical spill on the floor is one of the most annoying things to have to deal with in a lab. With LBL policy, you have to adhere to the SWIMS protocol: Stop work, Warn others, Isolate the area, Monitor yourself, Stay in the area. Not to mention using the correct spill kit, dealing with all the paperwork of the spill and the opening of the spill kit, explaining to the safety people what happened and why (hopefully) it wasn’t your fault, etc.

Aside from making sure your people are competent and well trained, not much is often done to prevent spills. Engineering controls such as secondary containment, fume hoods, capped reagent bottles, etc. work well when people remember and plan to use them. All too often, we see good chemists forgo extra safety steps for speed or just plain old laziness. Sometimes, people get badly hurt not because they were bad chemists or bad scientists, but because they really needed to catch the 6:40 train that day.

What we need are more safety devices that prevent the accident caused by a failure of the preventative safety measures from being very dangerous. For example, take these safety-coated reagent bottles from VWR. They have some plastic coating (PVC I think) outside of the glass to prevent spills even if the glass shatters. Sure some solvents would eat through the coating, but it would still buy you time to contain the spill, or evacuate the room if necessary.

Recently, with LBL’s current safety kick, our lab ordered 40 of these babies to replace our older reagent bottles. Interestingly though, the coating is really hard to see. In fact, when we first examined the bottles there was a dispute between some lab members as to whether we received the correct shipment or not.

Student Scale

Here is how the bottle looked, next to a typical graduate student size scale:

Being scientists however, Mitch and I knew that we couldn’t just take VWR’s word that we now had safety-coated reagent bottles.  We needed to test whether it really had the safety-coating, whether the coating would actually stay intact after an impact strong enough to break the glass inside, and whether the coating would feel weird if we poked with our finger.




Saftey first!


So, using my safety training, I put the reagent bottle into a plastic bag, and put the plastic bag inside a phototray. Note the secondary and tertiary containment.


Its curtains for you bottle!



I went and found a big wrench, donned my safety goggles, lab coat, nitrile gloves and put the soon to be destroyed bottle durability testing apparatus into a fume hood with the sash half open.  I then proceeded to smash it to pieces. It was a good day of science.





Moden laboratory art

Here is the result after a good beating. The safety-coating is quite clearly visible now, along with the area where the hole would be, if the coating wasn’t still covering it. The interior glass shattered as expected, but the safety-coating simply flexed a bit and recovered. Also, no sharp pieces of glass pierced the coating, so the contents of the bottle would have been contained. It took a significant amount of effort with some sharp tweezers to illustrate the intact film of the coating. We also confirmed our hypothesis that poking the film with our finger would feel weird. The bottle met our expectations in all tested categories. It also looked really cool and took a great picture.

Always dispose of your waste properly!

So in our effort to make the lab safer, we tested and confirmed the usefulness of these safety-coated reagent bottles in an easily repeatable scientific experiment. Tests would have been done in triplicate, however funding was abruptly cut off when we attempted to share our findings with others in the lab.  We recommend the safety-coated bottles for use throughout the chemistry lab. All waste was disposed of in coordinance with EH&S protocol.

By June 16, 2009 3 comments fun, materials chemistry, Uncategorized

32-electron chemistry

We all remember learning about octets and valence electrons in school. We may also remember the first time we saw an 18-electron transition metal complex. This week Dognon et al. discuss the possibility of 32-electron organometallic complexes.[JACS] In order to reach 32-electrons, f-orbital participation is essential. Below is a picture of a hypothetical organometallic complex with 28 carbons in a cage around an actinide element.

An@C28

 

Although these systems are not new, as the Smalley group made U@C28 in the gas-phase in ’92,[Science] Dognon et al. examine a series of these systems for different actinides. The major conclusion is that the plutonium system is theoretically predicted to have the largest bonding energy for its Pu4+@C28 complex. Since fullerenes and the intercalation of metals often only need heat to be synthesized, I wouldn’t be surprised if these complexes have already been made but missed as impurities and byproducts.

Link to paper: A Predicted Organometallic Series Following a 32-Electron Principle: An@C28 (An = Th, Pa+, U2+, Pu4+)

Update 1: Jyllian Kemsley also covered it at C&EN — Stable Caged Actinides Proposed(subscription)

Mitch


By December 7, 2008 1 comment nuclear chemistry, theoritical chemistry