general chemistry

#ChemMovieCarnival: Testing Breaking Bad

I can’t believe  no one else has grabbed Breaking Bad for the Chemmoviecarnival.

In case you don’t know its a show about a high school chemistry teacher, called Walter White, who turns his talents to the production of  methamphetamine in an attempt to subliment his measly teacher’s income. In the course of the show Walt deploys his encyclopaedic chemistry knowledge to get him and his dopey (in more ways than one) sidekick out of a few sticky scrapes. They make a battery to jump start a RV, dissolve bodies with HF, prepare ricin to dispose of his enemies and so on.

There’s plenty of neat, and reasonably  accurate, chemistry in the show. But do Walt’s various solutions (pun intended) really hold up to scrutiny? I thought I’d have a go at putting some of them to the test . Fear not, I haven’t started a meth lab in my garage. Instead I tested the scene where our (anti) heros use thermite to melt through a lock.

Here’s my set up. A nice tube of thermite sitting on top of a locked padlock.

 

Fire in the hole!

And its not looking good for the padlock. All that molten iron can’t have done it much good.

But after everything has cooled down….

One intact padlock! It won’t open, because I think the locking mechanism  has melted, but it would certainly keep a door locked.

So I guess that’s a chemistry fail for Walt and Breaking Bad. 

p.s. I think you folks over at Reddit might have taken me a whole lot more seriously than was my intent.

 

By April 21, 2013 4 comments entertainment, fun, general chemistry

Is ‘Chemical-Free’ Nonsense?

Back in 2008 the UK’s Advertising Standards Agency (ASA) ruled that an advertisement for an organic fertilizer  claiming to be “100% chemical free” was not misleading because:

“When there is a colloquial understanding of a word, we can take this into account when reaching our decision. In this case, we believe that most viewers are likely to understand the term ‘organic’ as meaning no man-made chemicals have been used to manufacture, or are present in this product. For this reason, we believe that most viewers are unlikely to be misled by the claim.”

To many this seemed like a largely illogical statement, including the Royal Society of Chemsitry. Their  response  was to offer a £1 million bounty for anyone who could present them with a truly 100% chemical free material.

Five years later and needless to say  the RSC has not had to cough up. Meanwhile the term ‘chemical-free’ is still being banded about (including articles in mainstream media(chached page) , eliciting periodic complaints and some highly amusing satire  from bloggers (and not just the chemistry crowd, a Mum’s blogs have joined in as well). In short not much has changed.

I figured it might be time to see if the ASA might reconsider it’s position. And a brand of ‘chemical-free’ deodorant that’s stocked in Holland and Barrett (a health food shop in the UK) seemed like the perfect test bed. I completed the ASA complaints form, making all the usual points about how it can’t possibly be chemical free, and this is the response I got.

While we appreciate your point that all material consists of chemicals, there do not appear to be grounds to suppose that this means that consumers will be misled by the claims in this ad.  We note that the claim is qualified by a list of ingredients next to the product description.  We consider that consumers are likely to generally interpret claims such as this in the practical sense that no synthetic chemicals, as opposed to the organic constituents of the product, have been added to the product rather than in the literal sense that the product includes no chemicals whatsoever.

On this basis we are satisfied that consumers are unlikely to be misled to their detriment by this ad and that the advertisers are not in breach of our Code on this occasion.

So pretty much the same stance they took 5 years ago, which does rather grate. But does it really matter? Maybe the consumer does understand that “chemical-free” is nonsense and  I should stop getting irritated by it.  The comments in the Smartmama.com blog seem to back this up: The general feeling seems to be  an understanding that shampoo etc.  can’t be ‘chemical-free’ , combined with annoyance at products that use the term. One particular comment sums it up nicely..

Could anyone be more contemptuous of the public’s intellect than people marketing “chemical free” products?

Seems like “chemical-free” marketing might be backfiring. Let’s hope so.

 

 

By April 6, 2013 14 comments general chemistry, Uncategorized

Great Show But Was the Chemistry Quite Right?

A guest blog post by Dr Nigel Young, an inorganic chemist at the University of Hull.

I have just watched the first of the 2012 RI Christmas Lectures entitled “Air: The Elixir of Life”  by Dr Peter Wothers on BBC4. Whilst there were many excellent demonstrations and explanations (some of which I may make use of) and it is very good to see chemistry portrayed in an enthusiastic manner I am a little concerned about the way that chemical bonding was dealt with which was confusing, and almost certainly incorrect. He had a terrific contraption representing a diatomic molecule, and by adding electrons into a holder between the atoms they got pulled together to represent bonding orbitals. When electrons were put into anti-bonding holders the atoms moved further apart. This all sounds fine, but the alarm bells began to ring  when the consequences of considering that there are both 2s and 2p electrons/orbitals involved in the bonding were ignored, and especially the fact that the bonding and anti-bonding orbitals derived from the 2s set are filled before getting to the 2p ones. The approach used in the programme predicts that Be2 has a considerable bond energy/strength as it has four bonding electrons, whereas experimentally and computationally it is very weakly bound if at all, and this is because it has an equal number of bonding and anti-bonding electrons. It was also stated that C2 has the strongest bond energy, whereas amongst the diatomics this is found for N2. He seemed to show a chart of increasing bond energy/strength from Li, through Be, B to C and then decreasing to Ne,  but this does not seem to correlate with other available data. The high carbon bond energy was then used to explain the hardness of diamond, but what about the slipperiness of graphite? Simplifying concepts is certainly necessary in these sort of activities, but presenting an inaccurate picture and more importantly an erroneous prediction of bond strengths seems less than ideal. It seems to me that this has suffered from the over use of hybridisation (which in general is a bad way to explain bonding) and  lack of understanding of molecular orbital theory (which is a much better way to explain bonding, although admittedly there is the complication of explaining the difference between the ordering in O2 and N2) which has been compounded by extrapolating from diatomics to solid state compounds.

Did no one else spot this?

UPDATE. Posted by Mark:

Peter Wothers has very kindly taken the time to explain his thinking behind his model.

Having come up with this idea of a model, perhaps I should clarify.

What I was trying to get across was the idea of bonding orbitals and antibonding orbitals. The confusion comes from the model suggesting that it ONLY refers to diatomics whereas the data in the chart is for essentially the enthalpy of atomisation of the period two elements in their standard states. The graph used real data which clearly shows carbon with the greatest enthalpy of atomisation. (As an aside, let’s not forget graphite is not slippery in a vacuum!)

Of course the simplified diagrams given in the diagrams quoted are approximately correct for diatomics, but the picture is more complicated for solid states when band theory would provide a better starting point. However, whether in solids or diatomics, the idea that some electrons help to bond atoms together whilst some actively pull them apart is a key one which the model tried to illustrate. This is not an idea commonly met with at schools.

Personally, I would not go into hybrid orbitals, but in order to understand the bonding in the standard state of the elements lithium to fluorine, we should use the 2s orbitals and three 2p orbitals. The maximum bonding is reached for carbon since each carbon atom supplies enough electrons (4) to the bulk to fill completely the bonding levels this was what the bonding model was meant to show.  Sadly, this clearly misled since some people thought it was talking about the bonding in C2 molecules.

I accept that the model is not perfect (how could it be?) but I personally thought it better than “dot and cross” diagrams and might introduce young students to a new idea.

Sorry if it’s confused people instead.

Peter

By December 27, 2012 6 comments general chemistry, Uncategorized

Life in Chemical Development, Part 3.

The last part of the trilogy: In the last two  I wrote about my first impressions as a chemist in chemical development blessed with a late stage project involving some azide chemistry. This project continued when I received a message that it was actually going into production. In the meantime all the use tests1 I had carried out bore fruit and we were able to define three suppliers for the benzyl alcohol and registered it as the starting material for the drug substance manufacture. So now I only had the synthesis of the benzyl chloride and its conversion to the azide to worry about.

Due to lack of capacity in chemical production it was decided to outsource these two steps to an external manufacturer and after a series of meetings with this particular company we went to their facilities to work with them in carrying out a pilot scale series so that they could get to grips with the chemistry. So off we trundled (the production chemist and I) to spend ten days or so to familiarise them with the chemistry.

We spent the first morning just finding the place, the taxi driver got lost! Ending up back at the hotel I decided to rent a car and eventually found the site. After discussing the chemistry in depth they decided to run the first 1 kMol reaction. Off they went and we disappeared back to the hotel to get some decent food and wait for a phone call. Five hours reaction time came and went, no call, so off we went back to the plant. The place looked suspiciously quiet, I thought “Oh dear” (to put it politely) something has gone wrong. We eventually found the responsible chemist wandering around in front of the building, shaking his head and mumbling to himself, and tears were streaming down his face. Obviously he had been exposed to the physiochemical properties of the benzyl halide. Indeed he had! We followed him into the pilot plant, wearing gas masks and there it was, the source of his mumbling. They had used an “old” reactor. The enamel was cracked (history does repeat itself) but this time the crack was larger and the 37% hydrochloric acid had merrily eaten it way through the reactor and into the cooling coils. Of course they shut the whole thing down, upon which the whole mess solidified. Scratch one reactor. Well we went home leaving them to it. I do not know how they disposed of the mess, and I don’t really want to.

Some weeks later we were back. They were ready to have a second go at it. This time it worked. During the five-hour reaction time I took a wander outside and started crying again. The room beneath the reactor was open to the world. I went in and saw an open bottle of ammonia directly under the valve in the bottom of the reactor. Looking up I saw a steady drip of the benzyl halide emerging from the valve. Pointing this out to the operator he was not bothered at all and said that ammonia was good for the lungs and anyway not a lot was being lost. But the reaction worked as advertised, as did the azide step. So we returned home and gave them the outsourcing work.

Months later we returned to their state of the art production facility. A rather large building containing safety boxes, each with two floors the upper one with two 10 m3 reactors and beneath centrifuges and pressure filters etc. There were four such boxes on each side of the building that was only about three years old. The control room was at the entrance end and everything was computer controlled, apart from adding the reagents manually which needed a human being! So this was quite a scale-up, about 15 times but far as I remember I think we did 12 kMol batches.

Before we started we had a look at the safety box we were going to use. For some reason this had all the glass tubes for the exhaust gases ziz-zagging up the walls, presumably to save space. One of them was full of a liquid with a very light greenish tinge. After several enquiries I was told it was hydrochloric acid remnants from the cleaning process. Well as we were going to use hundreds of kilos of dusty sodium azide I insisted the liquid was removed. This put the schedule back and we actually began the next day with the chemistry.

Off we went with the synthesis of the benzyl chloride. All went well until the operator tried to transfer the product to the other reactor. The technician could not put more than 0.5 bar nitrogen pressure on the reactor to get the transfer going. He kept trying to increase the nitrogen pressure, no luck, so I suggested he should go and look. No response. So I ambled along and peered in the porthole. Wow, it looked like Old Faithful. The product was being pushed out of an inlet port of the reactor with the nitrogen pressure. The stream was about 2 meters high. So I sauntered  back to the control room and told them this. Off went the nitrogen pressure on went the gas masks and safety suits and we went along to the box. It turned out that the operator who removed the pH electrode had not replaced the cap properly hence causing the geyser effect. I went back to the hotel so they could clean up the entire mess. The next day we started again. This time all went well and we were able to produce both the halide and the azide and obtained the required yield. That was I thought.

It was all quiet on the western front when the phone rang again, yes the second time it rang. There was a nice voice on the other end and we were having a pleasant conversation until the word INSPECTION was uttered. A mock FDA inspection was planned for Monday next week and did I have time to attend? This was Wednesday. Did I have a choice? No, came back down the line. This was a three-day event run by our internal QA, who at some time and no doubt considerable expense had poached a FDA inspector. So I examined the SOP telling me what to do in the event and spent the rest of that week getting the house in order. The great day arrived at last and I packed all my folders and computer into the car and took off for the meeting site.

An enormous empty room greeted me. I was always early for meetings so I could drink all the coffee and eat the small sandwiches provided or snaffle all the ones I liked. People commenced arriving and the room started filling up with conversation, computers and grey A4 folders. The production chemist arrived accompanied by two mammoth shopping trolleys full of these folders, I don’t know where the trolleys came from but they were full to overflowing. In rolled the tame ex FDA inspector followed by his minions and got the meeting started.

As it turned out they were interested in everything except the chemistry. The production validation protocols were examined in minute detail, as were the analytical methods and their results. Cleaning practices, labelling procedures, Sop’s, calibration, you name it, it was examined, but not the chemistry. They probably even looked to see if the toilet paper conformed to cGMP, but still no chemistry. Finally on the last day chemistry reared its ugly head! “Did you examine your starting material for the existence of positional isomers and other elements (those related to the ones we had in the drug substance)?” Some kindly neighbour kicked the chair from under me where I had been happily dreaming about seaside holidays. “Yes and yes”, I said after picking myself up off the floor. “Good, good” said the fake inspector and turned back to giving the analytics guy round 15 of his version of the Spanish Inquisition. I went back to sleep. During a waking period I did observe that some of the questions they asked were silly to say the least, but I suppose he was only earning his big bucks. Still it was an interesting few days and I learnt what not to do.

Some months later I learnt that we (the company) had sold it lock stock and barrel to someone else. They of course visited us and carried out an inspection, more or less as above. I did not attend the meetings but was available should chemistry expertise have been required, but I wasn’t needed. That was that for me. I went back to the lab and cleared out all the samples and archived all the folders. Where they are now I don’t know, buried under a foot thick pile of dust I suppose. A happy end to my first large project

Notes:

1      A use test is employed in order to investigate material from potential starting material suppliers: The compound must meet the given specifications and perform in the series of reactions to deliver the desired product according to its specifications.

p.s.

After all this I have come to the conclusion that cGMP does not stand for “current Good Manufacturing Practice but Grosse Mengen Papier (translated from the German it means large quantities of Paper).