Category Archives: Chemistry

Stupid Tricks with LN2

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One of my favorite tricks with liquid nitrogen (LN2) was to pour some onto a chalk tray at the bottom of a chalk board. The skittering, madly boiling liquid would entrain the chalk dust from the tray and transport it to the end where it would plummet to the floor making that wonderful muffled popping sound. The chalk dust would be splatted onto the floor where it would lie as a thin, mysterious white cake. I suspect the janitors were rather less delighted by this than I was.

Today’s youthful chemists, these tender shoots, probably think that dry erase white boards have been around since the time of the pilgrims. That’s OK.  I’ll not speak of squealing chalk, long leatherbound erasers, and chalk dessicated hands. The use of blackboards and chalk will remain our little secret.

Eat Venter’s Dust

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I gave a talk in a morning I&EC session last thursday at the Denver ACS National meeting. During an interlude provided by a no-show speaker, a member of the audience began to quiz down a hapless speaker who earlier presented on the filtration of plasmids. The gentleman’s concern was this- We are continuing to develop conventional processing technology while fellows like Craig Venter are devising step-change techniques for genomic analysis and synthesis. People like Venter have their names mentioned in the same sentence with “synthetic biology”.  Why do we bother with the more primitive methods of research when the real action is with folks like Venter?

The inquisitive fellow was asking a rhetorical question to all of us. But the point he skipped over was the matter of intellectual property. He kept asking why don’t “we” just switch the paradigm right now and use such technology? Why continue with highly manual R&D?  The problem with his question was in the assumption that Venter’s technology was something that “WE” have access to. Venter’s technology does not automatically translate into a community tool. It is more like an item of commerce. In reality, this will likely represent a major uptick in productivity to the financial benefit of the intellectual property owners and licensees and their stockholders.

How the scientific workforce will fare is a different matter. Increased productivity usually means reduced labor per unit of output. I suspect that Venter’s technology represents a higher entry barrier to those who want to be in the market.  It may be that the outcome will be a broader range of diagnostic and treatment services available to a shrinking pool of insured people able to afford it.

Is this as good as it gets?

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I’ve had this notion (a conceit, really) that as someone from industry, I should reach out to my colleagues in academia in order to bring some awareness of how chemistry is conducted out in the world.  After many, many conversations, an accumulating pile of work in ACS activities, and a few visits to schools, what I’ve found is not what I expected. I expected a bit more curiosity about how commerce works and perhaps what life is like in a chemical plant. I really thought that my academic associates might be intrigued by the wonders of the global chemical manufacturing complex and product process development.

What I’m finding is more along the lines of polite disinterest. I’ve sensed this all along, but I’d been trying to sustain the hope that if only I could use the right words, I might elicit some interest in how manufacturing works; that I could strike some kind of spark.  But what I’ve found is just how insular the magisterium of academia really is. The walls of the fortress are very thick. We have our curricula firmly in place on the three pillars of chemstry- theory, synthesis, and analysis. In truth, textbooks often set the structure of courses.  A four year ACS certified curriculum cannot spare any room for alternative models like applied science. I certainly cannot begrudge folks for structuring around that reality.

It could easily be argued that the other magisteria of industry and government are the same way.  Well, except for one niggling detail. Academia supplies educated people to the other great domains comprising society.  We seem to be left with the standard academic image of what a chemical scientist should look like going deeply into the next 50 years. Professors are scholars and they produce what they best understand- more scholars in their own image.  This is only natural. I’ve done a bit of it myself.

Here is my sweeping claim (imagine the air overhead roiled with waving hands)-  on a numbers basis, most chemists aren’t that interested in synthesis as they come out of a BA/BS program. That is my conclusion based on interviewing fresh graduates. I’ve interviewed BA/BS chemists who have had undergraduate research experience in nanomaterials and AFM, but could not draw a reaction showing the formation of ethyl acetate.  As a former organic prof, I find that particularly alarming. This is one of the main keepsakes from a year of sophomore organic chemistry.  The good news is that the errant graduate can usually be coached into remembering the chemistry.

To a large extent, industry is concerned with making stuff.  So perhaps it is only natural that most academic chemists (in my sample set) aren’t that keen on anything greater than a superficial view of the manufacturing world. I understand this and acknowledge reality. But it is a shame that institutional inertia is so large in magnitude in this and all endeavors.  Chemical industry really needs young innovators who are willing to start up manufacturing in North America. We could screen such folks and steer them to MIT, but that is lame. Why let MIT have all the fun and the royalties?  We need startups with cutting edge technology, but we also need companies who are able to make fine chemical items of commerce. Have you tried to find a brominator in the USA lately?

The gap between academia and industry is mainly cultural. But it is a big gap, it may not be surmountable, and I’m not sure that the parties want to mix. I’ll keep trying.

ACS Denver Last Day

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I’ve spent much of my time at the Denver meeting talking to vendors in the exposition.  There were some very good pieces of equipment at the show. One company had a GC the size of a sub sandwhich.  Pretty cool. It’s for on-site work and actually comes in Army green and camo. I wish I could remember the name.

The Agilent ICP/MS is truly amazing.  Sub part per trillion capability.  The system uses something called the “helium collision mode” to exclude polyatomic cations from the mass analyzer.  You know those pesky argon chloride cations from sample plasma, right?  The argon polyatomic cations can mimic heavier elements by virtue of their combined atomic mass.  The instrument has an octapole chamber with helium in it that serves to impede the larger polyatomic cations. Clever monkeys.

 

Denver ACS Meeting

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Just back from Day 1 at the Denver ACS meeting.  Spent the afternoon at the INORG session celebrating the 50th anniversary of the journal Inorganic Chemistry.  As usual, Harry Gray stole the show with his talk- today it was on oxo complexes. What I like about Gray is that he shows the younger members that being socially constipated is not manditory for success in chemistry.  Maybe it’s his delivery, but after a Gray talk I leave feeling like I have gotten a glimpse of the future.

Attendance is down a bit due to hurricane Irene.  Looks like the Atlantic coast dodged the bullet. Earth quakes, hurricanes … what next? Cane toads?

Bleaches and in-process checks of the enlightenment

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In his 1736 publication Smegmatalogia, or the Art of Making Potashes and Soap, and Bleaching of Linens, James Dunbar describes a process for the preparation of potash.  The intended user of the process was the common Scottish farmer. Dunbar was anxious to imbue the common Scot with the ability to “bleach” his own linens.  It is important to realize that the meaning of the word bleach in the early 18th century is different from contemporary use.  The modern use comprises notions of decolorization through oxidation of color bodies to produce a white appearance.  The 18th century concept involves the apparent cleansing and subsequent lightening of a fabric.

The book begins by detailing the preparation of a solution or extract from ashes called Lee.  To obtain this solution, the “Country-Man” would carefully collect Scottish vegetables such as the wood of oak, ash, beech, “thorns”, juniper trees, and “whins”. Suitable herbs included fern, breckens (or brackens), wormwood, thistles, stinking weed, and hemlock. 

Dunbar is careful to instruct that the vegetation should be burned in the shelter of a house but in such a way as to avoid burning down the house. The purpose of burning the vegatation in a shelter is to avoid having rainwater come into contact with the ashes.  My interpretation of this is that runoff carries away soluble potash.

The ashes are placed in a container and covered with water. The ashes are soaked in water until such time that the Lee “carries an egg on its surface”.  What Dunbar is telling us is that the extraction of the ashes needs to go until the worker obtains in the solution a particular specific gravity- this is a specification. There is some minimum specific gravity of the Lee that will float an egg.  And the higher the specific gravity, the more volume of the egg rises from surface of the Lee. The specification herein is required for the next operation.  In order to carry out a successful saponification of tallow, the Lee solution must be sufficiently concentrated. 

Dunbar then describes steps where the Lee is combined with the ashes of ash, beech, or fern followed by boiling the water off to afford “thickens of pottage“.  The residue is shaped into balls which are then calcined in a fire to afford a substance that may be stored in a dry container for the purpose of making soap. 

The discovery of chlorine in 1774 by Scheele and the subsequent of discovery of chlorine bleaching by Berthollet gave us our modern conceptual notion of bleach and bleaching. The develoment of bleaching powder was made by Scottish chemist Charles Tennant who took a patent in 1799.  Tennant’s associate, Charles MacIntosh, is thought to be a contributor to this invention.  Bleaching liquors and powders soon became an important raw material for the bleaching of paper and fabric.

The procedure described by Dunbar is a chemical process.  It tells the user when the extraction is complete, qualitatively at least, by a folksy means of specific gravity determination. This is really very clever- it uses a common object to do the test and the result is readily apparent.  Bleaching in the early 18th century involved the use of soaps and of urine treatment and bleaching fields- a far cry from what we now think of as bleaching.

Oil Well Torpedoes and Grubbin’ Stumps

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We tend to think of some things as being relatively new. I’m thinking of the gas and oil extraction technique of fracturing, or fracking.  In the 1884 third edition of The Modern High Explosives, Nitro-glycerine and Dynamite by Manuel Eissler, p 311, there is a mention of the practice of exploding nitroglycerine charges at the bottom of oil and water wells to renew or increase the flow. The author states that this is a popular technique in Pennsylvania at the time of writing.

On p 318 of the same book, Eissler describes the economics of blasting stumps. In general, the process of removing stumps was called “grubbing”. Enterprising fellows knowledgeable with nitroglycerine took little time in applying the explosive power of this oily liquid to clearing the land of stumps.  

Eissler describes the economics of explosive grubbing as follows:  Three pounds of No. 1 dynamite cost $1.50, labor cost 20 cents per hour, 25 ft of fuse cost 1 cent per foot, and 17 percussion caps cost 1 cent each.  Grubbing 17 oak stumps cost $22.52 with 99 man hours for chopping and piling the pieces.  Grubbing with an axe took 142 man hours and cost $28.40.  No. 1 dynamite was comprised of 75 % nitroglycerin and 25 % absorbent.

Bertholet’s discovery of potassium chlorate (oxygenized muriate of potash) happened in 1785. He observed

“that it appears to include the elements of thunder in its particles; and Nature seems to have concentrated all her powers of detonation, fulmination, and inflammation in this terrible compound”. 

Eissler goes on to say that attempts to prepare gunpowder or blasting powder with potassium chlorate lead only to loss of life and limb for the luckless experimenters with this compound.  Two of Bertholet’s artisans employed to do experiments with this material were killed in 1788.  The hazards associated with both manufacture and use of compositions of potassium chlorate were too great to allow this substance to see much commercial application by the 1880’s.

In praise of polyolefins

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Being a person nestled in the dark and humid recesses of industry, I find myself boggling at certain things out in the bright and sunny world.  Truly, it boggles my mind how little appreciation people have for polyolefin resins. That is to say, polyethylene, polypropylene and all the myriad copolymers and formulations found thereto.  Ok, let’s throw PVC and polystyrene in the mix as well.

Why do I boggle at this? What makes my head spin in puzzlement? I’m so glad someone asked.  Polyolefin films look innocent enough to be ignored. In their uncompounded state they are clear and colorless or they may be white.  Polyolefin films and extruded components are ubiquitous in packaging and thus are not normally an object of desire. They serve the object of desire. They occupy a lesser state interest in nearly all contexts.   They are made inexpensively enough to be torn asunder from the desired object and tossed wantonly to the side for later clean up.

But if the uneducated user of polyolefins only knew the extent to which modern science and engineering had been carefully applied to the lowly stretch wrap or the roll of 1 mil PE film. If they only knew the scientists and engineers who carefully devised the ethylene crackers to produce high purity ethylene, or if they knew the highly educated people who devise the polymerization process, they might have heard an account of the long march to produce water white films with properties matched to the end use.

Puncture resistance, elongation, fish-eyes, haze, modulus, crystallinity, glass transition temperatures, melt points, low volatiles, melt viscosity and strength- all attributes carefully tended to so that the film appears invisible to the consumer. High gloss, low haze films to make the product look even better.  Low volatiles and residues for food contact use.  Polyolefins engineered for specific densities for the global market.

All of the attributes above to attend to with a continuous polymerization loop that spews 50,000 to 80,000 lbs per hour of pellets into silos and rail cars. Pellets that will eventually go to converters who will blow films and extrude widgets all day long.  All so the consumer product can arrive at its destination wrapped unscuffed and free of dust.

Polyolefin materials are incredibly useful and amazing in their own right. We should have more appreciation for these materials and how they serve our needs.

Seeking simplicity in process scale-up

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My graduate school mentor use to say that you could synthesize anything if you had the right precursors. With enough clever reagent artistry, most small molecules can be assembled, though if only enough for an NMR spectrum.  With chromatography and small glassware, it is not unreasonable to do a few reactions on 1 mg of material and recover enough mass to get a proton and carbon NMR.  Yes, I know that with microfluidics and labs on a chip, much lower quantities can be handled. But I refer to getting your hands on enough material to see.

What most of us who came through graduate chemistry have learned is that there are enough acids, bases, protecting groups, oxidants, reducers, latent functionalities, and catalysts out there to choose from so that some combination should get you to an endpoint in your synthesis.  If not, then  NMR, mass spec, IR, and imagination (with ample hand waving) should at least give an idea of why something won’t work.

Reaction chemistry (not including biochemical transformations!!) can be thought to occupy two broad domains- 1) low temperature, ambient pressure transformations with highly reactive species (preferably named after dead chemists), and 2) high pressure, high temperature transformations with lower reactive species. Most chemists fresh out of school know the former better than the latter. And that drives our problem solving strategies: Finding reactive intermediates that will react between -30 C and 150 C with a 5 lb nitrogen sweep in a kettle reactor.

Sometimes, the dumber brute force approach is worth considering.  What can be done under pressure and at elevated temperature?  Or, what can be done at high temperature and short contact time?  That dusty Parr reactor sitting in the corner may be capable of a goodly bit of magic.  Behind a shield. It is good to visit the high temperature, high pressure world now and then. Of course, our engineering friends already know this.

As far as the search for simplicity goes, consider what merits there may be in thermally driven transformations. Every once in a while it may be a viable avenue for something useful. Try thinking of heat as a kind of reagent. Chemical plants are good at producing heat.