You are currently browsing the category archive for the ‘Chemistry’ category.

It is not uncommon to read in chemistry papers or hear speakers from academic institutions making the assertion that certain problems exist that their method or reagent may solve. Perhaps a particular catalyst may give rise to a set of useful transformations or said catalyst may be fished out and reused in many other runs. Or, maybe the reagent in development affords spectacular yields or stereoselectivity. Given that an industry might have blockbuster products that share certain features or pharmacophores, an efficient method for synthesizing that feature is likely to be of genuine interest.

Chemical research coming from an academic institution in the USA is almost always executed by students and/or postdocs. In the case of graduate students, the work is done as part of their degree program and is designed to achieve certain goals or to explore a question. Regardless, it is not done to achieve a commercial purpose with product sales in mind. Student research is conducted with training and publication success as the goal. Graduate success and publication are the work products of academics.

If it transpires that a particular academic wants to do work that is also of commercial interest, that work should include certain commercial sensibilities associated with chemical production. Every business has its own list of development criteria in use. It will have a basis on in-house equipment and skills, company policy, safety, economic imperatives, working capital, required profit margins, environmental permits, available economies of scale, specialty or commodity products, etc.

Adopting a new reagent for an existing chemical product can be very problematic for a business. For production pharmaceuticals, it is likely to be impossible for management to actually contemplate the trouble involved in changing an approved process. For other industries a similar problem exists. Changing a reagent in an existing process will likely require the customer to approve the change and the drafting of an updated specification. And, for their trouble they are going to demand a reduced price. I’ve received and given that talking to on a few occasions myself.

If the change is very early in the reaction sequence of a lined-out process, there may be a chance to do a replacement or change a step. Maybe. Remember that customers usually do not like change in regard to the chemical product they are purchasing. They want and need consistency. Even improving purity can be bad if it results in the final product surprising the end-user in some way.

I would offer that if an academic worker wants to make a difference in commerce, they should concentrate on the final product in the application. It may be that an existing product could be made cheaper by your wonder reagent, or perhaps some me-too congener. Your reagent may be superior in a functional group transformation, but that is likely to draw yawns. How does your reagent add value to a process in concrete terms?

By adding value I mean to say, increasing profit margins. Costs in manufacturing are broadly divided into raw materials, labor, cost of sales and other overhead. They are not all easy to minimize. For instance, a mature product may be priced according to commodity scale pressures. That is, there are numerous suppliers and low margins in the market for producers. If the cost of goods sold is driven strongly by raw material costs, unless you can wangle a breakthrough in raw mat prices, staying price competitive may involve a race to the bottom of the lake. However, if labor is the major driver of cost, you may have a chance to increase margins by reduction in man-hours per unit. That reduction would come from any of a number of labor saving strategies.

Labor savings can come in many forms. More efficient use of existing equipment can lead to an increase of capacity and throughput over the year if the turnaround time between runs is shortened. Process intensification can also increase throughput and consequently reduced labor hours per kg of product. Higher reaction temperatures benefit kinetics as do increased space yields by running at higher concentrations. Just beware of the reaction enthalpy per kg of reaction mass (specific enthalpy). It is very possible to over-intensify and bring on problems with safe operation and side reactions.

For the academic aiming to be technologically relevant in a concrete way you have to think like the owner of big equipment. Idle equipment is not earning revenue. Busy equipment at least has a chance if it is done efficiently. Telescoping a process so that more steps can be run in the same vessel without solvent changes or excessive purification is always desirable. Moving material between vessels is time consuming and likely labor intensive.

More questions to consider. Does a reaction really require an overnight stir-out. And at reflux? Do you have a method of in-process checks that allow the next step to proceed? What is the minimum solvent grade you can get away with? Can you replace methylene chloride with anything else? What is the minimum purity raw material you can get away with? Unnecessarily high purity specs can be very expensive. Your customer will suffer from this as well.

Learn to get pricing from bulk suppliers. Use those unit prices for your cost calculations. For God’s sake, don’t use the Aldrich catalog for pricing. Remember, you’re trying to make a case for your technology. There should be a costing spreadsheet in your write up.

That’s enough for now. I gotta go home.

 

Public outreach in science is a important element for the maintenance of our present technology-affected (or afflicted) civilization. Science and engineering (Sci & Eng) activity is continually expanding the scope of the known. The global business sector, without relent, puts new technologies to work and retires others as obsolete. It is as though civilization is in a constant state of catch-up with the tools and materials being made newly available. And the quality of news is quite variable.

When it comes to the electronic and print mass media’s government reporting, the emphasis seems to me to focus on the current budgeting process and political conflict therein. These two subjects are in the “eternal now” in the flow of events. The word “news” is just the plural form of “new” so it is natural that news media focus on present budgeting and in-fighting. Media directors and executives know that reporting must be as concrete as possible and what could be more so than large dollar values and pithy news of political hijinks? Both raise our ire because cost and anger are emotional triggers for people. And emotional triggers bring lingering eyeballs to media.

The public not affiliated with Sci & Eng are quite often unaware of what their tax dollars are actually producing, perhaps many years down the timeline. The eventual outcome of government spending on Sci & Eng may be quite specialized and seem only remotely related to non-Sci & Eng life.

It has been my observation that media equates boring content with failure and compelling content with broadcasting success. The word “compelling” is used to describe something that attracts lingering eyeballs. Modern news broadcasting is the process of jumping from one compelling piece to another. I suppose we cannot blame them for this emphasis on superficiality because apparently it is what “we” want. The big We that draws advertisers and thus cash flow to broadcasters. It keeps the lights on and families fed. Basic stuff that can’t be dismissed with a utopian wave of the hand.

If there is going to be any fundamental change in the tenor and quality of content in media, it will have to come from citizen viewers. This leads me to the thrust of this essay: Those knowledgeable in Sci & Eng must bring the value proposition of current efforts in technological civilization to the citizenry, because broadcast media certainly can’t. By “broadcast media” I mean to include everything right down to what appears on your smart phone. Unfortunately, tech content typically emphasizes consumer goods like automobiles, electronic widgets, space, or miraculous medicine.

Those knowledgeable in Sci & Eng must bring the value proposition of current efforts in technological civilization to the citizenry, because broadcast media certainly can’t in any depth. They’re in showbiz. 

Arguments in favor of rational stewardship of our little world won’t influence elected politicians. But informed and persuasive citizens can influence those who are less so and if they apply some leadership. Carefully. Those who may be less educated and less up to date on the sciency subjects do not take kindly to speech that talks down to them. The hand that reaches from above is still above and off-putting. Learn to communicate on even ground.

What works for me in reaching out to all levels of education is to use humor and a bit of showmanship. Reaching out to the public in a way that keeps their attention is hard to do and not everyone is prepared to do it. Lest you think I am describing putting on a show, not entirely. I am saying that by the deft use of knowledge, public speaking skill, and the strength of personality, it is possible to persuade even the scientifically reluctant to perk up and follow your efforts at making a point. But the point must be accessible. Deep detail and meandering monologue will lose your group. Keep your outreach succinct and limit the breadth to a few pearls of wisdom. Get feedback on your presentation.  With any luck, they’ll go home and jump on Google for more.

If you need help with public speaking, join Toastmasters to improve. Try acting lessons. Join a theatre group. Learn to relax, pace yourself, and enjoy speaking. The better you get at the mechanics of public speaking, the more effective you’ll become.

[Note: The crummy WordPress text editor used to write this post is just abysmal. Why it was changed to the current revision is a mystery to me.  -Th’ Gaussling]

As I look back on the chemistry coursework I took as an undergrad, a few classes stand out as especially useful over my career. First some qualifications: I became an organic chemist because I found it to be a good “fit” for my brain. So, organically oriented courses were obviously useful. The chemistry department at my alma mater followed guidelines for the ACS Certified curriculum. Thus required coursework was prescribed and completed.

Chemistry coursework of enduring value.

Sophomore Organic Chemistry:  Fortuitously, I took 2/3 of my general chemistry in the preceding summer, so I was able to take organic chemistry in my freshman fall term. This was the great awakening. It was crystal clear that this was what I was meant to do. The benefits from a course on organic chemistry are many. Foremost on the list is that it is structurally and mechanistically oriented. The cognitive benefit is that a structural and mechanistic approach can render the subject a bit less abstract. At least to highly visual people like myself.

Molecules are tiny objects with even tinier places on them where certain things can happen. Reaction chemistry is revealed as a graphic sequence of specific events on specific objects. This allows the mind to put together patterns of functional groups and reaction motifs. In my view, a year of organic chemistry is the reward for slogging through a year of general chemistry. Gen Chem doesn’t make you a chemist. A tech perhaps. But gen chem is to the chemistry curriculum as The Hobbit is to The Lord of the Rings- a necessary prelude. That is what I used to tell students, anyway.

Qualitative Analysis: This was the third quarter of a 3-quarter sequence of freshman chemistry. It was heavily lab oriented with a focus on the separation and identification of inorganic cations and anions. It was substantially descriptive chemistry where clever schemes were used to isolate ionic species.

Analytical Chemistry: This is where you really begin to feel like a chemist. We all learn skills in this class that last. It is measurement science and error analysis. Every chemical scientist should have a solid foundation in wet chemistry.

Instrumental Analysis: This class was taken after Analytical Chemistry and built upon learnings from it. I’d offer that time spent on learning how your detectors work and their limitations is invaluable.

Organic Qualitative Analysis: I’ve come to learn that this class was an unusual experience. We learned to identify organic substances using fundamental means for 1982. Melting points, melting points of derivatives, NMR (60 MHz!!) & IR spectra, solubility, sodium fusion, Lucas Test, 2,4-DNP-hydrazones etc. We were required to get three data points per unknown to conclude that we had identified the substance. An indispensable resource was a compendium of derivative properties. A challenging but good experience.

Undergraduate Research: Two years of this experience was invaluable as a prelude to grad school. The asymmetric reduction of ketones (1982-84) work here lead to my doing a doctorate in asymmetric C-C bond forming chemistry and a postdoc in catalyzed C-H insertion chemistry. This activity is a must for those who want to pursue post-graduate work.

Advanced Organic Chemistry: What can I say?

Advanced Inorganic Lab: Good experience. Did some glass blowing. Worked on a vac line, tube furnace, and in a glove box. Good intro to airless work which would be important in grad school.

Chemistry coursework that was inadequate.

Inorganic Chemistry: I took this class in a time when symmetry and spectroscopy topics were an emphasis in the textbooks. Maybe it is still like that. But I wish we could’ve spent more time on descriptive and preparative inorganic chemistry.

Physical Chemistry: At the time it seemed as though the mathematical manipulations were more important than what the relationships actually meant. Statistical mechanics was played down in favor of more time on quantum mechanics. On entrance to grad school of the 5 qualifier exams taken, stat mech was the only one I failed.

Coursework outside of chemistry that has been of enduring value.

Microbiology: My only college bio class. I swear that this class has saved me from food self-poisoning more than I realize. That is a lifelong benefit, but so was the insight into a fascinating world. The course included an intro to immunology which also has been useful.

Communications: I made great strides in learning how to do public speaking.

Russian Language:  Took only 1 year- just enough to be dangerous. It was of nearly zero help when I eventually visited Russia years later on a business trip.  I was interested in the history and politics of Soviet Russia in that slice of time during the cold war.

Computer Programming: Should have taken more classes. In the early eighties we had to use either punch cards or the DEC terminal. Oh, I hear that FORTRAN still sucks.

Air Force ROTC: The biggest benefit was that I learned I am not military material in any sense. But, the communication skills and the history of air power were useful. I couldn’t march to save my life. I was Gomer Pyle.

 

 

One of my work duties is to give safety training on the principles of electrostatic safety: ESD training we call it. The group of people who go through my training are new employees. These folks come from all walks of life with education ranging from high school/GED to BS chemists & engineers to PhD chemists & engineers. In order to be compliant with OSHA and with what we understand to be best practices, we give personnel who will be working with chemicals extensive training in all of the customary environmental, health and safety areas.

I have instructed perhaps 80 to 100 people in the last 6 years. At the beginning of each session I query the group for their backgrounds and ask if it includes any electricity or electronics study or hobbies. With the exception of two electricians in the group, this survey has turned up a resounding zero positive responses.

Admittedly, there could be some selection bias here. It could be that people with electrical knowledge generally do not end up in the chemical industry. My informal observations support this. But I’m not referring to experts in the electrical field. I refer to people who recall having ever heard of Ohm’s law. One might have guessed that the science requirements for high school graduation may have included rudimentary electrical concepts. One might have further suspected that hobby electronics could have occupied the earlier years of a few attendees. Evidently not. And it does not appear that parents have been very influential in this matter either.

I’m struggling to be circumspect rather than righteous. It is not necessary for any given individual to have learned any particular field of study. It is not even necessary for most people to have studied electricity. But it is important for a core of individuals to have done so. So, where are they? And why aren’t more people curious enough to strike out on their own in the acquisition of electrical knowledge?

Back to electrostatics. In order to have a working grasp of electrostatic principles, the concept of the Coulomb has to be conveyed. Why the Coulomb? Because it is the missing piece that renders electrostatic concepts as mechanistic. It is my contention that a mechanistic grasp of anything can help a person to reason their way through a question. The alternative is rote memorization. The mechanistic approach is what drives learning in the natural sciences.

To be safe but still effective as an employee, a person needs to be able to discriminate what will and what will not generate and hold static charge to at least some degree in a novel circumstance. By that I mean how accumulated or stranded charge can form and what kind of materials can be effectively grounded. If you are working with bulk flammables, your reflexes need to be primed continuously to recognize a faulty ground path in the equipment around you. At the point of operation, somebody’s head has to be on a swivel looking for off-normal conditions.

It is possible to cause people to freeze in fear and over-react to unseen hazards like static electricity. But mindless spooking is a disservice to everyone. To work around flammable materials safely requires that a person understand and respect the operating boundaries of flammable material handling. Those boundaries are grounding and bonding (see NFPA 77), avoiding all ignition sources, good housekeeping, and maintaining an inert atmosphere over the flammable material.

Much of electrostatic safety in practice rests on awareness of the fire triangle and how to avoid constructing it.

Back to electrical education. There are numerous elements of a basic understanding of electricity that will aid in a person’s life, including safely working around flammable materials. One element is the concept of conduction and what kinds of materials conduct electric current. Another is the concept of a circuit and continuity. Voltage and its relationship to current follows from the previous concepts.

I would offer that the ability to operate software or computers is secondary to basic knowledge of how things work.

Connecting these ideas to electrostatics are the Coulomb and the Joule. One volt of potential will add one Joule of energy to one Coulomb of charges. One Ampere of current is one Coulomb of charges passing a point over one second. Finally, one Ohm is that resistance which will allow one Ampere of charge to move by the application of one volt.

For a given substance- dust or vapor- a minimum amount of energy (Joules) must be rapidly released in order to cause an ignition. This is referred to as MIE, Minimum Ignition Energy, and is commonly measured in milliJoules, mJ.

A discussion on sparking leads naturally into the concept of power as the rate of energy transfer in Watts (Joules per second), connecting to both the Joule and Ohm’s Law. Rapid energy transfer is better able to be incendive owing to the finite time needed for energy to disperse. Slow energy transfer may not be incendive simply because the energy needed to initiate and sustain combustion promptly disperses into the surroundings.

A discussion of energy and power is useful for a side discussion on how the electric company charges for energy in units of kilowatt hours (kWh). This is a connection of physics to money.

The overall point is that a rudimentary knowledge of electrical phenomena is of general use, even in the world of chemical manufacturing. I often hear people talk about the importance of “tech” in regard to K-12 education. By that they seem to say that using software is the critical skill.  I would offer that the ability to operate software or computers is secondary to basic knowledge of how things work. Anyone with a well rounded education should be able to learn to use software as they need it.

In the course of my forays into chemical sourcing or searching for data, I have begun to notice something about product entries in the online Sigma-Aldrich catalog. I’m finding that since the acquisition of Sigma Aldrich by Merck KGaA, MilliporeSigma as it is now known, many of the compounds that I find listed say the product has been discontinued. Is it just fortuitous, or is it not? Is the catalog collection being trimmed?

Have I been collecting data? Pffft! Of course not, silly. It’s just the subjective experience of having found few if any Aldrich catalog entries labeled as discontinued over the past few decades. Recently I’m landing on the pages of discontinued products. Hmmm.

Over the many years, buying reagents from Aldrich has saved countless chemist-days in lab productivity. In fact, the availability of their huge collection of chemicals has driven the direction of much research out there based simply on the availability of reagents for purchase.

I blame the MBA’s. This has the smell of overly smart weasels marketing people.

I’ve been using a Mettler-Toledo (MT) RC1e reaction calorimeter for about 6 years. Our system came with MT’s iControl software, RTCal, and 2 feed pumps with balances. Overall it has proven its worth for chemical process safety and has helped us understand and adjust the thermal profile of diverse reactions. Like everything else, MT’s RC1e has many strengths and a few weaknesses.

The RC1e’s mechanical side seems reasonably robust. Our instrument sits in a walk-in fume hood resting on a low lab benchtop supported by an excess of cinder blocks- it is a heavy beast. During installation we discovered that the unit would not achieve stable calibration with the hood sash down. The control box mounted on the instrument didn’t work properly on installation. After a trip to the repair shop, the box was returned as functional but without finding the fault.

Recently we had a mixing valve fail in the heat transfer plumbing, resulting in down time. Diagnosis of this was unsuccessful over the email and phone, necessitating a service call. Parts may not be inventoried in the US and consequently must come from Switzerland. Expect Swiss prices and less than snappy delivery. Hey, it’s been my experience.

A chiller unit is required for RC1 operation and can add 15-30k$ to the setup cost. Users will have to contend with the loss of floor/hood space in the lab for the chiller and RC1. Chillers can take many hours to get down to the set temperature. Given that RC1 experiments can also be lengthy, plan accordingly. Our (brand new Neslab 80) chiller requires nearly 2 and 1/2 hours to get from +20 C to -20 C, which is the upper chiller temperature we use, depending on the reaction chemistry. For reactions that are on the sporty side, we’ll drop the chiller to – 50 C.  This is near the  minimum temperature for the water-based chilling fluid we use. Early on I opted for an aqueous lithium formate solution with a very low freezing point. It’s a little spendy, but a pool of it on the floor cannot warm up to become combustible and an ESD ignition hazard. Also, it is odorless.

The chiller required the wiring-in of a dedicated single-phase 240 VAC circuit. With the chiller using single-phase and the RC1e using 3-phase 240 VAC, it is important to assure that one cannot inadvertently connect into the wrong power circuit (idiot proofing). The chiller plug design should already prevent this. It is critical that the electrician is alert to this and does NOT jury-rig the plugs to use the same style of connectors because he has only one style in the parts bin.

Some comments on the collection and interpretation of RC1 thermograms.

  • It is critical that those who request RC1 experiments understand the limitations of the instrument. For instance, we use a 2 Liter reaction vessel with a 400 mL minimum fill volume. Refluxing is not allowed owing to the huge thermal noise input from the reflux return stream. Special equipment is said to be available for reflux.
  • Experiments must be carefully designed to elicit results that can answer questions about feed rates and energy accumulation.
  • Like many instruments, the RC1 needs a dedicated keeper and contact person for inside and outside communication. A maintenance logbook should be kept next to the instrument if for no other reason than to pass along learnings from previous issues.
  • If thermokinetic measurement is part of your organization’s development SOP, someone on staff should be reasonably familiar with chemical thermodynamics. That can be a chemical engineer, as may often be the case.
  • The users of thermal data are likely to need help with interpretation of the results. Be prepared to offer advice on interpreting the data, taking care not to over-interpret. If you don’t know, say so. It is easier to claw back “I don’t know” than “yeah, go ahead and do that …”.
  • Do not be anxious to singlehandedly bear the weight of responsibility for safety. Safety is a group responsibility.
  • Be curious. How do the insights and learnings from the data translate into best practices? What changes, if any, can the process chemists make to nudge the process for better safety and yields? A credible specialist in RC can make comments or ask questions that lead to better discussions on thermal hazards. Be a fly in the ointment.
  • Never forget that a reaction calorimeter is a blunt instrument for the understanding of a reaction. An RC1 thermogram is a composite of overlapping solution-phase phenomena. Interpretation of results can be greatly refined by pulling timely aliquots for NMR, GC/MS, or HPLC analysis.
  • A database should be constructed to collect and immortalize learnings from all safety work and RC1 learnings fall into that group.

There is the question of who collects and presents the data. An engineer or a chemist? Engineering thermodynamics is a big part of a chemical engineer’s education and skill set. As a plus, an engineer can take thermal data and apply it to scale-up design for safety and sizing of equipment and utilities. You know, the engineering part.

Do not be anxious to singlehandedly bear the weight of responsibility for safety. Alpha males- are you listening??  Safety is a group responsibility that should originate from a healthy group dynamic.

There’s a good argument for a chemist to conduct RC experiments as well. A trained synthesis chemist is qualified to conduct chemical reactions within their organization. That includes sourcing raw materials, handling them, running the reaction, and safely cleaning up the equipment afterwards. But interpreting RC1 data has a large physical chemistry component. In my experience, run of the mill inorganic/organic synthesis people may have seen PChem as an obstacle rather than a focus in their college education. Their skill set is in instrumental analysis like NMR and chromatography, mechanisms, and reaction chemistry. I would recommend having a PhD chemist with a focus on thermo in a leadership role when calorimetry is a key part of a busy process safety environment.

Safety data can be collected and archived all day long. The crucial and often tricky part is how to develop best practices from the data. I would offer that this is inherently a cross-disciplinary problem. Calorimetric data from reaction chemistry can be collected readily, especially with the diverse and excellent instrumentation available today. Adiabatic temperature rise, ΔTad, can be determined by a chemist, but it’s the engineers who understand how the equipment may respond to a given heat release. A smooth and efficient technology transfer from lab to plant happens when good communication skills are used. Yes, SOP’s must be in place for consistency and safety. But the positive effect of individuals who have good social skills and are prone to volunteering information cannot be underestimated.

 

An automated Windows update disrupted my life today. It swooped in overnight like a winged wraith, did its dark deeds, and flapped quietly back to the dank hole from whence it came. My RC1 data may yet reside unscrambled on the disk drive, but it lies orphaned from the mother iControl application which mockingly professes no recollection of 18 hours of sweet data lovingly produced. The curs in IT can only “tsk, tsk” in their antiseptic way while bobbing pointed heads in faux dismay. Another first-world difficulty uncovered for all to see.

12/20/17. It has been perhaps 6 weeks since CAS has fixed the snag with downloading ACS publications directly from SciFinder. This was a problem because, prior to the SNAFU, the ACS downloads directly from within the SciFinder account would be billed in our monthly statement. Without this feature, every download from the ACS Publications siute, outside the SciFinder account, would then be a separate line item on our in-house expense report with the required circulation for signatures, and absent the contractual discount. So, without the download/billing feature, it was a bigger paper storm and higher document pricing.

Whatever the problem at CAS was, it took some time to fix. Hopefully careers are back on track and all is well.

10/20/17. We have upgraded to Chemical Abstracts Service’s new SciFinder-n which includes PatentPak. After 2 weeks of fairly heavy use I find myself not completely convinced of the marginal value of this upgraded version. Some comments that come to mind-

  • The upgrade resulted in loss of the ability to download ACS publications directly from CAS. This is a glitch that the good folks at CAS are said to be working on. I have no idea as to the extent of this problem across the user base. Obviously ACS publication documents are downloadable from the publication website. The other possibility comes from the official document service of the ACS, FIZ Autodoc. FIZ can provide ACS documents, but for a sizeable premium above an ACS document download fee straight from CAS.
  • All upgrades, good or not good, require the user to adapt to new features. For some navigation, SciFinder-n seems to require fewer clicks and windows to begin a search. The application opens with a Google-like query box allowing the user to input a CASRN, text string, author names, etc., without clicking to a specific search entry window.
  • I use every visit by our CAS rep to lay out what I perceive as weaknesses of SciFinder. So far, no sign that my input even made it into the rental car as they sped away. One big annoyance has been the absence of Boolean searching.  If it can do Boolean searching, I have not found the right syntax or link to use it. This would be welcome.  If I’m wrong here, please leave a comment.
  • I’ve noticed that when looking at a list of references related to a substance query the ‘hits’ are no longer given listing numbers. When you find an abstract to look at more closely and then click back to the list of abstracts, you do not return to the part of the page you clicked away from. I can live with that, but since the document abstracts (see below) are not in a numbered list (1, 2, 3, … n)  you must scroll back and find where you left off by recognition of the text. So unnecessary.

10/24/17. I spoke with a customer service rep at Chemical Abstracts Service (CAS) today. It seems that CAS is in the throes of a software fiasco. The feature that allows a CAS customer to download a pdf document from an ACS publication is presently offline system-wide. This feature allows an account holder to download a document and have the charge added to the monthly billing statement. This greatly simplifies the transaction.

The rep, who was very apologetic, said that as of today it looked like the problem would be fixed in 2 weeks for those using SciFinder Web. No such luck for SciFinder-n however. Evidently the “n” version was released before the ACS document download package was available for it (!!). Luckily a SciFinder-n user can open up the web version. Funny thing is, I have no recollection that our regional representative divulged any of such details during his sales call. Simple sod that I am, my understanding was that “n” was an upgrade encompassing all of the previous web version features. Not quite, it appears. The rep said that the ACS download feature on “n” wouldn’t be available until next year.

Using both the web and the “n” versions side-by-side I must confess that I prefer the web version in many ways. Perhaps due to familiarity. I wonder what others think.

 

 

Enroute to other things I ran across an old Gulf R&D patent, US 3294685, titled “Organic compositions containing a metallo cyclopentadienyl”. Sifting through the description my eye caught the interesting content below:

July 1941. A test spray was prepared by dissolving 2.5 grams (3.2 percent) of iron dicyclopentadienyl in ml. of a typical household insecticide base oil. The tests made with this solution employed a dosage of IO-second discharge. An equilibrium :period of 15 seconds followed by an exposure period of 70 seconds, during which the mist was permitted to settle on adult house flies confined in a screen-covered dish, was employed in the tests. The results of the tests showed that of the flies which had been contacted with the base oil containing 3.2 percent by weight of iron dicyclopentadienyl, 53.6 percent were dead after 24 hours. Of theflies which were contacted with the base oil alone, only 13.0 percent were dead after 24 hours. Check flies which were confined for 24 hours without having been contacted with either the base oil or the base oil containing iron dicyclopentadienyl had a death rate of only 0.4 percent. The better than fifty percent mortality of the flies treated with the base oil containing iron dicyclopentadienyl is indicative of the insecticidal properties of naphthas containing a small amount of iron dicyclopentadienyl. Naturally, the amount of metallo cyclopentadienyl used in insecticidal compositions-will vary with the particular compound employed and also depends upon the particular insects for which the spray is intended. The amount of iron dicyclopentadienyl employed in insecticidal compositions intended for use on flies is between about 1.0 and 10.0 percent by weight.

Ya know, a greater than 50 % kill rate seems to be getting a bit sporty for the flies. The ol’ boys at Gulf were studying the suitability of a variety of ferrocene analogs for fuel additive application. What lead them to go from octane enhancement and smoke control to killing flies is not revealed in the patent.

Notice the nomenclature in the patent language. The word ferrocene is not mentioned. Looking at the timeline we see that the Gulf ‘685 patent was filed April 21, 1952, not long after the publication of this curious iron cyclopentadienyl compound by two groups, Kealy & Pauson on 12/15/51, and Miller, Tebboth, and Tremaine on 1/1/52. Though Pauson and Keely published first, an examination of the papers show that Miller, Tebboth, and Tremaine were first to submit- July 11, 1951 vs August 4, 1951 for Pauson and Kealy.

The day before Gulf filed the patent application, April 20, 1952, a groundbreaking paper by Wilkinson, Rosenblum, Whiting, and Woodward was published on the proposed structure of iron bis-cyclopentadienyl. It is reported that the name ferrocene was invented by Mark Whiting, a student of R.B. Woodward and coauthor of the 1952 paper in JACS. The name derives from the ferrous ion and the aromatic (“benzene”) nature of the cyclopentadienyl ligands.

The curious structure was proposed largely on the strength of a single C-H IR band at 3.25 μ. Since all of the C-H bonds appeared to be equivalent, the only structure compatible with the formula, charges and symmetry was the famous η5 (eta five) sandwich structure. Later the word metallocene finds use for this class of substances.

There is disagreement as to some of the details outlined above. An excellent article by Pierre Lazlo and Roald Hoffmann navigates some of the narrower channels in the history of ferrocene. It is well worth the read. Lazlo & Hoffmann suggest that Woodward is thought to have conceived the sandwich structure.

Ferrocene and derivatives would soon prove useful in many areas. A more obscure application is found in the field of rocket propellant additives and function as burn rate stabilizers. In fact, certain ferrocene derivatives appear on the US Munitions List, 22 CFR 121.1, Category V, (f)(4) Ferrocene Derivatives. A good overview of ferrocene and other metallocenes can be found in Wikipedia.

Circling back to the beginning of this piece, the patent application for Gulf ‘685 was filed 4/21/52, only 4 months after the publication on 12/15/51 of the Pauson & Kealy paper and two weeks later the Miller, et al., paper on 1/1/52. In the 4 months between Pauson & Kealy and the Gulf patent filing, two independent groups had published papers reporting the preparation of iron dicyclopentadienyl by different methods, a Harvard group had postulated a structure for the compound using IR data and a novel bonding type, and the Gulf R&D group had produced various analogues for testing as fuel additives. In this short time interval, the first organo-iron compound was taken from a literature source through industrial R&D and a patent application. As a premium, Gulf even determined that it had insecticidal properties. Much happened in a short time.

 


Wilkinson, Rosenblum, Whiting, and Woodward J. Am. Chem. Soc., 1952, 74 (8), pp 2125–2126. DOI: 10.1021/ja01128a527

Kealy and Pauson, Nature, 168, 1039 (1951). Received Aug. 7, 1951.  DOI: 10.1038/1681039b0

Miller, Tebboth, and Tremaine J. Chem. Soc., 1952,0, 632-635. Received July 11, 1951. DOI: 10.1039/JR9520000632

Laszlo P., Hoffmann R. ACIEE, 2000 Jan; 39(1):123-124.  DOI: 10.1002/(SICI)1521-3773(20000103)39:1<123::AID-ANIE123>3.0.CO;2-Z

One of my job responsibilities is to educate new hires on reactive hazards and the basics of electrostatic discharge safety in the chemical manufacturing environment. The attendees are usually new plant operators with the occasional analytical chemist also in attendance. The educational background for the operators is nearly always a high school diploma with work experience of widely varying duration in non-chemical industries. Since we are far from the regional chemical manufacturing centers in the USA, we rarely encounter applicants from our industrial sector. Commonly the analysts arrive with a BA/BS in chemistry, biochemistry, or even biology sometime in the past.

In their 1 to 2 weeks of introductory training I’m given 1 hour for each of the 2 topics- barely enough time to wedge in important vocabulary let alone develop a command of, well, anything. My approach is to first talk about the difference between hazard and danger with some folksy examples. Then I introduce the general concept of stability using examples boxes on a rising incline. From there, we talk about stability as related to variously truncated inverted conical objects. The notion of instability, meta-stability, and stability are teased out of examples of the tipsiness of inverted cones leading to a change of state under the influence of external forces. This is very concrete and primes the mind to begin to grapple with the abstract notion of substances undergoing change depending on the precariousness of their initial state or the intensity of external influence.

Synthetic chemistry is very much about the careful manipulation of instability in order to produce the sort of change that is desired. Highly stable materials, i.e. sand, are not desirable in a chemical synthesis minimally because they are resistant to alteration. Many reaction steps may be performed and much cost incurred in order to produce features (functional groups) that are sufficiently unstable to undergo the series of desired connections.

After all of the above, the remainder of the hour is spent talking about chemical hazards and how some of them may be passivated by paying attention to the fire triangle. Also the matter of chemical compatibility is introduced as well as the existence of various categories of substances with examples. Of course, this means nothing to them. It’s just a bunch of new words arranged in unfamiliar ways. I’m quite well aware of this, but the purpose is to prime the pump so that when they hear these solvent names and words like acidic, caustic, basic, pH, quench, etc., then can begin the long process of connecting the dots to produce a better picture of their workspace.

The topic of ESD – electrostatic discharge – has its own peculiar challenges. First of all, static charge is invisible, pervasive, and unless you have direct measurements, provides hazards of an unknown risk. To understand ESD hazards, the learner should be exposed to the units describing static charge. These include the Coulomb (C), the volt (Joules/C), the Joule (J), area charge density (µC/m^2), power (Watts = J/sec), the Ohm (Ω = V/A) and the Siemens (S = 1/Ω), and the Ampere (A = C/sec).

Herein lies the real point of this essay. In teaching ESD safety for 4-5 years, I have met perhaps 2 attendees (engineers) out of many dozens who recall having taken coursework relating to basic electricity. I always begin the seminar by taking a poll on who has heard of Ohm’s Law. In reality, I don’t expect electrical proficiency from folks who have not worked in an electrical field. What surprises me is that so few can recall having heard of Ohm’s Law. How is it that we are letting so many people graduate from high school without some course work introducing the very basics of electricity?? This related to one of the most pervasive and influential technologies in our time. I think this is a stunning oversight.

“A’hem, cough cough,” you sputter, “but surely …” –short pause for effect- “… students who have taken high school physics have had instruction in electricity,” you reply with obvious incredulity.

If you had said this you’d be correct. But the educational profile of many factory workers doesn’t seem to include many people who have, in our experience, taken physics in high school. Those from the electrical trades tend not to show up from the temp agency for screening.

So let me end this by asking the mandarins of our school districts why we let students not college bound  graduate without some background in the basics of electricity or electronics? To repeat, this is a stunning oversight, given the extensive use of electrical functions and objects in our lives.

 

 

Archives

Blog Stats

  • 523,029 hits