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After following a chat room discussion on process safety, I find myself mixed on the matter of what is called green chemistry. In the present example, a fellow wanted to methylate a phenol but didn’t want to use dimethylsulfate or some similar methylating agent. He wanted something that was “green”.

Suggestions were varied, including a recommendation on the use of dimethyl carbonate as methylating agent and a few other approaches through aromatic substitution. One contributor wisely reminded contributors about going into the weeds with low atom efficiency.

Green chemistry is the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances. Green chemistry applies across the life cycle of a chemical product, including its design, manufacture, use, and ultimate disposal. Green chemistry is also known as sustainable chemistry.”  -EPA

When green organic chemistry is the goal in synthesis, it pays to be sure that there is an accepted definition of green chemistry on site.  The merits and definitions are explained elsewhere. Difficult questions come up when a non-green substance is replaced with something that may be “more green” but needs 2 steps instead of 1. Or when green but more expensive reagents and solvents are needed. What is best? In this case, greater safety, lower cost, higher space yields, reduced waste generation, and fastest reaction times will be the real drivers. The business to business market will not pay more for a green product while a cheaper non-green alternative is present. If you want to get an existing customer to requalify an existing product from a new green process, be prepared to discount the price in exchange for the customer having to go through a requalification process. Customers do not like change at all.

Under what conditions would management allow a process choice that is greenish but obviously more costly? Possibly never. A greener process needs to give a cost savings somewhere. Barring draconian regulation, a successful green process will have a cost benefit. The benefit may be in lower direct cost of manufacture, satisfaction of a process requirement by a customer, or a hedge against future regulatory restrictions.

Solvents may be one of the easier opportunities for green chemistry. For a given process, there may be a bit of latitude with the solvent. Sometimes the issue of solvent residues in the product may arise. Some solvents are easier to strip away than others. No one will choose a green solvent that is hard to remove from the product. Again, the drivers will be those mentioned above.

Another green opportunity is when we automatically choose a stoichiometric reducing agent when we could have looked at a catalytic system with hydrogen. Catalyst costs per kilogram of product can range from negligible to high. One advantage of using expensive platinum group metal catalysts is that the metal is usually recyclable, which is greenish. However, any organic ligand present does get incinerated producing non-green emissions in the process of energy intensive metal refining. If catalytic hydrogenation requires the installation of new capital equipment, then the installation costs in time and money may prevent a switch.

For green oxidation, oxygen in the air is cheap and abundant but carries a big problem. Using an oxidizing gas in the presence of a flammable liquid reaction mass can give rise to an explosive atmosphere in the headspace of the reactor. This is a non-starter in industry. Catalytic oxidation using a greenish primary oxidant in solution is a good place to start. I’ve heard of hydrogen peroxide or peroxyacetic acid referred to as greenish.

The big problem with green synthetic organic chemistry is that in order to synthesize a molecule, the structural precursors must be sufficiently green, reactive and selective to run on a reasonable timescale and at acceptable cost. And they must not produce non-green side products or wastes that spoil the advantage of the target green step. A weighing of the pros and cons of any attempt to do green chemistry will always be needed and subjective decisions will be made on what constitutes green.

While we are all struggling to be greener, let’s not forget to remind ourselves and others that reduced consumption of almost everything is a green step we can all take right now.

It’s difficult to describe how badly the New Chemicals division in the Office of Pollution Prevention and Toxics (OPPT) at EPA is performing these days, but let me try. The commercialization of new chemicals (not on the TSCA Inventory) not otherwise regulated requires that new chemical substances (NCS) be reviewed and granted following a Pre-Manufacture Notice (PMN) or a Low Volume Exemption (LVE) submission under the Toxic Substances Control Act (TSCA), should they meet internal criteria regarding safety. Exposures and doses to workers or the environment may be measured by the applicant or modeled using EPA in-house software. R&D only chemicals are exempt from such evaluation no matter the scale.

The application process requires the disclosure of the NCS composition and structure, the manufacturing and/or use operation in considerable detail, physicochemical properties and, if available, a wide range of worker and environmental hazards. Imported chemicals not on the TSCA inventory also require TSCA approval just as though they were being manufactured in the USA. Food, drugs and pesticides are not controlled under TSCA. Under penalty of law, all submissions must have the best and most accurate available information, particularly with regard to hazard information. No fibbing allowed.

The issues I’m about to recount started sometime in early 2021. Some speculate that a particular interpretation of the law promulgated by TSCA was adopted. I can’t provide references, however.

By statute, an LVE filing for instance, must be examined and be given a grant, conditional grant, or denial within 30 days. It is currently taking much longer than that: 60 to 100 days or longer. I have some that are still pending after 7 months. PMN filings take longer to process, about 9-12 months. or worse.

Aren’t these delays just a petty annoyance? Well, no. Part of a new product development timeline is getting regulatory approval. If this approval is subject to large delays with uncertain outcomes, then the launch date can become very fuzzy. The consequence for the end user is that scheduling their production activity becomes impossibly vague. Denials of LVE and PMN filings are not uncommon. Don’t expect a lot of sympathy from customers about EPA problems.

The last thing you want is some plebe right out of school with no professional experience in commerce to be handing out the regulatory death penalty to your expensive new technology. Handling hazardous materials safely and without environmental harm is done all day every day all over the world. There is a saying in the chemical industry: If you think safety is expensive try having an accident. There is considerable financial incentive to running a chemical plant safely and within regulations.

There seems to be a troubling issue involving the assumptions that EPA makes in regard to handling the NCS. The feedback I receive suggests that the engineers and toxicologists are ruling based on the worst case exposures that they imagine are going to happen. They imagine that workers and the environment will be exposed to the NCS as if workers aren’t wearing personal protection equipment (PPE) or there was no barrier to the environment. You can plainly state that these exposures won’t happen and state why, but they want evidence evidence that they cannot define that something will not happen. In other words, they want proof of a negative.

Another problem with EPA seems to be the sophomoric view that chemical hazards can always be abated by using safer chemicals. There may be a speck of truth to this generalization. In the formulations industry, for example. Replacing hazardous ingredients in mascara or shampoo with those that are less hazardous may be quite uncomplicated. Reducing chemical hazards is part of ethical business operations and is expected with ISO 9001 registration. The catch for chemical manufacturing is that the chemical features that make chemicals reactive and hazardous are usually the same features that make them essential to synthesis. Except for solvents and filter aid, unreactive chemicals are not very useful in synthesis. Synthetic chemistry is about manipulating the reactive features of one molecule with another to yield a useful product.

The delay issue is not unknown to EPA. In fact they are painfully aware of it all the way up to the EPA administrator. The good folks at EPA are doing their best with absurdly limited resources. We’re told that the TSCA division is 50 % understaffed, and many of the staff they do have are inexperienced. They have a computer system that is obsolete by many generations. You can see this by filing on their website. They have taken to denying submissions that are flawed in a minor way rather than continuing to work with the applicant to fix the problem. This excess fastidiousness ratchets down their backlog, at least in the short term.

The problems at EPA stem from the inability of congress to buckle down and provide proper funding. Only congress can act to boost staffing or computers. Lobbyists are working on it but, unfortunately, this is not an appealing issue for a congress person to take up and run with. Maybe we can get that cancerous A-hole Tucker Carlson to howl about it on the tube. Then we might see some movement.

Here is a link to one of my better posts. It is titled Flame and Ash. There is some interesting history in the development of illumination. It sounds trivial, trying to get good illumination from a flame, but it took a while.

I’m posting a link to the story of the astoundingly fast discovery and market entry of Pfizer’s Paxlovid, their small molecule contribution to the treatment of COVID-19. You have to wonder if the emergency use authorization came before the patents were allowed.

Chemical process scale-up is a product development activity where a chemical or physical transformation is transferred from the laboratory to another location where larger equipment is used to run the operation at a larger scale. That is, the chemistry advances to bigger pots and pans, commonly of metal construction and with non-scientists running the process. A common sequence of development for a fine chemical batch operation in a suitably equipped organization might go as follows: Lab, kilo lab, pilot plant, production scale. This is an idealized sequence that depends on the product and value.

Scale-up is where an optimized and validated chemical experimental procedure is taken out of the hands of R&D chemists and placed in the care of people who may adapt it to the specialized needs of large scale processing. There the scale-up folks may scale it up unchanged or more likely apply numerous tweaks to increase the space yield (kg product per liter of reaction mass), minimize the process time, minimize side products, and assure that the process will produce product on spec the first time with a maximum profit margin.

The path to full-scale processing depends on management policy as well. A highly risk-averse organization may make many runs at modest scale to assure quality and yield. Other organizations may allow the jump from lab bench to 50, 200, or more gallons, depending on safety and economic risk.

Process scale-up outside of the pharmaceutical industry is not a very standardized activity that is seamlessly transferable from one organization to another. Unit operations like heating, distillation, filtration, etc., are substantially the same everywhere. What differs is administration of this activity and the details of construction. Organizations have unique training programs, SOP’s, work instructions, and configurations of the physical plant. Even dead common equipment like a jacketed reactor will be plumbed into the plant and supplied with unique process controls, safety systems and heating/cooling capacity. A key element of scale-up is adjusting the process conditions to fit the constraints of the production equipment. Another element is to run just a few batches at full scale rather than many smaller scale reactions. Generally it costs only slightly more in manpower to run one large batch than a smaller batch, but will give a smaller cost per kilogram.

Every organization has a unique collection of equipment, utilities, product and process history, permits, market presence, and most critically, people. An organization is limited in a significant way by the abilities and experiences of the staff who can use the process equipment in a safe and profitable manner. Rest assured that every chemist, every R&D group, and every plant manager will have a bag of tricks they will turn to first to tackle a problem. Particular reagents, reaction parameters, solvents, or handling and analytical techniques will find favor for any group of workers. Some are fine examples of professional practice and are usually protected under trade secrecy. Other techniques may reveal themselves to be anecdotal and unfounded in reality. “It’s the way we’ve always done it” is a confounding attitude that may take firm hold of an organization. Be wary of anecdotal information. Define metrics and collect data.

Chemical plants perform particular chemical transformations or handle certain materials as the result of a business decision. A multi-purpose plant will have an equipment list that includes pots and pans of a variety of functions and sizes and be of general utility. The narrower the product list, the narrower the need for diverse equipment. A plant dedicated to just one or a few products will have a bare minimum of the most cost effective equipment for the process.

Scale-up is a challenging and very interesting activity that chemistry students rarely hear about in college. And there is little reason they should. While there is usually room in graduation requirements with the ACS standardized chemistry curriculum, industrial expertise among chemistry faculty is rare. A student’s academic years in chemistry are about the fundamentals of the 5 domains of the chemical sciences: Physical, inorganic, organic, analytical, and biochemistry. A chemistry degree is a credential stating that the holder is broadly educated in the field and is hopefully qualified to hold an entry level position in an organization. A business minor would be a good thing.

The business of running reactions at a larger scale puts the chemist in contact with the engineering profession and with the chemical supply chain universe. Scale-up activity involves the execution of reaction chemistry in larger scale equipment, greater energy inputs/outputs, and the application of engineering expertise. Working with chemical engineers is a fascinating experience. Pay close attention to them.

Who do you call if you want 5 kg or 5 metric tons of a starting material? Companies will have supply chain managers who will search for the chemicals with the specifications you define. Scale-up chemists may be involved in sourcing to some extent. Foremost, raw material specifications must be nailed down. Helpful would be some idea of the sensitivity of a process to impurities in the raw material. You can’t just wave your hand and specify 99.9 % purity. Wouldn’t that be nice. There is such a thing as excess purity and you’ll pay a premium for it. For the best price you have to determine what is the lowest purity that is tolerable. If it is only solvent residue, that may be simpler. But if there are side products or other contaminants you must decide whether or not they will be carried along in your process. Once you pick a supplier, you may be stuck with them for a very long time.

Finally, remember that the most important reaction in all of chemistry is the one where you turn chemicals into money. That is always the imperative.

One of the safety seminars I teach is on the general topic of reactive hazards. There is a bit of a challenge to this because the idea is to cultivate informed caution rather than allow broadband fear to rule. It is challenging because my class is generally populated with non-chemist plant operators or other support staff. Out in the world the word “chemical” is generally taken to be an epithet and indicative of some malign influence. We who work with chemicals are in a position to bear witness to the reality of chemistry in our lives and to speak calmly and reasonably about it, without crass cheerleading.

Here is how I look at this. There are hazards and there are dangers. A hazard is something that can cause harm if it was to be fully expressed by way of physical contact with people or certain objects, unbounded access to an ignition source, exposure to air, etc. A critical feature of the hazard definition is that there are layers of protection preventing undesired contact. Hazards can be contained. A contained hazard is safer to be around than an uncontained hazard.

An uncontained hazard is that which can cause harm without the interference of effective layers of protection. A hungry tiger in a cage is hazardous in that there is the potential for trouble if the cage is breached. Being openly exposed to that tiger is what I’ll call dangerous.

Likewise, a stable chemical in a bottle has a physical layer of protection around it. A policy on the use of that bottled chemical constitutes a concentric administrative layer of protection. The bottle sitting in a proper cabinet within a room with limited access has more layers of protection. The policy of selling that chemical only to qualified buyers is a further layer of protection.

Egg white to which has been added several drops of conc H2SO4 (bottom) and 50 % caustic (top). Two minutes have elapsed. The point of this demo is to show what might happed to a cornea on contact with these reagents. The clouding is irreversible. People remember demonstrations.

It is possible to work around contained hazards safely and most of us do this outside of work without giving it much thought. Hazardous energy is exploited by most of us in the form of moving automobiles, spinning jet turbines, rotating machinery of all kinds, compressed gases and springs, and flammable liquids. Safe operation around these hazards is crucial to the conduct of civilization right down to our daily lives.

It is very easy for experts to frighten the daylights out of people by an unfortunate choice of words or simply dwelling on the hazardous downside too much. Users of technology should always be versed in the good and bad elements as a matter of course.

Risk can be defined as probability times consequence. So, to reduce risk one can reduce probability, diminish undesired consequences, or both.  This is the purpose of LOPA, or Layers of Protection Analysis. LOPA can provide a quantitative basis for safety policy. The video below will explain.

https://youtu.be/L3kQ9DKHS5A

Designing for tolerable risk is something that all of us in industry must come to grips with.

 

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.

 

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 ever having 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.


Addendum 8/16/18.  Since I wrote this essay, I’ve taught another 2 groups of trainees and not a single one of the 12 individuals could say that they had heard of Ohm’s law. All were high school grads over an age range of 22 to ~50. One had fresh BS Chem. E. degree.  Evidently none had enough inclination in their travels to noodle their way through a rudimentary grasp of volts, ohms, amperes and basic electronic components. I find this incredible given the penetration of electrical contrivances in our lives.

This feeds into a pet theory of mine that true expertise is being replaced with software skills. I know this because it seems to be happening to me as well. Is this an aspect of the Dunning-Kruger effect?

Interesting. I know two chemists and an engineer from my miniscule spheroid who have recently joined the marijuana extraction industry here in Colorado. Crimony, it makes me wonder what my problem is. Alright, it turns out that’s easy to explain. I really dig reaction chemistry and thermo, you know, real sciency stuff. Not much of that in the retail or wholesale extractives business. I have this suspicion that it will soon – if not already – be corporatized, IPO’d, and raced full throttle by scheming finance MBA’s like every other growth business. They can have it. Capitalism is like a stomach- it has no brain. All it can do is endlessly demand more.

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.

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