"What's Your Excuse"

The Industrial
Catalysis Experts

Win a FREE PTC coffee mug!!!

Got a good excuse for not trying/using PTC?
Complete your contest entry below.

Recent Winners

As we all know, chemists, engineers (and sometimes even managers) can be very creative. This creativity not only applies to technical innovation, it can also be applied to coming up with excuses to rationalize avoiding important issues. In the past few years, I have heard some incredibly creative excuses for not trying PTC. In some cases, the excuses were overcome and over $1 million were subsequently saved by converting to the PTC process. In many of these cases, the excuses (and politics) prevailed and PTC was not even tried. In one case, after the non-PTC process was already commercialized, it was shown that the PTC process was superior, but for non-technical reasons, the PTC retrofit was not implemented.

Although I'm sure that YOUR company would never pass up profit opportunities due to politics, stubborness or weak excuses, you or one of your co-workers may still be creative enough to come up with an amusing excuse for not trying PTC when you are trying to improve an existing manufacturing process or developing a new process for the manufacture of an organic chemical.

Please send your excuse for not trying/using PTC by filling out the form below. We will choose the best excuse of the month, publish it on this page and send the winner a PTC coffee mug.

Please indicate if you want your name and company affiliation to be shown with your contribution (we will not publish this information unless you authorize it).

To give you an idea of the kind of real excuses we have heard click here


Got a good excuse for not trying/using PTC?
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My Excuse Contest Entry is:

Excuses we have already heard:

Excuse #1: "I once tried A phase-transfer catalyst and THEY don't work!!!"
(from a process chemist suffering from project overload; by the way, the catalyst was benzyl triethyl ammonium chloride)

for answer to Excuse #1 click here

Excuse #2: "We already get a 95% yield in the plant...we don't need PTC or anything else!" (from a plant manager)

for answer to Excuse #2 click here

Excuse #3: "We will probably have to invest a lot of engineering time, capital or both to get intimate mixing of the two phases!" (from a development engineer)

for answer to Excuse #3 click here

Excuse #4: "We are in the cost cutting mode right now and we just can't afford to look at PTC right now!!!" (from an R&D Director - who, by the way, is no longer employed by this multi-billion dollar company)

for answer to Excuse #4 click here

Excuse #5: "The catalyst is too expensive" (I actually said this to my boss in 1984 and since I have heard this from a process chemist and from a purchasing manager)

for answer to Excuse #5 click here

Excuse #6: "The catalyst decomposes before the reaction is over" (from a process chemist)

for answer to Excuse #6 click here

Excuse #7: "By the time I find the most economical catalyst for reactivity, figure out how to separate the catalyst from the product and choose a suitable solvent, I may not make my project deadline" (from a process chemist)

for answer to Excuse #7 click here


Answers to excuses:

Answer to Excuse #1: The catalyst chosen in that case, benzyl triethyl ammonium chloride, is not very effective for "intrinsic reaction rate limited reactions" and a catalyst such as Aliquat 336 (trademark of Henkel Corporation) or even tetrabutyl ammonium bromide would have been a much better choice. There are hundreds of succesful PTC/hydroxide reactions which use benzyl triethyl ammonium chloride, but other PTC reactions (such as the famous Herriott, A.; Picker, D. J. Amer. Chem. Soc., 1975, 97, 2345) give non-detectable reactivity with this catalyst and outstanding reactivity with Aliquat 336.

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Answer to Excuse #2: I asked the plant manager if he would like to reduce cycle time in the plant and he responded enthusiastically and then added a request to eliminate the dipolar aprotic solvent from the process. Phase-Transfer Catalysis has been used in several commercial plant retrofits in which the pre-retrofit yield of >90% was not changed, but cycle time reductions results in very large savings (mostly due to shortened reaction times, elimination of workp unit operations, reductions in solvent usage and/or solvent replacement).

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Answer to Excuse #3: Most commercial PTC reactions don't need elaborate agitation schemes, since they are usually "intrinsic reaction rate limited." This means that the rate limiting step is the actual chemical reaction, not the transfer of one of the reactants to the reaction phase or an interfacial reaction. Only when the reaction is "transfer rate limited" or "interfacial" will stirring make a difference. When a reaction is "intrinsic reaction rate limited" the reaction rate will not increase by one iota with increase in agitation efficiency. I understand that it is instinctive for engineer to want to achieve intimate mixing when they see two phases. Let's face it...in the absence of a phase-transfer mechanism, you usually do need great mixing to get reactants located in separate phases to react!

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Answer to Excuse #4: This is one of my favorites! My response was "If you are really trying to cut costs, the strength of PTC is in reducing the cost of manufacture, so you CAN'T afford to not to look at PTC right now!" (please forgive the grammatically incorrect double negative in the sentence).

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Answer to Excuse #5: This is a common mistake, especially when someone utters the words "crown ether." The answer is that you need to calculate the cost of the catalyst per kg of PRODUCT not per kg of catalyst! If you can use 1 mole% of a phase-transfer and achieve a 40% reduction in process cycle time, you can do the math to figure out if a more expensive catalyst is worth the ultimate benefit. By the way, I once heard this excuse from a purchasing manager who was using the ultra cheap but not very effective benzyl trimethyl ammonium chloride to make a specialty chemical with a relatively high profit margin, and he didn't want to consider the more expensive and more effective larger quats (which are not considered very expensive).

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Answer to Excuse #6: The chemist was not aware of thermally stable phase-transfer catalysts.

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Answer to Excuse #7: Get an industrial PTC Technology expert to help during the screening stage of the project. The chemist is right...there are a lot of considerations which need to be addressed when developing a new PTC process or retrofitting an existing plant with PTC. It is not time-effective for every chemist to read the 8000 PTC articles, 1500 PTC patents and every word of the classic PTC books. PTC Technology experts (who wrote the book) can help you reduce the development cycle time for your PTC process and increase profit. Don't pass by great opportunties for increasing your profit and process performance because you are embarrassed to bring in a dedicated industrial PTC expert. Chemists, engineers and managers who bring in industrial PTC Technology experts are considered heros within their organization when they achieve very high performance and are credited with efficient use of development resources.

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Name: name withheld
Excuse: "Our budget for bringing in new technology this year has been used up. However, our chemists are quite interested in PTC so please call back at the beginning of the year."

Name: name withheld
Excuse: "Use of a phase transfer catalyst is counterintuitive when the reactant is water sensitive."
Response: Very often the organic phase in a PTC system "protects" water-sensitive organic reactants (such as phosgene, benzoyl chloride and dimethyl sulfate) from the aqueous phase. Interfacial hydrolysis is usually difficult under the mild conditions which the desired PTC organic reaction is favored.

Name: name withheld
Excuse: "If I switch catalysts now, I'll NEVER finish my dissertation!"

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What's your excuse?!?!?!?!?!?!?!?!?!?

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last updated 20-Jan-2000