Exploitation and Capitalization of Mutual Behavior of Chemicals (Sociochemicology) and Process Equipment for the Manufacture of Propofol

Sociochemicology ^(1,2,3,4) is an important member of the triumvirate ⁽⁵⁾ necessary for the development of every life style (additives) and life span (pharmaceuticals) improvement chemical. Physical state of chemicals used and produced in the process along with the equipment used play a significant part in process selection and their design. Each has its say and influence in process development. From my perspective these phenomenon are very much recognized but may and/or not fully capitalized on. 

 

Purpose of this note is not to be critical of the lab development and commercialization process/es but allow us to understand and capitalize on how the influence of state of materials used and produced in chemical processes provide us the process simplification opportunities and clues. Unit processes and operations can be and need to be exploited to simplify the process. Chemistry and process of propofol is used as an example. 

  

Commercialization: Batch vs. Continuous Process:

 

We have to accept and acknowledge chemical processes have a definition to be a batch process or a continuous process ^(1,2,3,4). Chemistry processed in any processing equipment that is not specifically designed for the process is generally a batch process. In such processes intermediate products are held over time for further processing. Equipment specifically designed to produce a product and processed without being held for time for the next reaction process step operates 24x7x350 hours per year, is a continuous process. Claiming a lab or plant process where intermediate reaction product is held to be processed for some time is a batch process and calling it a continuous process is mis-representation of reality. 

 

Each product’s raw materials and intermediates along with physical and chemical properties and nuances of process equipment need to be exploited. Any experienced process design chemist and/or chemical engineer, i.e. part the village ^(1,2,3,4,5) once exposed to the chemistry in the lab can create simple processes if they are well versed in exploiting social behavior of chemicals and process equipment. It is emphasized again that laboratory just shows the pathway. Economic processes are build. Imagination, creativity and experience of chemists and chemical engineers are of vital importance ^(1,2,3,4,5). Impact on environmental conservation can be effortless and efficient. 

 

Propofol Manufacture:

 

Table 1 outlines four alternate propofol synthesis routes. These chemistries are similar and involvement of Village ^(1,2,3,4) and triumvirate ⁽⁵⁾ is necessary from the onset. Information can be used to select the most economical process. Ease of availability of the raw materials, their prices and business strategy drive the selected process. One will have to test the selected pathway using knowledge and experience. Based on global volume of propofol active ingredient the synthesis and its formulation can be a continuous process. 

 

Friedel-Crafts reaction generally use aluminum chloride. It is a challenge to handle in the lab and the plant. Significant investment is needed to have a safe process. Production of Propofol ^{(6, 7, 8, 9)} uses Propofol uses concentrated sulfuric acid instead of aluminum chloride in their Freidel Craft reaction. This is much safer route. Each of the referenced process uses solvents. 

 

For each case discussed in Table 1 creative and imaginative chemical engineer and chemist with the help of village ^(1,2,3,4,5) can easily select and design a manufacturing process that can be modulated to meet variable global production demand and even be used to produce other products if equipment modifications are needed.

 

Each cited chemistry in Table 1 is very similar except for some of the reactants. Paths ^(6,9) use hydroxy benzoic acid and 2-ethoxyethanol or ethyl alcohol for the decarboxylation step to produce propofol. Paths ^(7,8) use methylparaben as the starting raw material and use ethylene glycol for the decarboxylation step ⁽⁸⁾. Physical properties can be exploited to simplify the process and create an all liquid process that can be totally controlled using commercially available control technologies. Several other published routes are not discussed. 

 

Pramanik Process (6)
H2SO4 + IPA	NaOH +2-ethoxyethanol
4-hydroxy benzoic acid ----------------> 3,5-diisopropyl-4-hydroxybenzoic acid -------------------------> Propofol
Vinet Process (7):
H2SO4 + IPA	NaOH +2-ethoxyethanol
Methyl paraben ----------->  3,5-di-isopropyl-4-hydroxybenzoic acid ---------------------------------> Propofol
Chodankar (USP 11,767,281 B2) (8)
H2SO4 + IPA	NaOH +2-ethoxyethanol
Methyl paraben ----------->  3,5-di-isopropyl-4-hydroxybenzoic acid ---------------------------------> Propofol
Coeuillas A. et.al (9)
H2SO4 + IPA	NaOH +ethyl alcohol
4-hydroxy benzoic acid ----------------> 3,5-diisopropyl-4-hydroxybenzoic acid -------------------------> Propofol

                                     

                                                            Table 1: Process chemistries of Propofol

 

Table 2 is compilation of properties of the chemicals used in various propofol processes. Economics and ease of manufacturing process indicates that process based on methyl paraben route due to its lower raw material price and reaction temperatures could be the preferred route. Methyl paraben can be used as a melt and reacted with sulfuric acid and isopropyl alcohol to produce 3,5-Diisopropyl-4-hydroxybenzoic acid. By products produced would be water soluble and they can be separated using a differential gravity decanter to produce excellent feed for the distillation step. 

 

Village’s ^(1,2,3,4,5) creativity, process engineering and reaction kinetics would be needed to have an all liquid process. My conjecture is that the higher reaction temperatures will keep the reaction mass as a melt, speed the reaction and minimize solvent use. Each route would have to be tested in the laboratory and piloted to commercialize the most economic process.    

	FORMULA	MOL. WT.	MP °C	BP, °C	CAS NUMBER
4-Hydroxy benzoic acid	C7H6O3	138	214.5		99-96-7
H2SO4	H2SO4	98	10.2	337	7664-93-9
Iso propyl alcohol	C3H8O	60	-89	82.6	67-63-0
3,5-Diisopropyl-4-hydroxybenzoic acid	C13H18O3	222	146	343.5	13423-73-9
Methyl Paraben	C8H8O3	152	131	265	99-76-3
NaOH 50%	NaOH	40	12	140	1310-73-2
2-Ethoxyethanol	C4H10	90	-70	135	110-80-5
2-Ethylene glycol	C2H6O2	62	-12.9	197.3	107-21-1
Ethyl alcohol	C2H6O	46	-114	78.2	64-17-5
Propofol (2,6-Diisopropylphenol)	C12H18O	178	18	256	2078-54-8

 

Table 2: Physical properties of chemicals used in synthesis of Propofol Process

 

Based on the global demand ⁽¹⁾ unformulated propofol can be produced using modular plants. Validity of process patent ⁽⁸⁾ due to similar chemistries being on the public domain might need a review. 

 

Commercialization:

 

Each product’s raw materials and intermediates along with physical and chemical properties and nuances of process equipment need to be exploited. Any experienced process design chemist and/or chemical engineer, i.e. part the village ^(1,2,3,4,5) once exposed to the chemistry in the lab can create simple processes if they are well versed in exploiting social behavior of chemicals and process equipment. It is emphasized again that laboratory just shows the pathway. Imagination, creativity and experience of chemists and chemical engineers are of vital importance ^(1,2,3,4,5). Impact on environmental conservation can be effortless and efficient. 

 

In each of the cases discussed above every creative and imaginative chemical engineer and chemist with the help of village ^(1,2,3,4,5) can easily select and design a manufacturing process which can be modulated to meet variable production demand and even used to produce other products if equipment modifications are needed.

 

We have to accept and acknowledge chemical processes have a definition to be a batch process or a continuous process. Chemistry that can be processed in any processing equipment that is not specifically designed for the process is a batch process. Generally in such processes intermediate products are held over time for further processing. Equipment specifically designed to produce a product and is processed without being held for time for the next reaction process step operate 24x7x350 hours per year is a continuous process. Claiming a lab or plant process where intermediate reaction product is held to be processed for some time is a batch process and calling it a continuous process is mis-representation of reality. 

 

It is emphasized that we with the inclusion of village ^(1,2,3,4,5) have to review each process chemistry and by exploiting their chemical and physical properties can commercialize excellent environmentally friendly economic processes.  

 

Girish Malhotra, PE

 

EPCOT International 

 

References:

 

1.     Malhotra, Girish Profitability through Simplicity  

2.     Malhotra, Girish Malhotra, Girish Active Pharmaceutical Ingredient Manufacturing: Nondestructive Creation De Gruyter April 2022

3.     Malhotra, Girish Chemical Process Simplification: Improving Productivity and Sustainability John Wiley & Sons, February 2011

4.     Malhotra, Girish  Chapter 4 “Simplified Process Development and Commercialization” in “ Quality by Design-Putting Theory into Practice” co-published by  Parenteral Drug Association and DHI Publishing© February 2011

5.     Malhotra, Girish: The Process Development Triumvirate: Profitability Through Simplicity, March 24, 2026

6.     Pramanik C. et.al. Commercial Manufacturing of Propofol: Simplifying the Isolation Process and Control on Related Substances Org. Process Res. Dev. 2014, 18, 152−156

7.     Vinet, Laurent et.al. Process Intensive Synthesis of Propofol Enabled by Continuous Flow Chemistry Org. Process Res. Dev. 2022, 26, 2330-2336

8.     Chodankar N.K. USP 11,767,281 B2 Manufacturing and Purification Technology for High Purity Propofol September 23, 2023

9.     Coeuillas A. et.al. Process Intensified Continuous Flow Synthesis of Propofol December 24, 2025 

The Process Development Triumvirate: Profitability Through Simplicity

Why Chemistry, Properties, and Equipment Must Work Together from the Onset

Every chemical—whether a lifestyle-enhancing and/or life-extending product—has a theoretical and practical legacy and pathway through which it is developed, scaled up, and commercialized. 

Exploitation of the following triumvirate impacts the overall process, product quality, economics, and environmental outcome. 

•       Process chemistry (unit processes)

•       Sociochemicology (physical and chemical properties)

•       Process equipment (unit operations)

Paper chemistries (unit processes) show us the theoretical pathway. Laboratory experiments validate them. How the “VILLAGE” (chemist, chemical engineer, manufacturing, purchasing, and accounting) exploits these using the triumvirate to create an excellent process depends on collective imagination, creativity, and the ability to harness the mutual behavior of the physical and chemical properties (Sociochemicology) of raw materials, intermediates, and final products, along with the capabilities of process equipment (unit operations).

Once the village realizes the benefits and success of such collaborative efforts, they become committed advocates.

In my 60+ year career, I have been fortunate to work with and learn from members of such a “VILLAGE.” Thoughtful inclusion and application of the elements of the triumvirate have consistently resulted in economic processes. In many cases, capital investment was also reduced compared to processes where chemistries were forced into existing equipment—what I describe as “fitting a square plug into a round hole.”

Exploitation of Sociochemicology is of tremendous value. Learnings from reaction kinetics and thermodynamic properties must be fully utilized (as discussed in my books and blogs) ^1,2,3,4. Differences in solubility and density can reduce reaction volumes, leading to smaller equipment and lower capital investment. Solvent usage can often be reduced or eliminated, and overall productivity is generally improved.  

Triumvirate-based designs are simpler and more productive compared to designs where chemistry is forced to fit existing equipment. They also generally result in higher profitability.

Laboratories are excellent for proving chemical feasibility. However, translating this into a simpler and more economical process requires imagination, creativity, and full exploitation of Sociochemicological behavior along with appropriate use of process equipment. All elements of the triumvirate must be considered and integrated.

Paper chemistry is a good starting point. The laboratory can demonstrate feasibility, but it cannot replicate what imagination and the collective contribution of the village (chemists, chemical engineers, manufacturing, accounting, purchasing, and maintenance) can achieve. For every successful process, imagination and creativity are essential.

Process development typically begins in round-bottom flasks, and process schemes are demonstrated at the laboratory bench. Due to tradition, the elements of the triumvirate are often not fully exploited. This is due to equipment limitations, established practices, and initial resistance when new ideas are proposed. However, with success, skeptics often become strong supporters.

The following case illustrates this point (additional examples are discussed in my publications ^1,2,3,4.

A company, whose identity is not disclosed, successfully commercialized products using triumvirate-based thinking. Encouraged by this success, it developed and commercialized a continuous process that had not previously been conceived.

Every organic chemistry textbook discusses diazonium reactions and suggests that, due to their exothermic nature, they are generally carried out at around 0°C. The following reaction is well known:

R–NH₂ + 2HCl + NaNO₂ → RN₂Cl + NaCl  (1)

Due to the instability of the diazo intermediate, it is typically reacted immediately with subsequent reagents. However, breaking the reaction into steps suggests the following:

R–NH₂ + HCl → R–NH₂.HCl  (2)
R–NH₂·HCl + HCl + NaNO₂ → RN₂Cl + 2H₂O + NaCl  (3)

This stepwise nuance of chemistry was commercialized over 55 years ago by an assembled “village” as a continuous process. It operated at approximately 40°C for about 7,200 hours per year. Each intermediate was immediately converted to the next intermediate to the final product through subsequent reactions (sulfation, chlorination, amidation, etc.), followed by isolation and purification. Some patents discuss similar chemistries. If they were commercialized is not known.  

A batch methylation was converted to continuous process resulting is significant reduction of solvent use. Other chemistries can also be similarly exploited to create simpler processes. In many cases, solvent usage can be significantly reduced or eliminated. Several such examples are discussed ^1,2,3,4. We must challenge traditional ways in which chemistries have been and continue to be practiced.  

Learnings from these and other successes show that triumvirate-based approaches can be extended to a wide range of chemical processes. Yes, naysayers can be convinced—it often takes just one success. In my 60+ years in process development, commercialization, and manufacturing, I have seen many change their perspective.

The question we must ask ourselves is: “Is there an alternate way?”

To summarize, triumvirate-based designs are simpler and more productive than those that force processes into existing equipment. They generally deliver higher profitability. Such processes are inherently simpler, supporting the principle that: “Profitability is Simplicity.”

Girish Malhotra, PE

EPCOT International 

References:

1. Malhotra, Girish: Blog Profitability through Simplicity  
2. Malhotra, Girish: Chemical Process Simplification: Improving Productivity and Sustainability   John Wiley & Sons, February 2011
3. Chapter 4 “Simplified Process Development and Commercialization” in “ Quality by Design-Putting Theory into Practice” co-published by  Parenteral Drug Association and DHI Publishing© February 2011
4. Malhotra, Girish: Active Pharmaceutical Ingredient Manufacturing: Nondestructive Creation De Gruyter April 2022

SOCIOCHEMICOLOGY: Designing Chemical Processes by Exploiting the Social Behavior of Molecules

A Personal Note from Girish Malhotra

 

For more than sixty years, I have practiced Sociochemicology — the deliberate exploitation of the mutual behavior of chemicals to simplify manufacturing.

This is not theoretical chemistry. It is the product of decades of careful observation, experimentation, and disciplined thinking. I have seen countless processes burdened by unnecessary steps, wasted energy, and avoidable complexity. I have also seen the profound benefits when simplicity, creativity, and understanding of molecular behavior are applied intentionally.

I share this work not for recognition, nor to claim discovery, but to pass on what I have learned before I leave this planet. My hope is that others — chemists, chemical engineers, and curious minds — will engage with these ideas, challenge them, improve them, and carry them forward.

Science progresses not just through reaction mechanisms or calculations, but through insight, imagination, and disciplined observation. Sociochemicology is my attempt to capture that essence and make it practical.

If even a few minds are inspired to think differently, question inherited norms, and design processes more intelligently, then this work will have served its purpose.

For more than sixty years, I have practiced a method of process design that I later named Sociochemicology — the deliberate exploitation of the mutual behavior of chemicals to simplify manufacturing.

• It is not a new branch of chemistry.
• It is not theoretical abstraction.
• It is applied physical chemistry used intentionally to eliminate unnecessary process burdens.

Most process development begins with a reaction scheme and builds outward. The emphasis is on conversion, yield, and purity. Existing equipment is a facilitator rather than a strategic design variable. Product quality deviations are managed.

Sociochemicology begins differently. It asks:

How do these molecules behave together under realistic manufacturing conditions — and how can that behavior be used to eliminate steps rather than create them?

The Central Premise

Chemicals do not behave in isolation. They interact socially — through solubility differences, phase behavior, crystallization tendencies, density differences, acid-base relationships, thermal characteristics, kinetic preferences, and other physical property differences.

In many industrial processes, we ignore this “social behavior” during early design. As a result:

• We dissolve what we later must separate.
• We overreact and then purify.
• We neutralize only to re-acidify.
• We introduce solvents that complicate recovery.

Then we add equipment, controls, and validation layers to manage the complexity we created.

Sociochemicology reverses this logic. Instead of forcing chemistry and managing consequences, we allow molecular behavior to guide sequencing and staging from inception.

Profitability Through Simplicity

For decades, I have advocated what I call Profitability through Simplicity ⁽¹⁾. Not minimalism for its own sake, but disciplined elimination of non-value-adding operations.

Simplicity in manufacturing yields:

• Thoughtful capital investment
• Reduced energy consumption
• Fewer separations
• Less waste
• Minimal solvent use
• Shorter cycle times
• Improved robustness
• Lowest cost 

Yet simplicity is often resisted. Complexity creates institutional comfort. Departments form around managing problems.  Validation structures grow around inherited designs.  

Elimination can feel disruptive. But industrial progress rarely comes from adding steps. It comes from questioning 

why they exist.

Sociochemicology in Practice

Sociochemicology does not require exotic technology. It requires disciplined observation and creative application of physical chemistry principles.

It means designing processes around:

• Differential solubility rather than brute-force purification
• Controlled precipitation rather than evaporative concentration
• Selective crystallization rather than chromatographic rescue
• Mutual phase behavior exploited intentionally
• Equipment used as a behavioral amplifier rather than a containment vessel

In site-based chemistries such as Omeprazole, Phthalimide, Metformin, Modafinil, Gabapentin and other active ingredients, simplification did not come from discovering new reactions. It came from reordering steps, staging additions differently, and allowing inherent molecular tendencies to perform separations naturally ^(2,3,4).

The chemistry was known. The behavior was underutilized. The innovation lay not in reaction discovery, but in interaction management. Alternative routes to established processes needed to be exploited — and we did.

Why It Is Rarely Taught

 

Academic training emphasizes reaction mechanisms, kinetics, thermodynamics, unit processes and unit operations. These are essential foundations.

 

However, curricula often do not emphasize free thinking in process staging — the art of asking:

•       What happens if we change the order?

•       What if we avoid dissolving this component?

•       Can we precipitate selectively before impurity formation?

•       Can the equipment environment be used to influence behavior?

 

Industrial design frequently follows precedent. Once a route is validated, it becomes institutionalized.

 

Sociochemicology challenges inherited structure. It suggests that many “necessary” unit operations and unit processes are artifacts of early decisions rather than chemical inevitabilities.

 

Not Magic — Discipline

 

Sociochemicology ⁽¹⁾ is sometimes misunderstood as intuitive or anecdotal. It is neither.

 

It is rooted in:

         •        Solubility parameters

         •        Thermodynamic equilibria

         •        Acid-base interactions

         •        Mutual solubilities and insolubilities

         •        Mass transfer behavior

 

The difference is not scientific rigor — but emphasis. Traditional development asks: “How do we make this reaction work?”

 

Sociochemicology asks: “How do we make the entire sequence self-organizing?”

 

A Practical Test

 

Consider any multi-step API manufacturing process.

 

For each step, ask:

         1.       Does this operation exist because of intrinsic chemistry?

         2.       Or does it compensate for an earlier design decision?

 

If it is compensatory, simplification may be possible. Often the greatest improvements come not from new molecules or new platforms, but from eliminating what should never have been introduced.

 

The Future Opportunity

 

Artificial intelligence and modeling tools may facilitate and optimize defined process structures. However, optimization assumes that the structure itself is appropriate. Simplification requires something different -  deliberate understanding of mutual physical behavior and the willingness to question inherited laboratory sequences.

 

No algorithm replaces thoughtful interrogation of molecular behavior. Imagination and disciplined understanding of physical properties remain essential.

 

The opportunity ahead is not merely automation of existing complexity — but redesign grounded in behavioral exploitation. Sociochemicology provides a framework for that redesign.

 

Sociochemicology provides a framework for that redesign. It is not revolutionary chemistry. It is disciplined attention.

 

Invitation

 

I have practiced the principles of Sociochemicology since early 1960s, long before the term was coined. Many real-world applications are described in my published work and articles.

 

But the concept gains power only through discussion. If you believe a process step cannot be simplified, I welcome the example.

 

Progress begins with conversation. 

Editorial refinement support provided by AI tools.  

 

Girish Malhotra PE

 

EPCOT International

 

References:

 

1.     Malhotra, Girish Blog Profitability through Simplicity  

2.     Malhotra, Girish Malhotra, Girish Active Pharmaceutical Ingredient Manufacturing: Nondestructive Creation De Gruyter April 2022

3.     Malhotra, Girish Chemical Process Simplification: Improving Productivity and Sustainability John Wiley & Sons, February 2011

4.     Malhotra, Girish  Chapter 4 “Simplified Process Development and Commercialization” in “ Quality by Design-Putting Theory into Practice” co-published by  Parenteral Drug Association and DHI Publishing© February 2011