220px-FountainSpringsWintergreen.pngConclusions

When I decided to embark on investigating the natural synthesis of aspirin from wintergreen oil I was immediately surprised by the lack of my general knowledge about the well known drug. I was intrigued by its history and ancient roots, and found the discovery and patenting of the compound a real insight into pharmaceutical research and marketing. In discovering the petrochemical source for this pharmaceutical, it became obvious that this was an ideal candidate for my organic chemistry Green Project.
Once I had decided on my subject, the method of presentation for this project eluded me. I toyed with the idea of a poster, but rightly decided this was not going to give me enough room to explain the two processes. I eventually decided to create a wiki page and video the experiments for a more personal touch. There was also the factor that I was keen to actually see these experiments run and see how difficult or easy these were in practice.
The green chemistry Principles addressed using these processes were :-

· Prevention
It is better to prevent waste than to treat or clean up waste after it has been created.
This principle is addressed in the greener process with the use of simpler compounds and more benign waster products that can be recycled
· Less Hazardous Chemical Syntheses
Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
The use of benzene is obviously far more hazardous than the wintergreen oil. I was not allowed to run the current process due to the hazardous of the reagents and the lack of appropriate facilities to run the experiment.
· Safer Solvents and Auxiliaries
The use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used.
The use of acetic acid rather that Phosphoric acid or Sulphuric acid is inherently more innocuous. The common name for acetic acid is vinegar.
· Use of Renewable Feedstocks
A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.
Using Wintergreen oil extract from a plant is a renewable source as oppose to benzene derived from petrochemical source.
· Design for Degradation
Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment.
Aspirin as the end product can be readily turned back to methyl salicylate with acyl substitution.
· Inherently Safer Chemistry for Accident Prevention
Substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical accidents, including releases, explosions, and fires.
Although some of the reagents are lachymators, the current process chemicals require far more care in handling. Benzene is a known carcinogen.

The project design started with the project proposal. After some extensive research, I found two experiment procedures that seem to fit the best for the project. The history and current process research ended up being more difficult to complete. There are absolutely hundreds of different ways to produce salicylic acid from benzene, and no particular process seemed to be in enough detail for me to do the proposed metrics. Bayer documentation does not list the waste product quantities and exact yield , so I decided to abandon the idea of providing some metrics to quantify the green process improvements.


The experiment went really well with the details of each of the processes tying in neatly with the Organic chemistry syllabus. I had real life examples of esterifcation, acetylation and nucleophillic addition reactions. I was also struck with the pure simplicity of the greener process. The experiments were carried out with little problems with the exception of the first trial with the methyl salicylate to salicylic acid. I inadvertently used the HCl instead of the NaOH in the first step. Of course there was no reaction, but I put it down to camera nerves!
Overall, I am pleased with my project but as with anything like this you can go on forever finding other things to add to the assignment. If I had a couple of months more, I would really like to run the current process experiment at a specialized facility, and I would be able to actually quantify the metrics myself and produce a comparison. I also found the reverse reaction documented and would have liked to run this as well. That being said, with the resurgence of aspirin as a “cure all”; the latest research identifies aspirin as a significant tool against bowel cancer (Rothewell, 2010), a greener, more renewable manufacturing process needs to be adopted.


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