This interview was inspired by my latest infatuation with my etsy shop. My inspiration for starting an ‘store’ on etsy was Inedible Jewelry. They are a polymer clay jewelry business in the lovely city of Charlottesville, making replicas of everyday foods with PVC. The ladies of Inedible Jewelry, Jessica and Susan Partain, are at our local farmer’s market every weekend selling their latest miniature creations. Taking the opportunity to see their studio and learn more about the chemistry behind polymer clay, I set up an interview with Jessica Partain in her workshop (see picture to left).
I interrupted her in the middle of placing holiday orders, in her studio filled with doll-house sized desserts, drinks, fruits, vegetables, etc. The main material used to make these bit-sized creations is PVC. I started the interview asking about the chemical concerns with PVC over the past decade. Jessica explained: “While the formulation of PVC itself has not changed, both of the polymer clays that I work with (97% Premo, 3% Sculpey, both manufactured by polyform products) were reformulated in 2008 to be phthalate-free and lead-free.” Phthalates, which are also endocrine disruptors, used to be a concern for the sculptors before the reform because baking the clay would release them, consequently allowing them to be inhaled by the artist. Jessica also explained: The clay she uses is also ASTM certified, making the product safe. “They’ve run it past medical experts and biochemists looking specifically for potentially harmful interactions between the material and the artist.” This made me proud of my fellow medical experts and biochemists, doing good in the world.
Jessica and Susan have also always used a separate toaster in a well-ventilated room for their polymer baking, making creations such as the cupcake earrings to the right. They use a separate toaster to ensure that they
would not combine their cooking with their polymer. One concern that still remains is when the clay is burnt, from baking for too long or from baking at too high a temperature – releasing toxic HCl gas.
As a loyal customer, I asked her: “What do you do with annoying customers like myself, who also ask all these difficult chemistry questions before a purchase.” She answered: “Well, you are one of two people asking me these questions in past 22 years; and the other person who asked did not have much basis for her questioning.” I felt like a major nerd at that moment – 8 years of intense science back ground can do that to you.
Although most customers do not ask about the chemistry behind polymer clay, many worry about the metals used in the jewelry. I then asked “Is this because they are worried about the toxic chemicals in metals?” That was strike two for Nerd Mana. The real reason is because many people are allergic to certain metals. To combat this problem, Inedible Jewelry uses 925 Sterling Silver for their necklaces.925 indicates the silver is 92.5% silver, and 7.5% copper. Jessica explained that the copper allows for 925 Sterling Silver to hold its shape because 100% silver is too malleable. All her metals are nickel free to avoid allergic reactions that lead to inflammation.
AGC loves the work of Inedible Jewelry and is impressed with their knowledge of chemistry and toxicology as it applies to their work. We all have a necklace with a polymer clay pendant. So far our collection includes: a peppermint, a gingerbread man, and a rainbow cake (mine!). The equally festive peach pies are pictures to the left where each miniature peach slice is crafted by hand.
Written by Mana Sassanpour
This figure is taken from Green chemistry: state of the art through an analysis of the literature by V. Dichiarante, D. Ravelli and A. Albini. Green Chemistry Letter and Reviews Vol. 3, No. 2, June 2010, 105-113.
Shake it up: A greener method for upset tummy medicine.
Saturday, December 17th, 2011André, V, A Hardeman, I Halasz, RS Stein, GJ Jackson, DG Reid, MJ Duer, C Curfs, MT Duarte and T Friščić. 2011. Mechanosynthesis of the metallodrug bismuth subsalicylate from Bi2O3 and structure of bismuth salicylate without auxiliary organic ligands. Angewandte Chemie International Edition http://dx.doi.org/10.1002/anie.201103171.
Synopsis by: Audrey Moores and Wendy Hessler, Dec 15, 2011
This sounds like a kitchen recipe: mix A with B, add a few drops of water, a pinch of salt and then shake. Except, researchers followed these simple directions in a laboratory to make the main ingredient in the popular stomach and intestinal remedy sold under the brand name Pepto-Bismol.
To make the drug this new way, they mixed the two main dry ingredients then added the rest and vigorously shook the paste in a special shaker. The breakthrough – an important step forward in the emerging field of mechanochemistry – uses less energy and solvent than the current way the drug is produced. And it creates no harmful by-products.
This discovery is showing that using simpler chemistry methods can improve processes as complex as drug synthesis and also aids understanding of how drugs work.
Context
The image of chemistry is intimately linked with the idea of mixing together liquids. But a new field of chemistry – namely mechanochemistry – proposes to make molecules by mixing solids without adding copious amounts of liquid solvents.
In mechanochemistry, the reagents are loaded into a small cylinder with two metal or ceramic balls. This cylinder is shaken very fast to allow proper mixing. The advantages of this technique are multiple. The products are collected pure, the reactions proceed faster than in solution, and less energy is required to perform the mixing compared to what is needed to heat large amount of solvents.
Variations of this method include addition of a few drops of solvent or a very small amount of salts. This permits the use of slower shaking, thus reducing energy use even more.
Pepto-Bismol is a popular stomach and intestinal relief medication. It is composed of a metal called bismuth and aspirine. To be active, bismuth and aspirine have to form chemical bonds together.
Currently, the drug is made by mixing water solutions of these two ingredients. After reacting, the excess water is removed, which costs energy, time and money. Previous efforts to find simpler, less wasteful, mechanical ways to manufacture the compounds have failed.
This bismuth-aspirin drug has been used for more than a century, yet chemists do not know exactly what its chemical structure looks like when the active ingredients combine. This has limited understanding of how the drug functions in the stomach.
What did they do?
A group of researchers from Cambridge, United Kingdom, wanted to improve the existing synthesis of a pharmaceutical group of compounds called bismuth salicylates. The most well-known variety is bismuth subsalicylate, the active ingredient in Pepto-Bismol, an over-the-counter medicine used to treat nausea, heartburn, diarrhea and other stomach and intestinal symptoms.
They were looking for a way to make the desired bismuth subsalicylate using a method that was more energy efficient, faster, yielded fewer harmful byproducts and used less solvent than the current way to make the drug.
Instead of first dissolving the two key ingredients – bismuth oxide and aspirine – in liquid solvents and then mixing the two fluids together, the researchers chose a simpler method. They mixed the dry powders in a mechanochemical mill.
It was not the first attempt to produce this drug in such a simple fashion, but past trials were met with little success. This time, the research group added a few drops of water and a pinch of salt. During ingredient shaking, the presence of the water and the salt enabled the formation of the drug in very high yields.
They tested different ratios of bismuth oxide and aspirine, different volumes of water and a variety of salts. After each attempt, they identified the products produced during the reaction.
What did they find?
The researchers first added a few drops of water to the bismuth oxide and aspirine powders. This helped the reaction and products did form, but none were the active ingredient bismuth subsalicylate they were looking for.
They redid the experiment adding a little bit of salt with the water to the powders. A series of different salts were tested. They discovered that potassium nitrate and ammonium nitrate were very efficient in promoting the reaction and afforded the desired drug in high yields.
The reason why the addition of water and salt is required is not completely understood, but the researchers believe that it helps the molecules organize and “find their place” in the final molecular architecture.
What does it mean?
By testing a new method of mixing ingredients, this group of chemists was able to produce a commercially important drug using less energy and solvent. They also are the first to identify the chemical structure of a compound similar to bismuth subsalicylate.
The discovery of this new synthetic method is important because it opens the way toward more energy efficient and less polluting drug fabrication. The chemists only had to mix two essential ingredients with tiny amounts of water and nitrate salts – less than 5 percent. Interestingly, these salts do not seem to mix with the final product, which allows for easy separation in the end. Also, this new process generates only water as a by-product. It is thus compatible with drug synthesis.
The secondary discovery of the compound’s chemical structure may seem surprising. Although it has been known for more than a century that the ingredient in Pepto-Bismol is active, the actual way it works is still unclear. In fact, no chemist had isolated and identified the three-dimension chemical structure of any bismuth salicylates. It is a little bit as if engineers were trying to understand the way an engine works without having the knowledge of the shape of its mechanical pieces.
In this study, the researchers were able to decipher the structure of a compound very close to the ingredient bismuth subsalicylate found in over-the-counter medicine. This is a vital step towards understanding the biological activity of this much-used drug. This discovery was possible because the method afforded an unusually pure product, another common advantage of mechanochemistry.
The use of mechanochemistry at a production scale has been demonstrated, for example, on the synthesis of an anti-inflammatory drug/carrier composite. This new discovery may thus lead to a more optimal production of Pepto-Bismol and other medicines. Read more science at Environmental Health News.
Tags: greener process, investment in green chemistry, replacements, solvents
Posted in Commentary | No Comments »