Here is some more interesting real-world chemistry of turpentine, which is mostly a mixture of the pinenes, which comes in alpha and beta forms. An old practice of veterinarians used turpentine and iodine to treat wounds in livestock. Many who have read All Creatures Great and Small by James Herriot could recall this being described to disinfect a wound on a horse’s hoof. In my own case, while I was a graduate student at Berkeley, T. Ross Kelly of Boston College was on sabbatical in the Heathcock group (he had been Clayton’s first graduate student, and as lore has it, the first PhD produced by a professor is always the best) and worked in my lab. Ross told me about the iodine / pinene reaction that he used as a demonstration of ring strain in his organic chemistry lectures. He demonstrated it in our hood, and at various times in my teaching career, I have also done the demonstration in my lectures.
Below is a structure of alpha-pinene, which reacts with iodine to form an iodonium ion. Because of the strained adjacent 4-membered ring, this intermediate undergoes a rearrangement, with multiple possible intermediates and products. Similar reaction chemistry can be written for beta-pinene, which is just an alkene isomer of alpha-pinene. The strain of cyclobutane is about 26 kcal/mol, nearly as much as the strain of cyclopropane, and all of these rearrangement reactions release the strain in the pinene, which is evolved as heat. In the use of iodine and turpentine in wound treatment, there is not only the disinfecting power of the iodine (well-known in the classical antiseptic, tincture of iodine – an ethanol solution), but also the heat evolved, which can help sterilize a wound. In the case of performing this reaction as a demonstration, the heat evolved from the reaction serves to vaporize the excess iodine, leading to a purple cloud.
Here is a quick video clip that shows this reaction in action:
https://lnkd.in/gPQyjCSp
Originally, turpentine was obtained from pine tree resin. It could be a challenge to locate authentic turpentine in the modern world. It formerly was used as a paint thinner, but any volatile hydrocarbon can serve that role, so more likely the paint solvents one would find at home improvement stores these days is a petroleum distillate.
M.Sc., Ph.D., Research Associate, Prof. H.S. Srivastava Foundation for Science & Society, GGSIPU
1moGreat opportunity! Please find time and grit to give point-wise answers to the following questions/concerns: 1. How many scientists are required for a sustainable life? 2. What instruments/methods are required to make a scientist who can maintain a sustainable livelihood and longevity of mother nature? 3. How much time is required to reach suitable physical and mental growth to maintain a sustainable livelihood and longevity of mother nature? Best Vikas