How nicotine is made in e-liquid
As companies start selling e-liquids made of what they call tobacco-free and synthetic nicotine, the debate about nicotine is also getting fiercer. The source of nicotine provides manufacturers with sales arguments and some plausible legal denials, as most regulations link nicotine to tobacco. Back to artificial synthesis, is it a solution?
In this market, various brands from the food industry to cosmetics have launched organic natural, non-GMO-labeled e-liquid. Is it a step forward to return to synthetic or laboratory-made substances?
Nicotine is a molecule, an alkaloid, which is naturally produced by some Solanaceae and we often call it nicotine. Solanaceae includes not only tobacco, but also peppers, tomatoes, potatoes, eggplants or petunia. Among these plants, tobacco (Nicotiana tabacum) is one of the richest nicotine plants, accounting for 8% -14%, which is why it is used, dried and burned in cigarettes.
Nicotine and tobacco have been together for more than a century. Nicotine can be psychologically irritating to smokers and addictive. In burning cigarettes, the tobacco leaves are basically not treated in any way other than dry. The bright tobacco leaves are ready to be harvested when they turn yellow-green, their nicotine content reaches its maximum, and they are marinated to a deep golden color with a mild flavor. Tobacco companies use additives to improve this taste, and the use of this additive is controversial and is considered to be a cigarette addictive enhancer.
Nicotine was also used as a pesticide after World War II, but since the chemical industry provided other cheaper molecules, nicotine use has diminished.
Liquid nicotine from plants
In e-liquid liquids, people no longer use tobacco leaves, but instead use liquid nicotine solutions, a product usually obtained from tobacco leaves.
Nicotine, 3- [1-methylpyrrolidin-2-yl] pyridine, contains chiral carbon as chemists call it. This molecule usually has two non-superimposable structures, called enantiomers. They have the same chemical formula, but their atomic positions may be different, so that two molecules cannot overlap, such as left and right hands; mirror images or enantiomers of each other. In chemistry, these two enantiomers are S- and R-nicotine.
Since S-Nicotine rotates plane polarized light to the left (left-handed) and R-Nicotine rotates to the right (right-handed), S-Nicotine and R-Nicotine can be optically distinguished. A recent basic concept in stereochemistry, a mixture of two enantiomers coexisting in a ratio of 1: 1 is called racemity (the deviation of plane polarized light is zero). In the case of nicotine, the racemic mixture is called RS-nicotine.
In fresh tobacco, the rank of alkaloids is usually composed of 93% S-nicotine 1, 3.9% S-anatabin 2, 2.4% S-nornicotine 3, and 0.5% S-anabatamine 4.
The extraction of alkaloids is achieved by crushing crops with organic solvents and distillation. Nicotine and alkaloids are soluble in solvents such as alcohol, chloroform, ether, petroleum ether, kerosene and water. Microwave heating and solvent mixing can improve the extraction rate of nicotine, shorten the extraction time, and ensure that the product purity reaches 99.9% pharmaceutical grade.
Another method is to use a salt treatment and convert the liquid to sulfate. This method requires bleach to remove impurities. The sulfate is then reduced to a usable form with a reagent. The bleach appeared to be clearer and was mistakenly considered to be of higher purity.
Chemical Synthesis of Nicotine
Nicotine is a comprehensive challenge for chemists. Until recently, the disadvantage of synthesizing nicotine was cost, and the most economical way to obtain the desired enantiomer of nicotine was by separation of a racemic mixture (RS-Nicotine). Another step, recrystallization, will allow selection of the desired enantiomer (e.g. S-) and production of S-nicotine.
The main problem with racemic mixtures is that the presence of 50% of non-psychoactive R-nicotine and 50% of psychoactive S-nicotine separates the potential activity of e-liquid into two parts compared to natural tobacco extract.
Since the label only shows nicotine content, the strength of the racemic mixture of synthetic nicotine is 10 mg / ml, which is actually equivalent to 5 mg / ml of e-liquid.
After purification, the freshly synthesized liquid is colorless, as is the nicotine extracted from tobacco leaves. The brown color of liquid nicotine is a natural process produced by exposure to light, heat, and oxygen, and sometimes it occurs in the dark, even in sealed bottles. Nicotine tinting is purely "make-up", and a clearer liquid does not imply purer or higher quality.