How is opium extracted from poppies?
The ancients discovered opium poppy pod could soothe emotions and alleviate pain. Sumerians referred to it as plant of joy. Perhaps our ancestors experienced an even more intense euphoria, when they crushed pod and drank its juice by chance. Subsequently, pod was crushed to obtain juice that was filtered and then boiled down into a viscous paste. This might be the most ancient opium.
Another method of obtaining more potent opium was invented later. A vertical superficial incision was made on the poppy pod with a knife in the afternoon. White sticky sap slowly oozed out. It was oxidized and dried into a brown raw opium overnight. It was crucial not to cut too deeply, as the sap would flow too quickly and drip to the ground. Farmers scraped off the solidified sap with knives in next morning. Sap could be collected multiple times from a single poppy pod until it withered.
Raw opium (heroin No. 1) is pressed into bricks or balls for easier storage and transportation. Its main components are water, resin, and dozens of alkaloids. The three most abundant alkaloids are morphine, codeine, and noscapine. Morphine and codeine are opioid alkaloids that relieve pain and suppress nervous impulse. Raw opium sometimes emits an ammonia smell. It may be that nitrogen-containing alkaloids are broken down by microbes. In China and Southeast Asia, raw opium solution is filtered to remove impurities and then boiled with various spices to produce prepared opium with higher morphine content.
How is morphine extracted from opium?
Although other alkaloids such as codeine have similar functions, morphine is the most abundant and potent component leading to opium's miraculous effect. An acid hydroxyl group (PKa≈10) in benzene ring makes morphine soluble in alkaline solutions where other alkaloids precipitate, because they do not have such structure.
Mixing with lime is the simplest and most popular way. Raw opium is melted with hot water. Then calcium hydroxide (lime) is added to produce soluble morphine salts and a slurry-like precipitate that contains proteins and other alkaloids. They are separated by a filtration device. Some morphine salt is in precipitate due to their high concentration, so filtration and dissolution must be repeated several times.
Morphine salt is also soluble in acid solution, since its nitrogen atom will be protonated (PH<8, PKa≈8) to result in a charged molecule. It is usually acidified by NH₄Cl to achieve an appropriate medium PH (8~10, neither too high nor too low) for morphine precipitate. Then it is filtered and dried to get crude extract (heroin NO.2).
How to convert morphine into heroin hydrochloride (NO.4, China white)?
Heroin was invented by scientists to replace the addictive morphine, but they shoot themselves in foot ultimately. Heroin is the acetylated morphine that is more lipophilic and easier to enter cells and cause addiction.
A slight excessive acetic acid or anhydride is added to morphine solution. It is heated on a stove to ensure reaction fully proceeds. Sodium carbonate is used to neutralize acid until no bubble appears. The black tar heroin base precipitates at the bottom of container. Other substances are mixed with them to get heroin NO.3 that looks like brown sugar and contains 50% caffeine and only 20-30% heroin. Drug users generally put it on a tin foil and smoke it with the help of a lighter.
Repeated dissolution and precipitation are necessary for further purification. The brown heroin base is dissolved in dilute hydrochloric acid. Impurities are absorbed by activated carbon and filtered out with cloth. White heroin base is precipitated from clear filtrate by ammonia. Finally, it is acidified to acquire water-soluble heroin hydrochloride (heroin NO.4 or China white). Its purity is at least above 80%, sometimes even as high as 98%. Drug dealers add some white impurities to increase profits and reduce risks, because directly smoking or injecting pure heroin No.4 can easily lead to death.