The present author would like to emphasize that the following is in the context of harm reduction. Heroin is a very dangerous drug that should be avoided. That being said, some may have seen discussion regarding #3 and #4 forms of heroin. In the paragraphs that follow I hope to detail their difference, which essentially comes down to stages of processing.
Opium is the original opiate. Opium is derived from the sap of poppies and primarily contains two molecules of interest: morphine and codeine. As can be seen, both morphine and codeine share a similar molecular structure. They possess three planar 6-carbon rings connected on one side by an oxygen. A nitrogen and some carbons extend outward from their flat structures. Around 200 years ago, morphine was first isolated and used as a treatment for opium addiction. This treatment plan was abandoned as the addiction potential of morphine was soon discovered.
Around 100 years ago, history repeated itself when Bayer Pharmaceuticals began the commercial manufacture of heroin. Heroin production involves the diacetylation of morphine. Diacetylation occurs when the two hydroxyl (-OH) groups on morphine are switched for two acetyl (CH3CO) groups. Heroin was heralded as a hero, one that could cure addiction to morphine. However, this treatment plan was abandoned as the addiction potential of heroin was soon discovered.
As stated previously, heroin is produced when morphine’s two hydroxyl groups are acetylated. What forms is an unrefined product known as #3 heroin. This product may be acceptable for use in a pill. However, as it is not water soluble, unrefined heroin is unacceptable for those who are using via alternative routes. For instance, in the absence of further chemical reactions, #3 heroin is not suitable for injection.
In order to prepare #3 heroin for injection, one needs to alter the drug. Further processing of #3 heroin involves the addition of a proton to heroin’s nitrogen (amino group), forming #4 heroin. This reaction is analogous (though moving in the opposite direction, molecularly) to what occurs in the formation of crack cocaine from cocaine.
One may have heard of people using citric acid packets in their water when preparing to inject #3 heroin. However, users should take caution here as the injection of acidic solutions can be very dangerous. Citric acid is strong enough of an acid to protonate heroin’s amine group, forming some water-soluble #4 heroin. When preparing an injection of #3 heroin, large amounts of citric acid may go unreacted. Injecting acidic solutions will easily damage venous tissue and can potentially collapse vessels. Abuse to your circulatory system is a serious risk that should not be minimized. If you must use, please do so with care and research everything that is put into your body.
In the US, users of heroin commonly encounter a form that readily dissolves in water. Drug manufacturers have completed the large scale protonation of #3 heroin, using an acid such as hydrochloric acid, to the more user-friendly #4 heroin. This is perhaps why black tar heroin often smells of acetic acid (vinegar).
Again, the above information is offered in the context of harm reduction. Under no circumstances should one encourage heroin use. Extreme concern should be expressed when friends or family are known to be using heroin. Heroin is a very dangerous, addictive, and deadly drug. Thanks for reading.