Agent Orange

In the words of Austrian psychologist Sigmund Freud: "If it is admitted that art and science have the power to do good, then it must also be admitted that they have the power to do harm." Personally, I am not the most enthusiastic advocate of Freud's work. I disagree with many of his theories pertaining to sex, the unconscious mind, and hysteria. However, I believe there is hardly anything truer than his statement - science, especially chemistry, has the potential to bring both good and bad into this world - order and chaos, construction and destruction - and it is this potential that worries me at times. My friends, I am about to take you through a brief history of the chemical warfare that occurred during the Vietnam War (1960 - 1975). More specifically, I am going to talk about the herbicide and defoliant known as Agent Orange. What you are about to read highlights both the beauty and the atrocity - the iniquity of Agent Orange and its everlasting mark on history.

Enough with the ominous and pessimistic introduction, and onto the chemistry! Now, what exactly is Agent Orange? Agent Orange is the code name for a powerful herbicide and defoliant developed primarily for military usage. The military first used Agent Orange during the Vietnam War, mainly from 1961-1971. The herbicide is called "Agent Orange" because during the war, it was shipped in orange-striped barrels. As you can probably guess, Agent Orange was used to kill plants and crops on the ground, in addition to defoliating the leaves off of plants and forest trees. Basically, it killed a lot of plants and trees. It is estimated that nearly 20 million gallons of Agent Orange were sprayed over various parts of Vietnam. 

U.S. military planes spraying Agent Orange over miles of Vietnam's forests. 

Now, what is so bad about Agent Orange? What makes it so harmful? We must first talk about the chemical makeup of Agent Orange. Agent Orange is a 50:50 mixture of two chemicals known as 2,4-D (2,4-dichlorophenoxyacetic acid or C₈H₆Cl₂O₃) and 2,4,5-T (2,4,5-trichlorophenoxyacetic acid or C₈H₅Cl₃O₃). These two compounds can act like plant hormones. In case you forgot what a hormone was, a hormone is essentially like a chemical messenger that transports signals from one cell to another. Hormones can affect the structure of organisms, such as the rigidity of cell walls in plants. By acting like false plant hormones, 2,4-D and 2,4,5-T destroy plants by interfering with their normal metabolism. When exposed to these substances, plants can experience sudden, uncontrolled growth, kind of like a plant cancer. Plants can't receive enough nutrients when growing uncontrollably, and eventually shed their leaves and die.

2,4-D

2,4,5-T

Agent Orange not only harms plants, but humans as well. This is due to the fact that the synthesis of Agent Orange produces dioxins as a byproduct. Dioxins are a group of chlorinated organic chemicals with similar structures. Some dioxins are extremely toxic while others aren't. Why is this? Well, the potential harm a dioxin can induce depends on the number and the position of the Cl atoms attached. The dioxin that is the synthesis's byproduct is known as 2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD. Unfortunately, TCDD has been described by some scientists as "perhaps the most toxic molecule evry synthesized  by man." Since dioxins are carcinogenic to humans, it is important to note how dioxins enter the human body. Dioxins such as TCDD are emitted into the atmosphere and land in water or on ground. In water, dioxins bind strongly to small particles and other organic compounds. These molecules are inhaled by microorganisms, and eventually the dioxins will find their way up the food chain until we eat an organism with dioxin in it. Dioxins that land on the ground strongly bond with the organic compounds in the soil, and therefore any present groundwater isn't contaminated. Humans are also exposed to dioxins by air, especially when they come into contact with dioxin-containing herbicides. Dioxins are almost insoluble in water and have a high affinity for lipids (fat), such as the fat stored in the human body. Lastly, dioxins are highly stable due to their near perfect symmetry. Another group wrote about the symmetry of dioxins and Agent Orange on its blog.

Now let's analyze the structure and synthesis reactions of Agent Orange and its compounds. This part will be more conceptual. For me, seeing pictures sometimes helps me more when it comes to understanding certain material. It's helpful to see which atoms move where. Also, there's that saying that a picture is worth a thousand words...so I guess I could just have two pictures instead of this blog post...anyway, as I mentioned before, Agent Orange is just a one-to-one mixture of 2,4,5-T and 2,4-D. Dioxin is the unintentional byproduct of 2,4,5-T synthesis. The picture below shows the step-by-step synthesis of 2,4,5-T. Note that a key step in the formation of 2,4,5-T is the synthesis of 2,4,5-trichlorophenol.

Synthesis of 2,4,5-trichlorophenol, which is
important in the formation of 2,4,5-T. 

On the left is the synthesis of 2,4,5-T, a defoliant and herbicide used to Agent Orange.

The picture on the left shows each step of the production of the byproduct dioxin or 2,3,7,8-T. Notice how the Cl atoms are attached to the molecule at the 2nd,3rd,7th, and 8th Carbon atoms in each ring. This is where it gets its name from.

The New York Times published an article titled "Remedying the Effect of Agent Orange" in August 2012. The article talked about the horrors of Agent Orange's effect. The effects of Agent Orange are still seen today. Mothers in Vietnam still have birth defects. Their children are mutated. Dioxin-induced cancer is still present. The NY Times article stated that if we really want to help the victims of the war, :we should begin by financing a more widespread cleanup and by providing serious support to the families struggling with the birth defects that are one of the legacies of our invasion of their country."

Vietnamese army captain who was
exposed to Agent Orange during the
Vietnam War. 

Before dioxin poisoning.           After dioxin poisoning. 

I am sorry if you finished reading this post with a feeling of sadness or disgust. Unfortunately, this is life, and the reality of it can sometimes be overwhelming. I hope you were able to learn about the chemistry of Agent Orange and its mark on history. Unfortunately, Mr. Freud was right: if science has the power to help others, it has the power to do harm others. Feel free to comment about anything, and as always, have a nice day.


By: Max Lauring