Nitroglycerin, a substance initially known for its explosive properties, has undergone a remarkable evolution over the years. What began as a volatile discovery in a Basel kitchen in the mid-19th century has since transformed into a crucial component in the treatment of various heart-related conditions. In this comprehensive exploration, we will delve into the intricate history and multifaceted journey of nitroglycerin, uncovering the pivotal moments, brilliant minds, and scientific breakthroughs that have shaped its diverse applications.
Christian Friedrich Schönbein, a German-Swiss chemist who, in 1846, unwittingly ignited the fuse to a series of explosive revelations. While conducting experiments in his Basel kitchen, Schönbein spilled a mixture of sulfuric and nitric acids onto his countertop. In a moment of serendipity, he grabbed the nearest cloth, a cotton apron, and draped it over the stove to dry. Little did he know that this simple act would lead to the discovery of nitrocellulose, the world’s first nitrate explosive.
Nitrocellulose, an accidental creation, would significantly impact society in the subsequent century. Initially used as guncotton, it offered a viable alternative to traditional gunpowder in firearms. Later, in 1869, it was ingeniously combined with camphor by American inventor John Wesley Hyatt to create celluloid, the first commercially effective plastic. Celluloid played a pivotal role in the nascent film industry, as movies were filmed on this versatile material. However, due to its high flammability, cellulose acetate “safety” film eventually replaced celluloid in the 1950s, prompted by several theater and film warehouse fires.
The year following Schönbein’s explosive discovery, at the University of Turin, Italian scientist Ascanio Sobero, under the guidance of French chemist Théophile-Jules Pelouze, embarked on a journey that would lead to the creation of nitroglycerin. Mixing nitric-sulfuric acid with glycerine, Sobero unwittingly unleashed a powerful force known as nitroglycerin, a high explosive with unparalleled destructive capabilities.
“Low explosives,” such as nitrocellulose and gunpowder, merely burn or detonate quickly. In contrast, “high explosives” like nitroglycerin explode, chemically breaking down the substance as an explosive shockwave travels through it at supersonic speeds. Nitroglycerin’s industrial applications revolutionized mining, as it delivered three times the energy of gunpowder, twenty-five times faster. However, there was a significant caveat: nitroglycerin was highly unstable, capable of exploding with minimal provocation. The production of nitroglycerin was fraught with peril due to the exothermic nature of the reaction involving glycerine, nitric acid, and sulfuric acid—a reaction generating enough heat to detonate the explosive. Remarkably, Sobero, the creator of nitroglycerin, was deeply apprehensive about its industrial use, vehemently arguing that it could never be safely regulated.
In stark contrast to Sobero’s reservations, Alfred Nobel, a fellow student of Pelouze, recognized the unparalleled potential of nitroglycerin. In 1864, alongside his brother Emil, Nobel transformed their family’s abandoned weapons factory in Heleneborg, Sweden, into a facility dedicated to producing the volatile explosive. To mitigate the inherent dangers of nitroglycerin, the Nobels implemented various innovative safety measures.
One such safety measure was to position manufacturing facilities on hillsides to allow nitroglycerin to flow more slowly due to gravity, preventing catastrophic explosions triggered by mechanical pumps. The chemicals involved in nitroglycerin production were mixed in large steel or lead vats, cooled by circulating water and air to prevent the exothermic reaction from spiraling out of control. Furthermore, the base of the vat could be opened to prevent a large tank of cold water from drowning the batch in case temperatures rose too high. To discourage workers from dozing off on the job, some factories even provided them with one-legged stools.
Despite the Nobels’ best efforts, nitroglycerin remained a highly volatile and deadly substance, resulting in numerous accidents and fatalities. Tragedy struck the Nobel family when Emil Nobel perished in a nitroglycerin explosion that leveled the Heleneborg factory in 1864. Further incidents, including the explosion of two nitroglycerin carriages in the Welsh settlement of Cwm-y-glo in 1869, prompted the British government to outlaw the production and transportation of the explosive within the British Isles through the Nitro-Glycerine Act. Other nations swiftly followed suit, reflecting the immense dangers posed by nitroglycerin.
Undeterred by these challenges, Alfred Nobel continued his quest to harness the power of nitroglycerin for the greater good. In 1867, Nobel turned to Kieselguhr, a chalky diatomaceous earth found near his business in Germany’s Krümmel hills, as an alternative material to absorb nitroglycerin. This resulted in the creation of a putty-like substance that was insensitive to ordinary shocks and could only be detonated with an explosive blasting cap. This groundbreaking invention, known as “Dynamite,” was both safer and more reliable than pure nitroglycerin. It not only made Nobel a wealthy man but also left an indelible mark on the fields of construction, mining, and warfare.
Nobel’s ingenuity did not stop with dynamite. In 1875, he developed an even safer mining explosive called “blasting gelatin” or “gelignite.” This explosive comprised nitroglycerin, wood pulp, and potassium nitrate. Nobel’s innovative prowess extended to weaponry as well, as he created Ballistite, a smokeless propellant for rifles and artillery, in 1887. These developments revolutionized both industry and warfare, enhancing safety and effectiveness in various applications.
The “Merchant of Death” Becomes a Nobel Laureate
Despite Nobel’s significant contributions to industry and science, his legacy took an unexpected turn. In 1888, an incorrectly published obituary dubbed him a “merchant of death” who had “become rich by finding ways to kill more people faster than ever before.” This harsh portrayal deeply unsettled Nobel and prompted him to take action. In 1895, he established the Nobel Prizes, allocating his considerable fortune to honor achievements in chemistry, physics, literature, physiology and medicine, and peace. This act of philanthropy transformed Nobel’s image from that of a controversial industrialist to a benefactor of humanity, leaving an enduring mark on the world.
Nitroglycerin’s Medical Transformation
While nitroglycerin had been synonymous with explosives for many decades, its potential for medical use began to emerge in the late 19th century. Unusual observations made by explosives workers laid the foundation for its medicinal applications. Workers exposed to nitroglycerin and dynamite experienced debilitating headaches, referred to as “bang head” headaches, primarily due to skin absorption.
In 1878, British physician William Murrell took note of these intriguing phenomena and embarked on a novel medical experiment. He administered diluted preparations of nitroglycerin to patients with hypertension and angina, leading to promising results. The outcomes of his tests were published in the esteemed medical journal The Lancet in 1879, sparking interest and curiosity within the medical community.
The use of nitroglycerin as a treatment for various forms of heart disease gained traction in the decades that followed. Notably, even Alfred Nobel, the inventor of dynamite, used nitroglycerin to manage his medical condition before his passing in 1896. He humorously remarked on the twist of fate in being prescribed nitroglycerin, which was often referred to as “Trinitrin” to avoid alarming the public and chemists.
Modern Applications of Nitroglycerin in Heart Health
Today, nitroglycerin remains a cornerstone in the management of heart-related conditions. Patients with angina receive nitroglycerin through various delivery methods, such as injections, pills, sublingual sprays, or transdermal patches. To ensure safety, the active ingredient is consistently diluted to a concentration of 1%. This meticulous process safeguards against the explosive potential of pure nitroglycerin while harnessing its vasodilatory properties to provide relief to those in need.
While nitroglycerin’s efficacy in alleviating chest pain and improving blood flow has been established through over a century of clinical experience, the precise mechanism of action remained a mystery for many years. In the late 19th century, medical professionals often attributed angina to elevated blood pressure. However, William Murrell’s groundbreaking experiments challenged this prevailing belief.
Murrell’s research demonstrated that nitroglycerin could effectively relieve chest pain, even in patients with normal blood pressure. This pivotal observation led to a paradigm shift in understanding the root cause of angina. Rather than high blood pressure, narrowed blood vessels were identified as the primary culprits, and nitroglycerin’s profound effect on vasodilation—relaxing and expanding arteries—emerged as the cornerstone of its therapeutic success.
Interestingly, Frederick Guthrie, an English chemist, had noted a similar vasodilatory effect when working with a chemical known as Amyl Nitrite in 1859. Inhalation of Amyl Nitrite induced physiological changes that mirrored those observed with nitroglycerin. This parallel discovery provided further evidence for the mechanism of vasodilation as a crucial aspect of nitroglycerin’s efficacy.
This volatile substance, born from accidental discovery and harnessed for destructive purposes, ultimately found its place in the world of medicine, offering relief to countless individuals suffering from heart-related conditions. Nitroglycerin’s legacy serves as a testament to human ingenuity, reminding us that even the most unconventional beginnings can lead to transformative advancements that touch and improve lives across the globe.
