Wallace Hume Carothers (; April 27, 1896 – April 29, 1937) was an American chemist, inventor and the leader of
organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...
at
DuPont
DuPont de Nemours, Inc., commonly shortened to DuPont, is an American multinational chemical company first formed in 1802 by French-American chemist and industrialist Éleuthère Irénée du Pont de Nemours. The company played a major role in ...
, who was credited with the invention of
nylon
Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic.
Nylon is a silk-like thermoplastic, generally made from petro ...
.
Carothers was a group leader at the
DuPont Experimental Station
The DuPont Experimental Station is the largest research and development facility of DuPont. Located on the banks of the Brandywine Creek in Wilmington, Delaware, it is home to some of the most important discoveries of the modern chemical indus ...
laboratory, near
Wilmington, Delaware
Wilmington ( Lenape: ''Paxahakink /'' ''Pakehakink)'' is the largest city in the U.S. state of Delaware. The city was built on the site of Fort Christina, the first Swedish settlement in North America. It lies at the confluence of the Christina ...
, where most
polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
research was done. Carothers was an organic chemist who, in addition to first developing nylon, also helped lay the groundwork for
neoprene
Neoprene (also polychloroprene) is a family of synthetic rubbers that are produced by polymerization of chloroprene.Werner Obrecht, Jean-Pierre Lambert, Michael Happ, Christiane Oppenheimer-Stix, John Dunn and Ralf Krüger "Rubber, 4. Emulsion R ...
. After receiving his Ph.D., he taught at several universities before he was hired by DuPont to work on fundamental research.
He married Helen Sweetman on February 21, 1936. Carothers had been troubled by periods of depression since his youth. Despite his success with nylon, he felt that he had not accomplished much and had run out of ideas. His unhappiness was exacerbated by the death of his sister, and on April 28, 1937, he committed suicide by drinking
potassium cyanide
Potassium cyanide is a compound with the formula KCN. This colorless crystalline salt, similar in appearance to sugar, is highly soluble in water. Most KCN is used in gold mining, organic synthesis, and electroplating. Smaller applications includ ...
. His daughter, Jane, was born on November 27, 1937.
Education and academic career
Carothers was born on April 27, 1896, in
Burlington, Iowa
Burlington is a city in, and the county seat of, Des Moines County, Iowa, United States. The population was 23,982 in the 2020 census, a decline from the 26,839 population in 2000. Burlington is the center of a micropolitan area, which includes ...
, to Ira and Mary Evalina Carothers. He was the oldest of four children. He had one brother and two sisters: John, Isobel and Elizabeth. As a youth, Carothers was fascinated by tools and mechanical devices and spent many hours experimenting. He attended public school in
Des Moines, Iowa
Des Moines () is the capital and the most populous city in the U.S. state of Iowa. It is also the county seat of Polk County. A small part of the city extends into Warren County. It was incorporated on September 22, 1851, as Fort Des Moines, ...
, where he was known as a conscientious student. After graduation, and under pressure from his father, Carothers enrolled in the Capital City Commercial College in Des Moines, where his father was vice-president, completing the accountancy and secretarial curriculum in July 1915.
In September 1915, he entered
Tarkio College
Tarkio College was a college that operated in Tarkio, Missouri, from 1883 to 1992. The institution was supported by the United Presbyterian Church in the United States of America, followed by the Presbyterian Church (USA).
It was closed after ...
in
Missouri
Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...
. Although he initially majored in English, he switched to chemistry under the influence of Arthur Pardee, head of that department. Carothers so excelled in chemistry that before graduation he was made a chemistry instructor and studied for as well as taught the senior course when Pardee left to become chairman of the chemistry department at the
University of South Dakota
The University of South Dakota (USD) is a public research university in Vermillion, South Dakota. Established by the Dakota Territory legislature in 1862, 27 years before the establishment of the state of South Dakota, USD is the flagship univ ...
. He graduated from Tarkio in 1920 at the age of 24 with a bachelor of science degree. Then he went to the
University of Illinois
The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the University ...
for his master of arts degree, which he received in 1921 under the guidance of Professor
Carl Marvel.
During the 1921–22 school year, Carothers held a one-year appointment as a chemistry instructor at the
University of South Dakota
The University of South Dakota (USD) is a public research university in Vermillion, South Dakota. Established by the Dakota Territory legislature in 1862, 27 years before the establishment of the state of South Dakota, USD is the flagship univ ...
. It was at the University of South Dakota that he began his independent research that resulted in an article accepted by the ''
Journal of the American Chemical Society
The ''Journal of the American Chemical Society'' is a weekly peer-reviewed scientific journal that was established in 1879 by the American Chemical Society. The journal has absorbed two other publications in its history, the ''Journal of Analytical ...
''. In this paper he measured physical properties of
phenyl isocyanate
Phenyl isocyanate is an organic compound typically abbreviated PhNCO. The molecule consists of a phenyl ring attached to the isocyanate functional group. It is a colourless liquid that reacts with water. Phenyl isocyanate has a strong odor and te ...
and of diazobenzene-imide (now known as
phenyl azide
Phenyl azide is an organic compound with the formula C6H5N3. It is one of the prototypical organic azides. It is a pale yellow oily liquid with a pungent odor. The structure consists of a linear organic azide, azide substituent bound to a phenyl ...
). The properties have very similar values, which led him to the conclusion that the structure of the second compound is C
6H
5-N=N=N, with the three nitrogen atoms in a linear chain rather than a ring as previously thought.
He went back to the University of Illinois to study for his Ph.D. under
Roger Adams
Roger Adams (January 2, 1889 – July 6, 1971) was an American organic chemist who developed the eponymous Adams' catalyst, and helped determine the composition of natural substances such as complex vegetable oils and plant alkaloids. He isolat ...
. His degree was awarded in 1924. He specialized in organic chemistry and minored in physical chemistry and mathematics. He worked as a research assistant during 1922–1923 and received the Carr Fellowship for 1923–24. This was the most prestigious award offered by the university at that time.
He was initiated into
Alpha Chi Sigma
Alpha Chi Sigma () is a professional fraternity specializing in the fields of the chemical sciences. It has both collegiate and professional chapters throughout the United States consisting of both men and women and numbering more than 70,000 mem ...
in 1926 as a member of Zeta Chapter at the University of Illinois.
After receiving his Ph.D., Carothers stayed at the University of Illinois for two years as an instructor in organic chemistry.
In 1926, Carothers moved to
Harvard University
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...
. Again he was an instructor in organic chemistry.
James B. Conant
James Bryant Conant (March 26, 1893 – February 11, 1978) was an American chemist, a transformative President of Harvard University, and the first U.S. Ambassador to West Germany. Conant obtained a Ph.D. in Chemistry from Harvard in 1916. ...
, who became President of
Harvard College
Harvard College is the undergraduate college of Harvard University, an Ivy League research university in Cambridge, Massachusetts. Founded in 1636, Harvard College is the original school of Harvard University, the oldest institution of higher lea ...
in 1933, said of Carothers:
In his research, Dr. Carothers showed even at this time the high degree of originality which marked his later work. He was never content to follow the beaten path or to accept the usual interpretations of organic reactions. His first thinking about polymerization
In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer, monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are ...
and the structure of substances of high molecular weight began while he was at Harvard.
In 1927, DuPont decided to fund fundamental, pure research: research not deliberately aimed at the development of a money-making product. Carothers traveled to
Wilmington, Delaware
Wilmington ( Lenape: ''Paxahakink /'' ''Pakehakink)'' is the largest city in the U.S. state of Delaware. The city was built on the site of Fort Christina, the first Swedish settlement in North America. It lies at the confluence of the Christina ...
, to discuss the possibility of being in charge of organic chemistry at the new DuPont laboratory for fundamental research.
Move to DuPont
The decision to leave academia was difficult for Carothers. At first he refused DuPont's offer of employment, explaining that "I suffer from neurotic spells of diminished capacity which might constitute a much more serious handicap there than here." In spite of this admission, a DuPont executive, Hamilton Bradshaw, traveled to Harvard and convinced Carothers to change his mind. His salary was $500 a month as compared with only $267 at Harvard ($3200 per year).
Later in a letter to Wilko Machetanz, his Tarkio roommate, Carothers expanded on his feelings of depression: "I find myself, even now, accepting incalculable benefits proffered out of sheer magnanimity and good will and failing to make even such trivial return as circumstances permit and human feeling and decency demand, out of obtuseness or fear or selfishness or mere indifference and complete lack of feeling."
Neoprene
At Dupont Carothers was given a position in its new fundamental research program that was just recently established in Wilmington, Delaware and the company had allowed him to choose any research of his choice. He chose polymer research because the subject needed theoretic exploration and had immense commercial implications. Carothers began working at the DuPont Experimental Station on February 6, 1928. The synthesis of a
polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
with a
molecular weight
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...
of more than 4,200, the mass achieved by Dr.
Emil Fischer
Hermann Emil Louis Fischer (; 9 October 1852 – 15 July 1919) was a German chemist and 1902 recipient of the Nobel Prize in Chemistry. He discovered the Fischer esterification. He also developed the Fischer projection, a symbolic way of dra ...
, was his primary goal.
By the summer of 1928, Carothers had a small staff of Ph.D. chemists and two consultants: Dr. Roger Adams, his thesis advisor, and Dr. Carl Marvel, his instructor of organic chemistry at the University of Illinois. The laboratory where these top scientists worked became known as "Purity Hall". It was discouraging that by the middle of 1929, "Purity Hall" had not produced a polymer with a weight of much over 4,000.
In January 1930, Dr.
Elmer K. Bolton became assistant chemical director in the chemical department, and thus, Carothers' immediate boss. Bolton wanted practical results in 1930, and his wish was fulfilled. Bolton asked Carothers to examine the chemistry of an
acetylene
Acetylene (systematic name: ethyne) is the chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure ...
polymer with the goal of creating synthetic
rubber
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and ...
. In April 1930, one of Carothers' staff, Dr.
Arnold M. Collins Arnold Miller Collins (1899-1982) was a chemist at DuPont who, working under Elmer Bolton and Wallace Carothers, first isolated polychloroprene and 2-chloro-1, 3-butadiene in 1930.
Personal
Born 1899. Married Helen Clark Collins. Died October ...
, isolated
chloroprene
Chloroprene is the common name for 2-chlorobuta-1,3-diene (IUPAC name) with the chemical formula CH2=CCl−CH=CH2. Chloroprene is a colorless volatile liquid, almost exclusively used as a monomer for the production of the polymer polychloroprene, ...
, a liquid which polymerized to produce a solid material that resembled rubber. This product was the first synthetic rubber and is known today as
Neoprene
Neoprene (also polychloroprene) is a family of synthetic rubbers that are produced by polymerization of chloroprene.Werner Obrecht, Jean-Pierre Lambert, Michael Happ, Christiane Oppenheimer-Stix, John Dunn and Ralf Krüger "Rubber, 4. Emulsion R ...
.
Polyesters
In the same year, Dr.
Julian W. Hill, another member of the Carothers team, began work again on attempting to produce a
polyester
Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natural ...
with a molecular weight of above 4,000. His efforts were soon met with great success when he produced a synthetic polymer with a molecular weight of about 12,000. The high molecular weight allowed the melted polymer to be stretched out into strings of fiber. Thus was created the first synthetic
silk
Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the coc ...
, described by the chemists as a superpolyester.
Polyesters and polyamides are examples of
condensation polymers formed by
step-growth polymerization
Step-growth polymerization refers to a type of polymerization mechanism in which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers. Many naturally occurring a ...
. Carothers worked out the theory of step-growth polymerization and derived the
Carothers equation which relates the average
degree of polymerization
The degree of polymerization, or DP, is the number of monomeric units in a macromolecule or polymer or oligomer molecule.
For a homopolymer, there is only one type of monomeric unit and the ''number-average'' degree of polymerization is given by ...
to the fractional conversion (or
yield) of monomer into polymer. This equation shows that for a high molecular weight, a very high fractional conversion is needed (for step-growth polymers only).
Hill also produced a synthetic fiber that was elastic and strong by combining
glycols
A diol is a chemical compound containing two hydroxyl groups ( groups). An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified.
The most common industrial diol is e ...
and diacids and heating under reduced pressure, using a
molecular still to remove the last traces of water produced in the condensation reaction. Unfortunately, the fiber produced could not be commercialized because it reverted to a sticky mass when placed in hot water. Carothers dropped his research on polymers for several years.
Later career and depression
In 1931, Carothers moved into a house in Wilmington, which became known as Whiskey Acres, with three other DuPont scientists. He was no recluse, but his depressive moods often prevented him from enjoying all the activities in which his roommates took part. In a letter to a close friend, Frances Spencer, he said, "There doesn't seem to be much to report concerning my experiences outside of chemistry. I'm living out in the country now with three other bachelors, and they being socially inclined have all gone out in tall hats and white ties, while I after my ancient custom sit sullenly at home." At about this time, Carothers showed Julian Hill that he kept a capsule of cyanide attached to his watch chain.
Carothers hated the public speaking that was necessary to maintain his high-profile. In a letter to Frances Spencer in January 1932, he related, "I did go up to New Haven during the holidays and made a speech at the organic symposium. It was pretty well received but the prospect of having to make it ruined the preceding weeks and it was necessary to resort to considerable amounts of alcohol to quiet my nerves for the occasion. … My nervousness, moroseness and vacillation get worse as time goes on, and the frequent resort to drinking doesn't bring about any permanent improvement. 1932 looks pretty black to me just now."
In 1932, the agreement under which Carothers was hired was modified by Dr. Bolton. "Purity Hall" would now focus on "effecting a closer relationship between the ultimate objectives of our work and the interests of the company". This meant that funds were shifted from pure research to practical research. Carothers did not see himself as a skilled commercial researcher. He proposed that fundamental work be limited to two or three proposals, which would be consistent with DuPont's interests.
Carothers' personal life during this time was busy. He was having an affair with a married woman, Sylvia Moore, who with her husband filed for divorce in 1933. Concomitantly he worried about the financial problems of his parents and planned to bring them to Wilmington. With no thought of the possible emotional ramifications of this move, he bought a house in Arden about from the Experimental Station and moved into it with his parents. He was 37 at the time. Interactions with his parents soon became tense. Carothers was still seeing Sylvia Moore, who was now single, and his parents greatly disapproved of the relationship. Finding the tension in the household too wearing, his parents returned to Des Moines in the spring of 1934.
Polyamides
In 1934, Carothers turned his attention to fibers again. Now the team substituted di
amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituen ...
s for glycols to produce a type of polymer called a
polyamide
A polyamide is a polymer with repeating units linked by amide bonds.
Polyamides occur both naturally and artificially. Examples of naturally occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made through ...
. These substances were much more stable than the polyesters formed by using the glycols. The ability of polyamides to form crystalline domains through hydrogen bonding gives them increased mechanical properties. Therefore, they might produce a synthetic silk that would be practical for everyday use. His research resulted in the invention of a number of new polyamides. The lab work for this project was conducted by Dr. W. R. Peterson and Dr. Donald Coffman. In 1935, Dr. Gerard Berchet was assigned to this polyamide research.
It was during this productive period of research, in the summer of 1934, before the eventual invention of nylon, that Carothers disappeared. He did not come into work, and no one knew where he was. He was found in a small psychiatric clinic, Pinel Clinic, near the famous
Phipps Clinic associated with
Johns Hopkins Hospital
The Johns Hopkins Hospital (JHH) is the teaching hospital and biomedical research facility of the Johns Hopkins School of Medicine, located in Baltimore, Maryland, U.S. It was founded in 1889 using money from a bequest of over $7 million (1873 mo ...
in Baltimore. Apparently, he had become so depressed that he drove to Baltimore to consult a psychiatrist, who put him in the clinic.
Nylon
Shortly after his release from the clinic, Carothers returned to DuPont. Bolton instructed Carothers to work on polyamides.
Carother's work in linear super-polymers began as an unrestricted foray into the unknown, with no practical objective in mind. But the research was in a new field in chemistry and
Du Pont believed that any new chemical breakthrough would likely be of value to the company. In the course of research, Carothers obtained some super-polymers that became viscous solids at high temperatures, and the observation was made that filaments could be made from this material if a rod was dipped in the molten polymer and withdrawn. At this discovery, the focus of the project shifted to these filaments and 'Nylon' was the result.
On February 28, 1935, Gerard Berchet, under the direction of Carothers, produced a half-ounce of polymer from
hexamethylenediamine
Hexamethylenediamine is the organic compound with the formula H2N(CH2)6NH2. The molecule is a diamine, consisting of a hexamethylene hydrocarbon chain terminated with amine functional groups. The colorless solid (yellowish for some commercial sam ...
and
adipic acid
Adipic acid or hexanedioic acid is the organic compound with the formula (CH2)4(COOH)2. From an industrial perspective, it is the most important dicarboxylic acid: about 2.5 billion kilograms of this white crystalline powder are produced annuall ...
, creating polyamide 6-6, the substance that would come to be known as Nylon. It was difficult to work with because of its high melting point, but Bolton chose this polyamide as the one to develop commercially. He selected Dr. George Graves to work with Carothers on the project. Eventually, Graves supplanted Carothers as the leader of the polyamide project. In addition, dozens of chemists and engineers worked on refining polyamide 6-6 into a viable commercial product.
Marriage and death
On February 21, 1936, Carothers married Helen Sweetman, whom he had been dating since 1934. Sweetman had a bachelor's degree with a major in chemistry and worked for DuPont on the preparation of patent applications. During his lifetime, his friends would often judge his marriage with Helen in comparison to his previous affair with Sylvia Moore, stating that they thought Moore was a greater woman.
Soon afterwards, on April 30, 1936, Carothers became the first industrial organic chemist to be elected to the
National Academy of Sciences
The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nati ...
, a very high honor. Yet by June 1936, in spite of this honor which validated his contributions to science, Carothers could not shake the depression that prevented him from working. In early June, he was involuntarily admitted to the Philadelphia
Institute of the Pennsylvania Hospital
The Institute of Pennsylvania Hospital, also known as Kirkbride's Hospital or the Pennsylvania Hospital for Mental and Nervous Diseases, was a psychiatric hospital located at 48th and Haverford Streets in Philadelphia, Pennsylvania, USA. It oper ...
, a prestigious mental hospital, under the care of psychiatrist Dr. Kenneth Appel. One month later, he was given permission to leave the institute to go hiking in the Tyrolean Alps with friends. The plan was for him to day hike with Dr. Roger Adams and Dr. John Flack for two weeks. After they left, he continued hiking by himself, without sending word to anyone, not even his wife. On September 14, he suddenly appeared at her desk at the Experimental Station. From that point on Carothers was not expected to perform any real work at the Experimental Station. He would often go in and visit. He began living in Whiskey Acres again, after his wife had agreed with Dr. Appel that she was not strong enough to watch over Carothers.
On January 8, 1937, Carothers' sister Isobel died of pneumonia. Wallace and Helen Carothers traveled to Chicago to attend her funeral and then to Des Moines for her burial. He still traveled to Philadelphia to visit his psychiatrist, Dr. Appel, who told a friend of Carothers that he thought suicide was the likely outcome of Carothers' case.
On April 28, 1937, Carothers went to the Experimental Station to work. About 5pm the next day, he was found dead in his hotel room with a squeezed lemon and some cyanide salt nearby. No note was found.
[Hermes, ''Enough for One Lifetime'' p.291, which cites the ''Wilmington Morning News'' and the ''New York Times'' of April 30, 1937]
He was posthumously inducted into the
Alpha Chi Sigma
Alpha Chi Sigma () is a professional fraternity specializing in the fields of the chemical sciences. It has both collegiate and professional chapters throughout the United States consisting of both men and women and numbering more than 70,000 mem ...
Hall of Fame in 1982.
Patents
* "Alkylene Carbonate and Process of Making It", filed November 1929, issued March 1935
* "Alkylene Ester of Polybasic Acids", filed August 1929, issued August 1935
* "Linear Condensation Polymers", filed July 1931, issued February 1937
References
External links
*
Encyclopedia of World Biography on Wallace Hume Carothers*
National Academy of Sciences Biographical Memoir
{{DEFAULTSORT:Carothers, Wallace
1896 births
1937 suicides
20th-century American chemists
DuPont people
People from Burlington, Iowa
Polymer scientists and engineers
Suicides by cyanide poisoning
Textile scientists
Suicides in Philadelphia
University of Illinois Urbana-Champaign alumni
Harvard University faculty
Members of the United States National Academy of Sciences
20th-century American inventors
20th-century agronomists