Herman Pines – He revolutionized the general understanding of catalysis

Her­man Pines

Her­man Pines

Herman Pines was born in Lodz, Poland, in 1902. After earning his degree at the École Supérieure de Chimie in Lyon, France, he came to the U.S. in 1928. He was the closest associate of Vladimir Nikolayevitch Ipatieff from the day they met in 1930, until Ipatieff’s death in 1952. Ipatieff, who was 35 years older than Pines, then held two jobs: he was an employee of Universal Oil Products (UOP) in Des Plaines and a research professor at Northwestern University. As a consequence of the close interaction of these two devoted scientists, Herman Pines, an employee at UOP, became involved in Ipatieff’s research at Northwestern. What started spontaneously and unofficially, was formalized in 1941, when Herman was appointed Research Assistant Professor at Northwestern, with the stipulation that he should spend his Wednesdays working here. This appointment coincided with the relocation of Ipatieff’s lab from the basement of University Hall to the newly erected Technological Institute.

One of the first actions of this new professor was to write, with Ipatieff, a memorandum to the Chemistry Department proposing the creation of a Catalysis Teaching and High Pressure Laboratory. This document was dated September 29, 1941, but it was not until 1947 that the Catalysis Lab officially opened in the Technological Institute. A special High Pressure Laboratory was built in 1952 and officially dedicated August 14, 1953, in the presence of the Presidents of Northwestern University and of UOP. Professor Sir Hugh Taylor of Princeton University gave a lecture on catalysis for the occasion. Shortly thereafter, a bronze plaque honoring Vladimir N. Ipatieff was mounted over the entrance of the High Pressure Lab; it is now located in the reception area of the Catalysis Center.

Meanwhile, Herman Pines had been promoted, in 1951, to the rank of Associate Research Professor; after Ipatieff’s death, in 1952, he became the first V.N. Ipatieff Professor of Organic Chemistry. On January 1, 1953, he left UOP and began officially as a full-time professor at Northwestern.

Only a few of the outstanding scientific achievements of Herman Pines can be mentioned here; it is not an overstatement to say that his work revolutionized the general understanding of chemistry, in particular the chemistry of hydrocarbons interacting with strong acids.

An unchallenged dogma of the chemistry of the 1930’s was that paraffins would not react with anything at low temperature; even the name of this class of compounds, “parum affinis,” was based on this assumed lack of reactivity. It must have been quite a shock to the scientists of those days, when Pines and Ipatieff showed, in 1932, that in the presence of a strong acid the paraffin iso-butane would react, even at -35 ºC, with olefins. This was the basis of the alkylation process, patented in 1938 and industrially developed soon after. Its most spectacular application is the synthesis of iso-octane from n-butene and iso-butane. Iso-octane improves the quality of gasoline and airplane fuel; it played a decisive role in the victory of the Royal Air Force during the Battle of Britain in 1941. The catalysis of converting paraffins to isoparaffins is, of course, one of the cornerstone of the petroleum industry.

The alkylation process was not discovered by accident. It was the pinnacle of research that started with an observation that puzzled Herman Pines in 1930. At that time he was working in the analytical lab of UOP; his task was to vigorously shake petroleum fractions with concentrated sulfuric acid in a calibrated glass cylinder and to determine how much of the oil dissolved in the aqueous acid phase. It was known that only unsaturated hydrocarbons would be dissolved in the acid; this experiment of shaking the petroleum and reading the meniscus was the standard procedure to determine how many unsaturated products were present in a petroleum fraction. Herman observed, however, that after a few hours the phase boundary between oil and acid had shifted again: more oil was formed-oil that would not dissolve in the aqueous phase. Apparently paraffins had been formed from olefins; Herman concluded that this process required the simultaneous formation of a highly unsaturated coproduct which remained dissolved in the aqueous phase. They called this process “conjunct polymerization,” and years later analytical methods were found which permitted identification of this unsaturated coproduct as a mixture of substituted cyclopentadienes. The step which led from this early observation to the alkylation process was later described by Herman:

“On a hunch we thought that paraffins might even react with olefins in the presence of acids; we therefore introduced a stream of ethylene and hydrogen chloride to a stirred mixture of the pentanes and AlCl3. We observed that the ethylene was absorbed and that the hydrocarbons recovered from the reaction consisted of saturated hydrocarbons only, an indication that ethylene must have reacted with the pentanes.”

On this basis, Herman Pines and Vladimir Ipatieff developed the new chemistry of acid catalyzed reactions; it formed the cornerstone of their scientific work and was brought to its present beauty by Herman in his years at Northwestern. Major discoveries led to new processes for the isomerization of paraffins and the alkylation of aromatic compounds, but also to base catalyzed organic reactions. Two hundred and fifty publications in the scientific literature, one hundred and forty-five U.S. patents and the book “The Chemistry of Catalytic Hydrocarbon Conversions” demonstrate the wealth of Herman’s scientific legacy. The forty-one graduate students and thirty-three postdoctoral fellows who performed research in his lab helped carry his scientific message to the world. As U.S. editor of Advances in Catalysis, he keenly looked for and critically evaluated new concepts of catalysis, and assured that their originators described them carefully to the scientific community. In 1957 he was chairman of the Chicago Catalysis Society, in 1960 chairman of the Gordon Conference of Catalysis. He received three awards from the ACS, an honorary degree from the University of Lyon and invitations to lecture and advise in Israel, Brazil, Venezuela, Argentina, Poland, Czechoslovakia and Spain.

The Catalysis Center remained his scientific home. He rarely missed a seminar and often asked critical questions. He could be quite sharp when speakers used catalysis only as a buzzword for the introduction of their lectures and spoke about work of rather questionable relevance to “real” catalysis. Although he could be critical, he was never insensitive; his gentle and friendly nature made it quite impossible for him to do any harm to anyone. While there is a unanimous consensus that he was one of the towering scientists of this century, he always remained very modest; when his trendsetting discoveries of the 1930’s were mentioned, he always referred them to Ipatieff. He worked assiduously his entire life, bringing his last book to completion at the age of ninety. Future generations can learn from his example how revolutionary discoveries arise from sharp observations by an investigating mind. Herman Pines passed away on April 10, 1996.
Contributed by Wolfgang Sachtler