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00:00:34 I'm Leon Gortler from Brooklyn College at the City University of New York,

00:00:37 and it's my pleasure today to be talking with Mr. Louis Hammett,

00:00:41 who is one of the real founding fathers of physical organic chemistry.

00:00:45 I've been working on the history of physical organic chemistry for a few years,

00:00:50 and Professor Hammett and I have talked a number of times before this.

00:00:56 Professor Hammett has had a long and very distinguished career.

00:01:02 He's won almost every conceivable medal given for chemists and for scientists in the country.

00:01:09 Some of the medals that he's been awarded are the Lewis Medal, the Priestley Medal,

00:01:14 the Nichols Award, the Gibbs Medal.

00:01:16 He's also received the Barnard Medal for Meritorious Service to Science

00:01:20 and the Columbia Graduate Alumni Medal.

00:01:24 And in 1967, he was given the National Medal of Science by Lyndon Johnson.

00:01:30 Louie, I know you were born in Wilmington, Delaware,

00:01:34 a most appropriate place for an outstanding chemist to be born.

00:01:39 And we just realized that in a few weeks it will be 88 years ago that you were born.

00:01:46 But you spent very little time in Wilmington and actually grew up in Portland, Maine.

00:01:51 And I'd like you to tell me a little bit about growing up in Maine

00:01:58 and actually the major people and the books and the courses that influenced you

00:02:03 and prompted you to take up the life of a scientist.

00:02:07 Well, it's a little hard to say.

00:02:09 My father was a mechanical engineer, and I had an uncle who lived in our house for a time

00:02:17 who was an architect.

00:02:19 And between them, I had a good deal of background in technical things.

00:02:25 I had a woodturning lathe that I played with and things like that.

00:02:30 And then I had a high school course that I guess was a pretty good course,

00:02:36 although it was taught by a man who'd been hired as a basketball coach.

00:02:42 And I had to be a little tolerant after I'd read the book

00:02:45 and correcting him about uncertainties in his own analysis of the situation.

00:02:54 I can't say that did very much to me, but I wanted to go to Harvard.

00:02:58 My father had gone to Harvard, and so I went there in 1912.

00:03:05 I had a good undergraduate course, although by present standards, of course,

00:03:10 it was pretty old-fashioned.

00:03:12 Actually, the chemistry staff in the university had just been pretty much reorganized,

00:03:22 and they were very excited about the Arrhenius-Ostwald-Nernst theories

00:03:30 of electrolyte solutions.

00:03:33 I remember being bored because I got the same thing repeated over and over again,

00:03:37 one course after another.

00:03:38 I'm sure I had it all three times each time in blissful ignorance of the fact

00:03:43 that I'd previously had it from another professor earlier.

00:03:49 But I did learn several things.

00:03:57 Particularly, I did learn the techniques of accurate quantitative analysis,

00:04:05 which has stood me good stead all my life.

00:04:09 And I was very much inspired by the lectures of Elmer Kohler,

00:04:16 who was the kind of organic chemist who was interested in the theory of organic chemistry

00:04:24 and not so much in its practical applications.

00:04:27 He talked a great deal about principles.

00:04:32 I think there were some limitations in what I learned from him, time limitations.

00:04:39 For instance, I never learned anything about terpenes there

00:04:43 because the course ended before he got to them.

00:04:47 But one of the severe limitations was that that was a period,

00:04:52 a sort of a blackout in chemical theory.

00:04:56 Nobody thought that there was anything to be learned from reaction rate measurements.

00:05:03 There wasn't anything about reaction rates in Kohler's lectures.

00:05:07 And when I went to Zurich later and read the Henry Theorian book,

00:05:15 which was the Bible of theoretical organic chemists,

00:05:18 there wasn't a mention of reaction rates in that whole book.

00:05:23 But between Kohler and Scheer and Staudinger's laboratory at Zurich,

00:05:32 I really got pretty well trained in the techniques of organic chemical activities.

00:05:42 And I came out, on the whole, sort of dissatisfied

00:05:49 because while people talked about theories and about principles,

00:05:55 they didn't get very far in analyzing it.

00:06:05 And it was only really later on that I became interested

00:06:10 in the kind of techniques that were so effective

00:06:15 in setting up a basic theory of organic chemical principles.

00:06:22 But I still learned a good deal out of both of those.

00:06:25 You mentioned going to Zurich,

00:06:28 and I know you won the Sheldon Traveling Fellowship

00:06:31 when you graduated from Harvard, and that permitted you to go.

00:06:34 That's right.

00:06:35 And how did you happen to choose Zurich?

00:06:37 Well, I consulted with various members of the staff,

00:06:41 and I talked to Richards,

00:06:44 and he thought that because of the war,

00:06:51 which was then on in 1916, although we weren't in it,

00:06:56 he didn't think there were any very good physical chemists

00:06:59 anywhere in Europe where I could get to.

00:07:01 And then I talked to Kohler, and Kohler suggested Staudinger,

00:07:04 who was in a little country,

00:07:06 although Staudinger was a German nationalist, national.

00:07:10 So I went to Zurich.

00:07:14 Lewis, I mean, not Lewis, but the physical chemist

00:07:21 had suggested G. N. Lewis in this country,

00:07:24 but I wanted to go to Europe.

00:07:26 I wanted to go abroad.

00:07:28 It was that, I think, more than a choice between materials

00:07:32 that decided me to go to Staudinger.

00:07:36 I wanted to see something out of this country.

00:07:39 Of course, the year came to an end after we were in the war,

00:07:43 and I came back to this country.

00:07:47 And through an old friend of my father's

00:07:52 who was a chemist at the Bureau of Standards,

00:07:54 Dr. Voorhees,

00:07:58 I learned that there were all kinds of activities

00:08:03 involving chemists in war work,

00:08:07 and so I got a job with a group at the Bureau of Standards

00:08:12 which was directed by Hal Beans,

00:08:16 who was a professor at Columbia,

00:08:19 and ran a chemical group there.

00:08:25 And we worked for a while in Washington

00:08:28 at the Bureau of Standards.

00:08:30 Then we moved to Pittsburgh,

00:08:32 and we had a whole laboratory building,

00:08:34 the Pittsburgh Testing Laboratory, I think it was called,

00:08:37 downtown near the railroad station.

00:08:40 And I lived there during most of the rest of the First World War.

00:08:47 And during that period,

00:08:49 I was working mostly on cellulose acetate

00:08:52 and other ester wing dopes.

00:08:57 In those days, they made airplanes out of sticks

00:09:00 and covered them with fabric,

00:09:03 and then they applied some kind of a lacquer wing dope

00:09:11 that, when it dried, shrunk the fabric and gave it a stiff surface.

00:09:15 And they'd gotten worried about nitrocellulose

00:09:18 because of its inflammability,

00:09:20 and they were trying to bring in cellulose acetate.

00:09:23 Cellulose acetate is a more difficult material to handle.

00:09:27 It's more limited solubility,

00:09:30 and we're having a hard time

00:09:32 finding the first place to get the acetate radicals,

00:09:35 and then to find suitable solvents,

00:09:41 particularly high boilers.

00:09:44 So I worked on things of that sort,

00:09:46 and I was head of a laboratory group in that case.

00:09:52 And then the war ended, and I wanted to get married,

00:09:56 and I wanted to get a job that paid reasonably,

00:10:00 and I became the laboratory chemist

00:10:05 for an informal group that worked

00:10:09 in the private laboratory of E.C. Warden

00:10:13 in Maplewood, New Jersey.

00:10:17 And he was associated with Sam Eisenman,

00:10:20 who was a German,

00:10:22 and who'd been in the perfume oil,

00:10:27 perfume component business,

00:10:30 and had a small business in Jersey City,

00:10:33 but also had set up a dye stuff laboratory

00:10:39 in the neighbor, that part of New Jersey,

00:10:41 which we worked with.

00:10:45 And I worked mostly,

00:10:48 I guess I got that job through,

00:10:50 well, to begin with,

00:10:51 because Eisenman had been making cellulose acetate,

00:10:55 and he knew my background in it.

00:10:58 I think it's important that we emphasize the fact

00:11:01 that you had worked in dyes.

00:11:03 I had worked in dyes, mostly in development.

00:11:07 Some of it was making new dyes,

00:11:09 but mostly using published material

00:11:14 on dyes and pharmaceuticals, both dyes.

00:11:18 In fact, I worked in Eisenman's plant,

00:11:21 the perfume constituent plant in Jersey City,

00:11:29 on a sort of a pilot plant operation,

00:11:34 making one of the important pharmaceuticals.

00:11:37 One of the byproducts of that was that

00:11:42 when I'd go into this plant,

00:11:44 I'd take off my outer clothes and hang them up,

00:11:48 but inevitably one got contaminated

00:11:51 with the odor of cheap perfume.

00:11:54 And I had to go back by trolley up to Jersey City

00:11:57 and then by the Lackawanna Railroad back to Milburn,

00:12:00 and I smelled.

00:12:03 I can remember people would come in

00:12:06 and sit down beside me in the railroad train,

00:12:08 take a sniff and get up and move into another car.

00:12:12 Queer expression on their face.

00:12:15 But I survived all of those things,

00:12:17 and I had a lot of good experience

00:12:19 with technical matters involving dyestuffs and pharmaceuticals.

00:12:25 Because I know that the dyestuff work comes back eventually

00:12:28 and contributed to one of your more important contributions.

00:12:32 In 1920, you came to Columbia,

00:12:35 where you remained for the next 41 years.

00:12:38 How did you happen to come to get to Columbia?

00:12:41 Well, I hadn't seen or heard from Beans since the end of the war,

00:12:49 although I'd tried to write to him and never got...

00:12:53 It was sort of typical of him.

00:12:56 He didn't respond.

00:12:58 But I got an invitation to a lecture

00:13:01 that was being given in Havemeyer Hall,

00:13:04 and I took the Lackawanna Railroad and went in.

00:13:09 This was in Havemeyer Hall,

00:13:12 which I lectured for years later on.

00:13:16 And I heard this lecture.

00:13:18 I'd forgotten what the lecture was all about,

00:13:20 and rather typically Hal Beans wasn't down at the lecture,

00:13:23 but rather typically also he was working in his own laboratory upstairs,

00:13:27 and after the lecture I went up and chatted with him.

00:13:33 And I learned that one of the men who'd been with us during the war,

00:13:38 Leonard Eintema,

00:13:40 had just refused an offer of an instructorship at Columbia.

00:13:44 And this was the period just after the war,

00:13:47 and the universities were expanding,

00:13:50 and they were having trouble getting staff,

00:13:53 and they'd offered Eintema a job,

00:13:56 and Eintema had just decided he was going to stay at Illinois

00:13:59 where he was doing graduate work.

00:14:02 And he didn't want to come to Columbia,

00:14:05 and Beans said to me,

00:14:07 Well, I didn't think of you because I knew you were devoted to industrial work.

00:14:12 I said, Well, just invite me, and he did.

00:14:16 So I came into Columbia as a graduate student,

00:14:20 and I proceeded to take a lot of courses,

00:14:24 although I already had this graduate experience in Surrey,

00:14:28 and I had some courses there.

00:14:31 So I was working pretty hard,

00:14:33 and the first year I was mostly taking courses,

00:14:37 and some of them were inconvenient.

00:14:41 There was one chap, James Kendall,

00:14:44 who liked to get his chores over early

00:14:47 and used to insist on giving lectures at 8 o'clock,

00:14:50 and for somebody who lived at 181st Street,

00:14:54 coming down to an 8 o'clock lecture

00:14:56 and getting back after 10 o'clock at night

00:14:59 was kind of a difficulty.

00:15:03 But I survived, and the second year I really got into research.

00:15:08 I worked on the hydrogen electrode,

00:15:11 which I became very much interested in.

00:15:13 Essentially it was my own problem.

00:15:15 You worked with Beans.

00:15:16 I worked technically with Beans.

00:15:18 I had to have a sponsor, but it wasn't his problem, actually.

00:15:21 It was my own.

00:15:23 I'd been playing around with aluminum hydroxide precipitates,

00:15:29 and I discovered essentially that they had the properties of ion exchange resins.

00:15:34 They picked up anything that had been in the solution,

00:15:37 any anions, and that the anions that had been picked up by a fresh precipitate

00:15:42 could be taken out by another anion.

00:15:46 So essentially these were ion exchange resins, really.

00:15:51 This got me into the hydrogen electrode,

00:15:54 which was a pretty brand-new instrument.

00:15:57 I studied the properties of that

00:16:00 and developed a long-term interest in the properties of electrodes,

00:16:05 in which I did research work considerably later on.

00:16:09 But anyway, I finished my research work

00:16:16 and passed my examinations in the fall of 1922.

00:16:22 I technically got my degree in June of 1923.

00:16:27 Meanwhile, I was an instructor as well as a graduate student.

00:16:32 Shortly after I got my degree, I think it was 1924,

00:16:38 I was appointed to assistant professor.

00:16:42 In 1929, I got tenure as an associate professor.

00:16:51 I was very busy.

00:16:57 I was exploring all kinds of things that might lead to interesting developments.

00:17:02 I didn't have any research students until late in the 1920s.

00:17:07 Then I got Dietz, who worked on solutions in formic acid,

00:17:12 almost contemporaneously with Conant and Hall's work on super-acid solutions

00:17:17 in glacial acetic acid.

00:17:21 I think our publication was a little behind theirs,

00:17:24 but we were both working on it more or less at the same time.

00:17:28 Then I put Derip to work, again late in the 1920s.

00:17:34 He did a tremendous piece of work

00:17:37 and started out this whole acidity function program.

00:17:41 Your first major paper on acidity was the 1928 paper called

00:17:46 The Theory of Acidity.

00:17:48 Yes, The Theory of Acidity.

00:17:51 That goes back to my reading,

00:17:54 because here I was teaching qualitative analysis,

00:18:00 which was essentially the theory of electrolyte solutions.

00:18:06 It was the standard Arrhenius-Ostfeld partial ionization of strong electrolytes

00:18:12 and that sort of thing.

00:18:15 Then I began to read people like Hodge,

00:18:19 who had a profound influence on me,

00:18:22 because he did work in non-aqueous solutions

00:18:26 and studied acids and bases in such systems.

00:18:31 I also had been reading the papers by Brunstad and Copenhagen

00:18:39 and the papers by G. N. Lewis,

00:18:45 who attacked problems of electrolyte solutions

00:18:51 from the point of view of exact thermodynamics

00:18:54 rather than from the point of view of the rough approximations

00:18:58 that Nernst had introduced.

00:19:02 So this was all very stimulating, very exciting.

00:19:07 I always like to point out that

00:19:10 one can learn things from a great scientist

00:19:15 without doing post-doctoral work under his direction,

00:19:18 because I didn't know any of those people at that time.

00:19:22 I just read what they published.

00:19:24 And they did inspire me, and it was a real ferment.

00:19:28 I developed many of these ideas,

00:19:31 including the possibility of a step-by-step use of indicators,

00:19:35 which was the key to this acidity function.

00:19:39 In fact, I think it was Derep who thought of the term acidity function,

00:19:43 and then the symbol H0.

00:19:47 I think actually we have the acidity function formulas here,

00:19:52 the definition that you had first written of H0,

00:19:56 and then sort of the working definition,

00:19:59 the way you went about the work using the indicators.

00:20:02 And you notice that there are symbols A and F,

00:20:06 activity and activity coefficient,

00:20:09 that had been introduced fairly recently, I think by Lewis.

00:20:13 I see.

00:20:15 I remember someplace you were telling me

00:20:18 that you really worked at the thermodynamics.

00:20:21 I had. I was a serious study.

00:20:23 And of course, in the early 20s,

00:20:26 this was quite an exciting time in chemistry.

00:20:29 Lewis's thermodynamics came out then,

00:20:32 and Lewis's paired electron theory came out then,

00:20:36 and I read everything of that sort.

00:20:39 I could get my hands on it.

00:20:42 You were obviously making good use of it.

00:20:45 Here, in fact, I have a picture

00:20:48 of sort of the major result of the acidity function,

00:20:52 that is, the fact that the acidity of the solution,

00:20:56 or its, I guess, proton-donating ability,

00:20:59 as you call it, goes up significantly.

00:21:02 This is for the whole range from 0% sulfuric acid

00:21:06 to 100% sulfuric acid.

00:21:09 And there's also plotted the logarithm

00:21:12 of the concentration of hydrogen ion,

00:21:15 which goes up and comes to more or less a maximum.

00:21:18 Whereas the actual acidity, in terms of indicators,

00:21:22 in terms of the number of reaction rate phenomena,

00:21:26 goes up almost astronomically.

00:21:29 Yes. I think the last 10% or so,

00:21:32 the increase is about 1,000-fold,

00:21:35 just for a 10% increase in concentration.

00:21:38 That was significant, we thought,

00:21:41 because people had talked about sulfuric acid

00:21:44 as a dehydrating agent, whereas it really was

00:21:47 just a very strong acid, a very strong proton-donator.

00:21:50 In 2002, just before you got to the acidic function,

00:21:53 you published your first book.

00:21:56 Yes, Solutions of Electrolytes.

00:21:59 Incidentally, there's a textbook for the qualitative analysis course,

00:22:03 but my publishers wouldn't let me call it qualitative analysis.

00:22:07 Oh, really?

00:22:09 I had to invent the name Solutions of Electrolytes.

00:22:13 Well, I think it's sort of indicative

00:22:16 of the broad range of things that you went through.

00:22:19 You first published a book in qualitative analysis.

00:22:22 That's right, and it introduced the idea

00:22:25 of complete ionization of strong electrolytes,

00:22:28 which was a brand-new idea in those days,

00:22:31 and becoming current.

00:22:34 We've already talked about what prompted you

00:22:37 to study the acidity in strong acids,

00:22:40 and I have a quote from the second edition

00:22:43 of the Physical Organic Chemistry text,

00:22:46 which says,

00:22:49 and then you said it was the limitations of these tools,

00:22:52 not any deliberate choice,

00:22:55 that led us to the selection of indicators,

00:22:58 most of which were primary nitroanilines.

00:23:01 I assume that goes back to some of your dye work as well.

00:23:04 Then you went on to say,

00:23:07 we now know that this was fortunate,

00:23:10 that if we had had a wider choice, we might have been bewildered.

00:23:13 Well, later on we learned that it depended

00:23:16 on what kind of base one used,

00:23:19 what kind of an acidity function one got.

00:23:22 That I didn't really learn until after I'd retired

00:23:25 and was doing consulting work

00:23:28 at carbide research laboratories

00:23:31 in the 1960s.

00:23:34 That was an eye-opener.

00:23:37 But there are a lot of other kinds of bases

00:23:40 that behave differently as you go up to strong acids,

00:23:43 mostly, I think,

00:23:46 because there are different degrees of solvation,

00:23:49 either of the base or of the conjugate acid.

00:23:55 Then in 1933,

00:23:58 you published a paper with Helmuth Pflueger.

00:24:01 It happens to be one of my favorite Hamlet papers,

00:24:04 and I'd like you to talk a little bit

00:24:08 about the ideas that were there.

00:24:11 Well, as I say, I'd been reading Bernstein,

00:24:14 and Bernstein had discovered

00:24:17 that you could get a logarithmic plot

00:24:20 if you plotted the logarithm of the equilibrium

00:24:23 or rate constants

00:24:31 of a series of acids

00:24:38 that, again, for instance,

00:24:41 if you took the rate constant

00:24:44 for a series of acids

00:24:47 and compared the acid-catalyzed reaction

00:24:50 and compared it with the logarithm

00:24:53 of the ionization constant of the acid,

00:24:56 one got linear plots,

00:24:59 which essentially we realized

00:25:02 were linear relations in free energy.

00:25:05 That was in the background,

00:25:08 and I had become interested

00:25:11 in mechanisms of organic reactions.

00:25:14 One of the great problems

00:25:17 in classical organic theory

00:25:20 was where the break came

00:25:23 when an ester hydrolyzed.

00:25:26 Did the break come on the alkyl

00:25:29 or the acyl side of the ether oxygen?

00:25:32 If it came on one side,

00:25:35 then the logarithm of the rate

00:25:38 for the hydrolysis of the ester

00:25:41 acid-catalyzed hydrolysis

00:25:44 plotted against the logarithm

00:25:47 of the ionization constant

00:25:50 of the corresponding acid

00:25:53 should be linear.

00:25:56 If it came on the other side,

00:26:00 although it didn't work

00:26:03 for orthosubstituted...

00:26:06 Here's one of the first things

00:26:09 that appeared.

00:26:12 This is the alkylation

00:26:15 of trimethylamine

00:26:18 with various methyl esters

00:26:21 of benzoic acids.

00:26:24 Actually, a whole series of acids.

00:26:28 I'm sorry I was talking

00:26:31 about acid-catalyzed reactions,

00:26:34 but what I tried here

00:26:37 was the methylation of the ester.

00:26:40 Here's where you had

00:26:43 alkyl oxygen cleavage,

00:26:46 and you did get linearity.

00:26:49 But these orthosubstituted

00:26:52 benzoic acids didn't fall

00:26:56 within structural limitations.

00:26:59 It didn't work for these

00:27:02 orthosubstituted benzoics.

00:27:05 Then the next one you tried

00:27:08 were the base hydrolysis

00:27:11 of the esters,

00:27:14 where it was acyl oxygen cleavage.

00:27:17 Yes, that was a catalyzed

00:27:20 benzoic acid.

00:27:23 That was a catalyzed hydrolysis

00:27:26 of these esters.

00:27:29 Here were the...

00:27:32 plotted against the ionization

00:27:35 constants of the corresponding acid.

00:27:38 The ones that didn't lie on the line.

00:27:41 On one side were aliphatic esters,

00:27:44 and on the other side

00:27:47 were orthosubstituted benzoic esters.

00:27:50 Although a limited one.

00:27:53 This is sort of the beginning of your work.

00:27:56 This led up to the so-called

00:27:59 Hammett equation.

00:28:02 In that paper as well,

00:28:05 you also discussed

00:28:08 some other solvolysis reactions.

00:28:11 Yes.

00:28:14 That whole period from 1930 to 1940

00:28:18 was a very lively, exciting time

00:28:21 in my laboratory.

00:28:24 I had a good supply of able,

00:28:27 ambitious, and hard-working

00:28:30 Ph.D. candidates,

00:28:33 including one or two post-doctorals,

00:28:36 not many.

00:28:39 We used to sit around and talk.

00:28:42 It was a very stimulating atmosphere.

00:28:45 Perhaps it's unfair to say,

00:28:48 but I think I bubbled with ideas.

00:28:51 I was interested in all kinds of mechanisms.

00:28:54 It was really obvious.

00:28:57 I nearly anticipated Ingold

00:29:00 on the discovery that

00:29:03 first-order hydrolyses invert the configuration.

00:29:06 He beat me on it by a month or two

00:29:09 on publication of it.

00:29:12 Yes.

00:29:15 I was thinking about lots of things

00:29:18 and talking it over with,

00:29:21 as I say, very able and

00:29:24 imaginative,

00:29:27 very helpful

00:29:30 graduate students.

00:29:33 We all worked together.

00:29:36 I wasn't just working on organic chemistry.

00:29:39 I'd been very much

00:29:42 interested in

00:29:45 Werner's theory of inorganic complexes

00:29:48 by the lectures that I took with

00:29:51 Nelson at Columbia.

00:29:54 Nelson was a very great man

00:29:57 and a very inspiring lecturer.

00:30:00 I learned a great deal from him.

00:30:03 I dug up from some obscure references

00:30:06 that phenanthroline ferrocyan would be

00:30:09 a good oxidation indicator.

00:30:12 Working with a colleague,

00:30:15 a friend that went back to the

00:30:18 wartime days at Pittsburgh,

00:30:21 George Walden,

00:30:24 he and I co-published a number of

00:30:27 papers in that general field.

00:30:30 I was playing around.

00:30:34 Nitration reactions go so fast.

00:30:37 I did work on

00:30:40 matters related to that sort.

00:30:43 The paper with Leonard Lucas

00:30:46 was involved.

00:30:49 Quite a variety of interesting and

00:30:52 exciting things.

00:30:55 The first paper on what eventually became

00:30:58 the Hammett equation was published in 1935.

00:31:02 That didn't use the sigma rho yet,

00:31:05 but you did discuss that.

00:31:08 That was a Chem Reviews article.

00:31:11 It just seemed to be an expansion

00:31:14 and an update of the Flueger material.

00:31:20 Actually, there was an English fellow

00:31:23 who had some of these same ideas

00:31:26 and he published in 1936.

00:31:30 Burckhardt in Manchester.

00:31:33 I don't think he ever did anything else

00:31:36 in that general area.

00:31:39 Wengold always referred to this as

00:31:42 the Hammett-Burckhardt equation.

00:31:45 I met Burckhardt

00:31:48 at a meeting in Manchester

00:31:51 of the Faraday Society.

00:31:54 A very pleasant chap,

00:31:58 and the Hammett equation,

00:32:01 so-called,

00:32:07 was almost an obvious idea.

00:32:10 Burckhardt had just shown that you could

00:32:13 compare two different reactions and get

00:32:16 linear relations on the logarithms,

00:32:19 even though they seemed unrelated.

00:32:22 But I got the idea of comparing them all

00:32:26 to a single origin, so to speak.

00:32:29 That's where sigma and rho come in.

00:32:32 Here I have a slide

00:32:35 of the Hammett equation

00:32:38 with sigma being the substituent constant

00:32:41 and rho the reaction constant.

00:32:44 I guess it was in the second edition

00:32:47 of your book on physical organic chemistry

00:32:50 you had said it would be

00:32:54 hypocritical humility for me to pretend

00:32:57 that I do not know that this equation

00:33:00 is commonly called the Hammett equation

00:33:03 or that I am not grateful to those

00:33:06 who have honored me in this way.

00:33:09 I can honestly say that I did not initiate

00:33:12 the usage and I have hitherto done

00:33:15 nothing to promote it.

00:33:18 But I think it's just the Hammett equation.

00:33:22 It's almost a national industry

00:33:25 in one of the small European countries,

00:33:28 but chemists have made their name

00:33:31 on the Hammett equation for many years.

00:33:34 There's a fellow in Czechoslovakia

00:33:37 whom I admire very much

00:33:40 who's worked a lot on it.

00:33:46 In the 1937 paper you calculated

00:33:49 30 sigma constants and some 40

00:33:52 rho's for 40 reactions.

00:33:55 Can you tell me something about that work?

00:33:58 It was done with an old-fashioned computer.

00:34:08 I'm not sure whether I started out

00:34:11 with a hand-operated one or

00:34:14 with an electrical-operated one.

00:34:17 I remember in particular it didn't

00:34:20 have automatic division,

00:34:23 which was a handicap.

00:34:26 This slide shows some of the relationships

00:34:29 that you had and the linearity

00:34:32 of some of the relationships.

00:34:35 The top two here are actually

00:34:38 equilibrium constants for two other

00:34:41 kinds of acids.

00:34:45 The two lower ones are rate constants

00:34:48 versus sigma.

00:34:51 Again, you see the real linearity.

00:34:54 I'd like to point out the scatter

00:34:57 that there is around them.

00:35:00 It looks as if this was a relatively

00:35:03 very poor relationship.

00:35:06 These look like very good ones,

00:35:09 but if you calculate the actual

00:35:12 slope, it exaggerates.

00:35:15 As the low slope saturates,

00:35:18 it exaggerates the deviations.

00:35:21 You calculated the deviations as well?

00:35:24 I calculated the deviations always.

00:35:27 That was almost automatic when you

00:35:30 did all these squares.

00:35:33 This was getting toward the end of the 30s.

00:35:36 You must have been thinking about

00:35:39 that a lot.

00:35:42 I don't know exactly what started me

00:35:45 thinking about it.

00:35:48 Since you asked me about it,

00:35:51 I've been trying to think back.

00:35:54 You told me just a few minutes ago

00:35:57 that we were talking about the days

00:36:00 at Harvard and your thoughts about

00:36:03 how things hadn't really been

00:36:07 Well, yes.

00:36:10 My experience in organic chemistry

00:36:13 with Kohler, with Sautinger,

00:36:16 and with Eisenman,

00:36:19 I felt dissatisfied with

00:36:22 organic chemistry.

00:36:25 I quoted one of my colleagues

00:36:28 saying that the beauty of organic

00:36:31 chemistry is that you can start out

00:36:34 pharmaceutical and vice versa.

00:36:37 That was the fun of it.

00:36:40 Well, that wasn't my idea of fun.

00:36:43 Can you give me some idea of how

00:36:46 the book was written and who you

00:36:49 were talking to at that time?

00:36:52 I can remember reading sections

00:36:55 of it, the drafts, to my students.

00:36:58 In fact, we used to sit around

00:37:01 and talk about the direction of this book.

00:37:04 I got their comments.

00:37:07 But the idea of writing a book

00:37:10 just grew out of my own head.

00:37:13 Nobody influenced me particularly

00:37:16 in that direction.

00:37:19 Here we have a copy of the book.

00:37:22 Here's a fancy bound version of it

00:37:25 that McGraw-Hill gave you.

00:37:28 Here are 25 original references

00:37:31 in the book, too.

00:37:34 It just had an enormous impact

00:37:37 on the development of chemistry.

00:37:40 I thought at one time or another

00:37:43 that it probably just set up a

00:37:46 research program for organic

00:37:49 chemistry for the next 20 years.

00:37:52 That's a very gratifying situation.

00:37:55 I think what really strikes me

00:37:58 is just the clarity of it.

00:38:01 How did you learn to write like that?

00:38:04 Did you ever consciously study it?

00:38:07 Maybe it was English A at Harvard.

00:38:10 I hated it.

00:38:13 Something really came through

00:38:16 in your papers and in the book itself.

00:38:19 There's just a certain simplicity

00:38:22 that McGraw-Hill seemed to manage.

00:38:25 You told me something about how

00:38:28 Roger Adams reacted to the book.

00:38:31 The National Academy of Sciences

00:38:34 chemistry group used to meet

00:38:37 in two groups.

00:38:40 There was a group of organic

00:38:43 chemists and there was a group

00:38:46 of physical chemists.

00:38:49 I came to one of the meetings

00:38:52 and I was flocking with the

00:38:55 physical chemists on one side

00:38:58 of the room and Adams motioned

00:39:01 to me, he said, come over here

00:39:04 you belong with us.

00:39:07 Another compliment I had was that

00:39:10 when Hugh Taylor of Princeton

00:39:13 told me it must be a good book

00:39:17 Shortly after the book came out...

00:39:20 Then the Second World War came along

00:39:23 and I wanted to get into it.

00:39:26 I was sent to Europe by the

00:39:29 Office of Scientific Research and

00:39:32 Development and I spent a considerable

00:39:35 part of a summer traveling around

00:39:38 England, visiting all kinds of

00:39:41 war research activities

00:39:45 including particularly those

00:39:48 involved with rocket propellants

00:39:51 which were a new thing then.

00:39:54 Came back to this country and

00:39:57 Kistiakowsky had organized an

00:40:00 explosive research laboratory at

00:40:03 Brewston, which is just outside

00:40:06 of Pittsburgh, and the laboratory

00:40:09 was a center for research on all

00:40:12 kinds of rocket propellants and

00:40:15 high explosives. Frank Westheimer

00:40:18 was on the staff in charge of

00:40:21 organic chemistry work there.

00:40:24 His wife said she didn't know what

00:40:27 he was working on because it was

00:40:30 classified material, but she knew

00:40:33 it wasn't explosives because the

00:40:36 laboratory was listed in the

00:40:39 Explosive Research Laboratory and

00:40:42 her husband had already become

00:40:45 interested in biological science.

00:40:48 When Frank was there and Frank

00:40:51 Long, and then I came back to

00:40:54 Columbia and I wanted very

00:40:57 desperately to be in university

00:41:00 life again. In spite of my refusal

00:41:03 to take jobs elsewhere that

00:41:06 I got inveigled into being head

00:41:09 of the Department of Columbia and

00:41:12 I ran that job for six years.

00:41:15 And I was still doing research

00:41:18 and several new ideas, some of

00:41:21 them very prolific and fertile.

00:41:24 I think particularly we did some

00:41:27 good work on temperature

00:41:30 coefficients and I got very much

00:41:33 interested in whether changes in

00:41:36 structure worked through the

00:41:39 enthalpy or through the entropy

00:41:42 and things of that sort and we got

00:41:45 some good papers out on that.

00:41:48 And I had become interested in

00:41:51 ion exchange resins as catalysts

00:41:54 through my consulting work with

00:41:57 the Roman Haas and I had several

00:42:00 of a technique for measuring

00:42:03 reaction rates by stirred flow

00:42:06 reactors and I had a number of

00:42:09 good students and postdoctoral

00:42:12 people working on that. By that

00:42:15 time federal money was very, very

00:42:18 available and I could work on

00:42:21 practically anything I wanted to

00:42:24 thanks to the Naval Research

00:42:27 although being administrative

00:42:30 officer, which wasn't a job I ever

00:42:33 wanted, but I had to take and I

00:42:36 think I did pretty well. We had

00:42:39 some crises. One time while I was

00:42:42 there I became essentially short

00:42:45 out of organic chemists and I was

00:42:48 able to bring in Stork and Breslow

00:42:51 and Walling and we ended up with a

00:42:54 chemical group there and I take

00:42:57 responsibility for that. Then in

00:43:00 1961 I retired and I moved to the

00:43:03 country, did a lot of consulting

00:43:06 work, traveled all over the world,

00:43:09 learned things from my consulting

00:43:12 work. In fact that's what put me

00:43:15 on to as much as anything. I was a

00:43:18 resident consultant at the Carbide

00:43:21 Research Laboratory for several

00:43:24 months. One of the men up there

00:43:27 discovered a different acidity

00:43:30 function based on different bases

00:43:33 and Frank Long had found some

00:43:36 things of that sort. So those

00:43:39 contributed to the sort of thing

00:43:42 that ended up in the second edition

00:43:45 of my physical organic chemistry.

00:43:48 Well it was a fun time and then I

00:43:51 got on to the board of directors of

00:43:54 the American Chemical Society and I

00:43:57 was chairman of the committee on

00:44:00 publications. I was chairman of the

00:44:03 committee on grants and fellowships

00:44:06 and I ended up as chairman of the

00:44:09 board for a year and then I retired

00:44:12 from that and my job at Columbia in

00:44:15 the United States was to be a

00:44:18 physical organic chemist. I had a

00:44:21 good time ever since. There were

00:44:24 certainly several very busy periods

00:44:27 in your life. It's sort of

00:44:30 interesting that your book, Physical

00:44:33 Organic Chemistry, essentially named

00:44:36 the sort of subfield called physical

00:44:39 organic chemistry. I haven't run

00:44:42 into that. They have spread out.

00:44:45 Most of them came out, at least

00:44:48 those who came out in the pre-war

00:44:51 period, had hard times getting a job

00:44:54 and one of them was being interviewed

00:44:57 for a job and was asked what kind of

00:45:00 a chemist he was. He said he was a

00:45:03 physical organic chemist and this

00:45:06 industrial recruiter said, well what

00:45:09 kind of a chemist is that? We know

00:45:12 what physical chemists are. They

00:45:15 teach us how to measure what we're

00:45:18 working with and we know what organic

00:45:21 chemists are. They teach us how to

00:45:24 make new organic compounds. Physical

00:45:27 organic chemists I never heard of.

00:45:30 Louis, it's been an absolute delight

00:45:33 to talk to you. Well, I've enjoyed it

00:45:36 I've enjoyed it a lot.