…we all had to learn a number of XIXth century rules—such as Markownikov’s rule for addition to olefins, Thiele’s 1:4—addition rules for conjugated systems and Crum Brown’s rule for aromatic substitution. It was just like learning Latin grammar.

[The nanotube] brings those properties you cannot get from other organic molecules. And it’s still carbon, so it has organic chemistry. Here is an object that has, to a superlative degree, the aspects that we hold most central to the inorganic world: hardness, toughness, terrific strength, thermal and electrical conductivity. Things you just can’t do with bone and wood. But it’s made out of carbon. It’s something that plays the game at the same level of perfection as molecules and life.

[The] structural theory is of extreme simplicity. It assumes that the molecule is held together by links between one atom and the next: that every kind of atom can form a definite small number of such links: that these can be single, double or triple: that the groups may take up any position possible by rotation round the line of a single but not round that of a double link: finally that with all the elements of the first short period [of the periodic table], and with many others as well, the angles between the valencies are approximately those formed by joining the centre of a regular tetrahedron to its angular points. No assumption whatever is made as to the mechanism of the linkage. Through the whole development of organic chemistry this theory has always proved capable of providing a different structure for every different compound that can be isolated. Among the hundreds of thousands of known substances, there are never more isomeric forms than the theory permits.

An diesen Apparate ist nichts neu als seine Einfachkeit und die vollkommene zu Verlaessigkeit, welche er gewaehst.
In this apparatus is nothing new but its simplicity and thorough trustworthiness.
On his revolutionary method of organic analysis.

And so, after many years, victory has come, and the romance of exploration, of high hopes and bitter disappointment, will in a few years simply be recorded in the text-books of organic chemistry in a few terse sentences.

Be a physical chemist, an organic chemist, an analytical chemist, if you will; but above all be a Chemist.
[Admonishing his students to avoid over-specialization.]

But if we are to control evolution we shall have to find out how to influence gene reproduction in a definite direction, just as organic chemists nowadays work for definite ends. Such a possibility is at present entirely beyond our grasp, but a century hence it may not be so.

Every chemical substance, whether natural or artificial, falls into one of two major categories, according to the spatial characteristic of its form. The distinction is between those substances that have a plane of symmetry and those that do not. The former belong to the mineral, the latter to the living world.

I am afraid I shall have to give up my trade; I am far too inert to keep up with organic chemistry, it is becoming too much for me, though I may boast of having contributed something to its development. The modern system of formulae is to me quite repulsive.

I am an organic chemist, albeit one who adheres to the definition of organic chemistry given by the great Swedish chemist Berzelius, namely, the chemistry of substances found in living matter, and my science is one of the more abstruse insofar as it rests on concepts and employs a jargon neither of which is a part of everyday experience. Nevertheless, organic chemistry deals with matters of truly vital Importance and in some of its aspects with which I myself have been particularly concerned it may prove to hold the keys to Life itself.

I do not believe that the present flowering of science is due in the least to a real appreciation of the beauty and intellectual discipline of the subject. It is due simply to the fact that power, wealth and prestige can only be obtained by the correct application of science.

I have always felt that I understood a phenomenon only to the extent that I could visualise it. Much of the charm organic chemical research has for me derives from structural formulae. When reading chemical journals, I look for formulae first.

I have always had the feeling that organic chemistry is a very peculiar science, that organic chemists are unlike other men, and there are few occupations that give more satisfactions [sic] than masterly experimentation along the old lines of this highly specialised science.

I hope that in due time the chemists will justify their proceedings by some large generalisations deduced from the infinity of results which they have collected. For me I am left hopelessly behind and I will acknowledge to you that through my bad memory organic chemistry is to me a sealed book. Some of those here, [August] Hoffman for instance, consider all this however as scaffolding, which will disappear when the structure is built. I hope the structure will be worthy of the labour. I should expect a better and a quicker result from the study of the powers of matter, but then I have a predilection that way and am probably prejudiced in judgment.

I liked science. I wasn’t mathematically oriented, so I became an organic chemist.

I suppose I should be run after for a professorship if I had studied at Giessen, as it seems to be a settled point that no young man can be expected to know anything of chemistry unless he has studied with Liebig; while the truth is, that any one who goes there and does not afterwards correct the bad habits acquired there, in some other laboratory, is almost unfitted for doing things in Chemistry. No doubt Liebig is a remarkable man, who has done much for organic Chemistry, not to speak of his having quarreled with all the Chemists in Europe...

I think chemistry is being frittered away by the hairsplitting of the organic chemists; we have new compounds discovered, which scarcely differ from the known ones and when discovered are valueless—very illustrations perhaps of their refinements in analysis, but very little aiding the progress of true science.

In inorganic chemistry the radicals are simple; in organic chemistry they are compounds—that is the sole difference.

In organic chemistry there exist certain types which are conserved even when, in place of hydrogen, equal volumes of chlorine, of bromine, etc. are introduced.

In the benzene nucleus we have been given a soil out of which we can see with surprise the already-known realm of organic chemistry multiply, not once or twice but three, four, five or six times just like an equivalent number of trees. What an amount of work had suddenly become necessary, and how quickly were busy hands found to carry it out! First the eye moves up the six stems opening out from the tremendous benzene trunk. But already the branches of the neighbouring stems have become intertwined, and a canopy of leaves has developed which becomes more spacious as the giant soars upwards into the air. The top of the tree rises into the clouds where the eye cannot yet follow it. And to what an extent is this wonderful benzene tree thronged with blossoms! Everywhere in the sea of leaves one can spy the slender hydroxyl bud: hardly rarer is the forked blossom [Gabelblüte] which we call the amine group, the most frequent is the beautiful cross-shaped blossom we call the methyl group. And inside this embellishment of blossoms, what a richness of fruit, some of them shining in a wonderful blaze of color, others giving off an overwhelming fragrance.

It may sound like a lot of work to keep up with organic chemistry, and it is; however, those who haven't the time to do it become subject to decay in the ability to teach and to contribute to the Science—a sort of first-order process the half-life of which can't be much more than a year or two.

Of the nucleosides from deoxyribonucleic acids, all that was known with any certainty [in the 1940s] was that they were 2-deoxy-­D-ribosides of the bases adenine, guanine, thymine and cytosine and it was assumed that they were structurally analogous to the ribonucleosides. The chemistry of the nucleotides—the phosphates of the nucleosides—was in a correspondingly primitive state. It may well be asked why the chemistry of these groups of compounds was not further advanced, particularly since we recognize today that they occupy a central place in the history of the living cell. True, their full significance was for a long time unrecognized and emerged only slowly as biochemical research got into its stride but I think a more important reason is to be found in the physical properties of compounds of the nucleotide group. As water-soluble polar compounds with no proper melting points they were extremely difficult to handle by the classic techniques of organic chemistry, and were accordingly very discouraging substances to early workers. It is surely no accident that the major advances in the field have coincided with the appearance of new experimental techniques such as paper and ion-exchange chromatography, paper electrophoresis, and countercurrent distribution, peculiarly appropriate to the compounds of this group.

One of the most immediate consequences of the electrochemical theory is the necessity of regarding all chemical compounds as binary substances. It is necessary to discover in each of them the positive and negative constituents... No view was ever more fitted to retard the progress of organic chemistry. Where the theory of substitution and the theory of types assume similar molecules, in which some of the elements can be replaced by others without the edifice becoming modified either in form or outward behaviour, the electrochemical theory divides these same molecules, simply and solely, it may be said, in order to find in them two opposite groups, which it then supposes to be combined with each other in virtue of their mutual electrical activity... I have tried to show that in organic chemistry there exist types which are capable, without destruction, of undergoing the most singular transformations according to the nature of the elements.

One of the most striking evidences of the reliability of the organic chemist's methods of determining molecular structure is the fact that he has never been able to derive satisfactory structures for supposed molecules which are in fact nonexistent.

Organic Chemistry has become a vast rubbish heap of puzzling and bewildering compounds.

Organic chemistry has literally placed a new nature beside the old. And not only for the delectation and information of its devotees; the whole face and manner of society has been altered by its products. We are clothed, ornamented and protected by forms of matter foreign to Nature; we travel and are propelled, in, on and by them. Their conquest of our powerful insect enemies, their capacity to modify the soil and control its microscopic flora, their ability to purify and protect our water, have increased the habitable surface of the earth and multiplied our food supply; and the dramatic advances in synthetic medicinal chemistry comfort and maintain us, and create unparalleled social opportunities (and problems).

Organic chemistry is the chemistry of carbon compounds. Biochemistry is the study of carbon compounds that crawl.

Organic chemistry is the study of organs; inorganic chemistry is the study of the insides of organs.

Organic chemistry just now is enough to drive one mad. It gives me the impression of a primeval forest full of the most remarkable things, a monstrous and boundless thicket, with no way of escape, into which one may well dread to enter.

Suppose [an] imaginary physicist, the student of Niels Bohr, is shown an experiment in which a virus particle enters a bacterial cell and 20 minutes later the bacterial cell is lysed and 100 virus particles are liberated. He will say: “How come, one particle has become 100 particles of the same kind in 20 minutes? That is very interesting. Let us find out how it happens! How does the particle get in to the bacterium? How does it multiply? Does it multiply like a bacterium, growing and dividing, or does it multiply by an entirely different mechanism ? Does it have to be inside the bacterium to do this multiplying, or can we squash the bacterium and have the multiplication go on as before? Is this multiplying a trick of organic chemistry which the organic chemists have not yet discovered ? Let us find out. This is so simple a phenomenon that the answers cannot be hard to find. In a few months we will know. All we have to do is to study how conditions will influence the multiplication. We will do a few experiments at different temperatures, in different media, with different viruses, and we will know. Perhaps we may have to break into the bacteria at intermediate stages between infection and lysis. Anyhow, the experiments only take a few hours each, so the whole problem can not take long to solve.”
[Eight years later] he has not got anywhere in solving the problem he set out to solve. But [he may say to you] “Well, I made a slight mistake. I could not do it in a few months. Perhaps it will take a few decades, and perhaps it will take the help of a few dozen other people. But listen to what I have found, perhaps you will be interested to join me.”

The artificial products do not have any molecular dissymmetry; and I could not indicate the existence of a more profound separation between the products born under the influence of life and all the others.

The elements of the living body have the chemical peculiarity of forming with each other most numerous combinations and very large molecules, consisting of five, six or even seven different elements.

The structural formula of the organic chemist is not the canvas on which the cubist artist should impose his drawings which he alone can interpret.

The structural theory of Kekulé has been the growth hormone of organic chemistry.
Co-author with Melville Calvin (1911-1997)

The synthesis of substances occurring in Nature, perhaps in greater measure than activities in any other area of organic chemistry, provides a measure of the conditions and powers of science.

This investigation has yielded an unanticipated result that reaction of cyanic acid with ammonia gives urea, a noteworthy result in as much as it provides an example of the artificial production of an organic, indeed a so-called animal, substance from inorganic substances.
[The first report of the epoch-making discovery, that an organic compound can be produced from inorganic substances.]

Those of us who were familiar with the state of inorganic chemistry in universities twenty to thirty years ago will recall that at that time it was widely regarded as a dull and uninteresting part of the undergraduate course. Usually, it was taught almost entirely in the early years of the course and then chiefly as a collection of largely unconnected facts. On the whole, students concluded that, apart from some relationships dependent upon the Periodic table, there was no system in inorganic chemistry comparable with that to be found in organic chemistry, and none of the rigour and logic which characterised physical chemistry. It was widely believed that the opportunities for research in inorganic chemistry were few, and that in any case the problems were dull and uninspiring; as a result, relatively few people specialized in the subject... So long as inorganic chemistry is regarded as, in years gone by, as consisting simply of the preparations and analysis of elements and compounds, its lack of appeal is only to be expected. The stage is now past and for the purpose of our discussion we shall define inorganic chemistry today as the integrated study of the formation, composition, structure and reactions of the chemical elements and compounds, excepting most of those of carbon.

To many physical chemists in the 1920's and early 1930's, the organic chemist was a grubby artisan engaged in an unsystematic search for new compounds, a search which was strongly influenced by the profit motive.

We define organic chemistry as the chemistry of carbon compounds.

We may regard [Scheele] not only as having given the first indication of the rich harvest to be reaped by the investigation of the compounds of organic chemistry, but as having been the first to discover and make use of characteristic reactions by which closely allied substances can be detected and separated, so that he must be considered one of the chief founders of analytical chemistry.

We may regard the cell quite apart from its familiar morphological aspects, and contemplate its constitution from the purely chemical standpoint. We are obliged to adopt the view, that the protoplasm is equipped with certain atomic groups, whose function especially consists in fixing to themselves food-stuffs, of importance to the cell-life. Adopting the nomenclature of organic chemistry, these groups may be designated side-chains. We may assume that the protoplasm consists of a special executive centre (Leistungs-centrum) in connection with which are nutritive side-chains… The relationship of the corresponding groups, i.e., those of the food-stuff, and those of the cell, must be specific. They must be adapted to one another, as, e.g., male and female screw (Pasteur), or as lock and key (E. Fischer).