Chemical synthesis

“ If the reader has yet acquired any real taste for chemical truths, he will wish to see this analysis confirmed by synthesis; that is, in common language, he will wish to see sulphur actually made by combining its acid with an inflammable principle. It seldom happens that chemists can reproduce the original bodies, though they combine together all the principles into which they have analyzed them; in the instance, however, before us, the reproduction of the original substance will be found complete. ”

“ Proceeding to another class of miracles, which seem at first to be creative, we shall find that they also come within the range of familiar human potentiality. The making of bread, or meal, or oil, or wine, are instances of chemical synthesis. These substances are composed of three or four elements, all gaseous except carbon (to be absolutely accurate, we must add minute quantities of eight other elements) , which no chemist has yet succeeded in uniting in such forms. ”

“ It has been so fruitful in its many applications and in the foreshadowing of remote consequences, especially respecting carbon compounds, that it is impossible to deny its claims to be ranked as a great achievement of chemical science. Its practical application to the synthesis of many substances of the most complicated composition entering into the structure of organised bodies, and to the creation of an unlimited number of carbon compounds, among which the colours derived from coal tar stand prominently forward, surpass the synthetical powers of Nature itself. ”

“ Belief in the mysterious vital force operating in living beings received a rude shock at the hands of Wohler, sixty years ago, and successive triumphs in synthesis have dispelled it entirely, so far as non-organized bodies are concerned: "To-day we know that the same chemical laws rule animate and inanimate nature, and that any definite compound produced in the former can be prepared by synthesis as soon as its chemical constitution has been made out." ”

“ But the most interesting and most promising of all is the complete inorganic synthesis that dispenses with the aid of vegetation and starts with coal and lime. These heated together in the electric furnace form calcium carbide and this, as every automobilist knows, gives acetylene by contact with water. From this gas isoprene can be made and the isoprene converted into rubber by sodium, or acid or alkali or simple heating. Acetone, which is also made from acetylene, can be converted directly into rubber by fuming sulfuric acid. ”

“ At the present time the aspect of the field of chemical research is quite altered. It is true that the analysis of complex substances is not neglected. The tar products alone number many hundred, and include many bodies useful, not only in manufactures, but also in medicine. But the synthesis, or building up of new combinations formerly supposed to be the appanage of organized beings, is now going forward in most of the chief laboratories of chemistry. ”

“ The experiments by which the chemical analysis or synthesis of various forms of matter is demonstrated are simple or compound applications of this method of Difference, together with the quantitative mark of causation (that cause and effect are equal) ; since the bodies resulting from an analysis are equal in weight to the body analysed, and the body resulting from a synthesis is equal in weight to the bodies synthesised. That an electric current resolves water into oxygen and hydrogen may be proved by inserting the poles of a galvanic battery in a vessel of water ”

“ The synthesis of other so-called organic compounds followed, and at present it is known that the same chemical laws apply to all substances whether formed in the living organism or prepared in the laboratory from inorganic constituents. ”

“ In studies of the laboratory synthesis of life-related compounds and its significance concerning the origin of life, several results seem to suggest that organochemical synthesis is a general process, occurring perhaps on all planets which retain a reducing atmosphere. The temperature ranges must be such that precursors and reaction products are not thermally dissociated. ”

“ Syntheses of Organic Acids.—The simplest syntheses are undoubtedly those in which a carboxyl group is obtained directly from the oxides of carbon, carbon dioxide and carbon monoxide. The simplest of all include: (1) the synthesis of sodium oxalate by passing carbon dioxide over metallic sodium heated to 350°–360°; (2) the synthesis of potassium formate from moist carbon dioxide and potassium, potassium carbonate being obtained simultaneously; (3) the synthesis of potassium acetate and propionate from carbon dioxide and sodium methide and sodium ethide ”

“ When a precipitate is dissolved by the addition of a reagent, such as an acid, an alkali, ammonia, ammonium sulphide—chemical solvents most frequently used in analytical work—we may, as a general principle, consider that the reagent must affect one or both of the ions of the precipitate in question, suppressing it (or them) and thereby making solution possible. The problem of determining in what way the suppression of the ion is effected, must then be faced. ”

“ In organic as in inorganic chemistry, atoms are bound together by chemical affinity, though it was formerly supposed that an additional or vital force was instrumental in forming organic compounds. For this reason none of these substances, it was thought, could be built up in the laboratory, although many had been analyzed. In 1828 the first organic compound, urea, was artificially prepared, and since then thousands have been synthesized. They are not necessarily manufactured from organic products, but can be made from mineral matter. ”

“ In the formation of formic acid from carbonic oxide we observe an example of the synthesis of organic compounds, such as are now very numerous, and are treated of in detail in works on organic chemistry. ”

“ Bayliss defines enzymes as the “catalysts produced by living organisms.” A catalyst is a body which greatly accelerates the rate of reaction in chemical processes, without apparently taking part in the process. For instance, peroxide of hydrogen is decomposed into oxygen and water by mere contact with finely divided platinum, while the latter remains unaltered in the process. ”

“ Our chemists found that starting with simple substances they could, by proper means, combine them into molecules of greater complexity, and in so doing could make many of the compounds that had hitherto been produced only as a result of living activities. For example, urea, formic acid, indigo, and many other bodies, hitherto produced only by animals and plants, were easily produced by the chemist by purely chemical methods. ”

“ The view long maintained—until late in the nineteenth century, in fact—that organic and inorganic chemistry are separated from each other by a wide gap, is no longer held. Hundreds of organic substances, some of them of great complexity, have been made in the chemist’s laboratory, and can now be classed as properly with inorganic as with organic substances. The gap has been closed, and there is now but one chemistry. Only the most intricate chemical compounds still lie beyond the chemist’s grasp, and the isolation of these may be at any time overthrown. ”

“ Most cases of synthesis take place with great facility, automatically in fact, for, when coal is burned, we start the fire, and after that the oxygen and carbon unite to form carbonic acid, without any further effort on our part. ”

“ When oxygen combines with a single element, what is the compound called? We have found that O makes up a certain portion of the air; later, we shall see how large the proportion is. Its tendency to combine with almost everything is a reason for the decay, rust, and oxidation of so many substances, and for conflagrations, great and small. New compounds are thusformed, of which O constitutes one factor. Water, H2O, is only a chemical union of O and H. Iron rust, Fe2O3 and H2O, is composed of O, Fe, and water. The burning of wood or of coal gives rise to carbon dioxide, CO2, and water. ”

“ Acids and bases appear to act catalytically upon all reactions involving consumption or liberation of water, and indeed that action is proportional to the concentration of the hydrogen or hydroxyl-ions. Further, the decomposition of hydrogen peroxide is “catalysed” by iodine-ions, the condensation of two molecules of benzaldehyde to benzoin by cyanogen-ions. One of the earliest known and technically most important instances of catalysis is that of the oxidation of sulphur dioxide to sulphuric acid by oxygen in the presence of oxides of nitrogen. ”

“ An important nucleus-synthetic reaction is the saponification of nitriles, which may be obtained by the interaction of potassium cyanide with a halogen substitution derivative or a sulphonic acid.
Acids frequently result as oxidation products, being almost invariably formed in all cases of energetic oxidation. There are certain reactions, however, in which oxidation can be successfully applied to the synthesis of acids. Thus primary alcohols and aldehydes, both of the aliphatic and aromatic series, readily yield on oxidation acids containing the same number of carbon atoms. ”

“ The most interesting and, in many respects, the most important, development of the last twenty-five years has been in electro-chemistry. Electro-chemical methods are now employed for the production of a large number of elements, such as the alkali and alkaline earth metals, copper, zinc, aluminum, chromium, manganese, the halogens, phosphorus, hydrogen, oxygen, and ozone; various chemicals, including the mineral acids, hydrates, chlorates, hypochlorites, chromates, permanganates, disinfectants, alkaloids, coal tar dyes, and various carbon compounds ”

“ Oxygen and nitrogen, nitrogen and hydrogen, hydrogen and carbon, which show no affinity for each other under ordinary circumstances, readily unite when one or both are in a nascent condition. The reason seems to be that, when the elements of a compound are torn asunder, the chemical affinity which previously bound them together is set free, ready and eager to unite the nascent elements with whatever they come in contact with. ”

“ But as soon as the solution is rendered stronger, or the solvent and the dissolved body are endowed with a mutual chemical affinity, chemical reactions set in. Part of the molecules of the dissolved body dissociate, and the atoms of which they were composed, on being set free, combine with the atoms of the solvent. Chemical forces, much more energetic than the physical forces, enter into play, and most complicated chemical reactions—the intensity of which may be judged of from the changes of temperature—begin. ”

“ It brings home to me what an unstable chemical compound man is. Here are the stage accessories as good as ever, while the players have all split up into hydrogen and oxygen and nitrogen and carbon, with traces of iron and silica and phosphorus. ”

“ Of the highly complex series of albuminoid substances, which neither crystallize nor possess any combining equivalent, and therefore can not be expressed by exact symbols, analytic chemistry knows but little, and hence it would be in vain to attempt their reproduction by synthesis. Notwithstanding our ignorance of essential facts, the progress of synthetic chemistry has been great, and the prospect is favorable for more brilliant achievements in the future. ”

“ It was formerly supposed that the substances found in plants and animals, mostly complex compounds of carbon, hydrogen and oxygen, could only be produced by "vital forces." If this were true it meant that chemistry was limited to the mineral kingdom and to the extraction of such carbon compounds as happened to exist ready formed in the vegetable and animal kingdoms. But fortunately this barrier to human achievement proved purely illusory. The organic field, once man had broken into it, proved easier to work in than the inorganic. ”

“ Hence, reactions between organic compounds, even when they are in solution, proceed very slowly unless carried on at high temperatures, under increased pressure, or under the influence of some catalytic agent. Even under the stimulation of these reaction-accelerating agencies, most chemical changes in organic compounds when carried on in the laboratory, require several hours or even days and sometimes weeks, for their completion. But when similar reactions take place in living organisms, they proceed with velocities which resemble those of inorganic compounds in the laboratory. ”

“ Inorganic bodies, such as metals, may enter into albuminous combinations which may greatly modify their effects, and organic substances may be split up into simpler compounds by oxidation or reduction, or may be rendered more complex by synthesis. ”

“ Whether we have here an instantaneous action between non-ionized molecules, as claimed by the observer, or whether the minimal ionization157 of the hydrogen chloride and copper oleate, the existence of which we have a right to assume, is sufficient to account for this rapid action, both components being in solution and intimately mixed, is a question of the greatest interest. ”

“ But it may be convenient to treat the subject of the artificial production of this group of bodies rather more comprehensively and as a sub-section of this chapter on organic synthesis, since their formation by such means constitutes a phase in the development of chemistry, and has undoubtedly exercised a profound influence on scientific thought and on philosophical and even theological doctrine. During the past fifty or sixty years the chemist has been enabled to form the active principles or characteristic products of many plants and animals. ”