Speaker 1: Section seventeen of the Science History of the Universe, Volume four.
Speaker 1: This is a LibriVox recording. All LibriVox recordings are in
Speaker 1: the public domain. For more information or to volunteer, please
Speaker 1: visit LibriVox dot org. Recording by Avay in June twenty seventeen,
Speaker 1: The Science History of the Universe, Volume four, edited by
Speaker 1: Francis Rold Wheeler. Chemistry, Chapter thirteen, valence the constitution of
Speaker 1: organic compounds and the development of stereochemistry. In the preceding chapter.
Speaker 1: Mention has been made of the influence exerted by Frankland
Speaker 1: on the views developed by Colbert respecting the constitution of
Speaker 1: organic compounds. It was Frankland who, in his now classical
Speaker 1: paper A New Series of Organic Compounds containing metals, demonstrated
Speaker 1: that the peering of the radicals with the elements was
Speaker 1: to be explained on the ground of some characteristic property
Speaker 1: of the atoms, and thus he expelled the useless part
Speaker 1: of the radical theory. Eighteen fifty two. Frankland observed that
Speaker 1: when the formulae of inorganic chemical compounds are considered, even
Speaker 1: a superficial observer is struck with the general symmetry of
Speaker 1: their constitution. The compounds of nitrogen, phosphorus, antimony, and arsenic
Speaker 1: especially exhibit the tendency of these elements to form compounds
Speaker 1: containing three or five equivalents of other elements, and it
Speaker 1: is in these proportions that their affinities are best satisfied. Thus,
Speaker 1: an eternal group, we have no three n H three,
Speaker 1: n I three N S three, p O three, p
Speaker 1: H three, pc L three, s BO three, s b
Speaker 1: h three, s p c L three A s O
Speaker 1: three a s H three A s c L three,
Speaker 1: et cetera. And in the five atom group n O five,
Speaker 1: n H four O, n H four I, p O five,
Speaker 1: p H four i, et cetera. Without offering any hypothesis
Speaker 1: regarding the cause of this symmetrical grouping of atoms, it
Speaker 1: is sufficiently evident from the examples just given that such
Speaker 1: a tendency or law prevails, and that, no matter what
Speaker 1: the character of the uniting atoms may be, the combining
Speaker 1: power of the attracting element, if I may be allowed
Speaker 1: to term, is always satisfied by the same number of
Speaker 1: these atoms. End quote. He then proceeded to represent the
Speaker 1: organometallic compounds obtained by formulae, which brought out the analogy
Speaker 1: with the inorganic types from which they were thought to
Speaker 1: have been derived. From his work on the organometallic compounds,
Speaker 1: Franklin developed the doctrine of the valance of the elements,
Speaker 1: the germ of which may be recognized in much that
Speaker 1: has gone before, particularly in the law of multiple proportions,
Speaker 1: which stated that the elements show different yet definite stages
Speaker 1: in their combinations. The so called doctrine of the polybasic
Speaker 1: acids contributed materially to the development of ideas upon the
Speaker 1: subject of the saturation capacity of the atoms. Galusac, Gmelin,
Speaker 1: and others inclined to the assumption that the atoms of
Speaker 1: the various metallic oxides contained one atom of oxygen united
Speaker 1: to one atom of metal, and that these oxides combined
Speaker 1: with one atom of acid to form neutral salts. Versalius,
Speaker 1: also after sixteen twenty eight, considered that this combining proportion
Speaker 1: was the rule. However, by Thomas Graham's famous investigation of
Speaker 1: the phosphoric acids eighteen thirty three, it was shown that
Speaker 1: a view so simple as this, according to which almost
Speaker 1: every acid was looked upon as monobasic, was untenable. Graham
Speaker 1: proved that in the ortho pyro and metaphosphoric acids. For
Speaker 1: each atom of phosphorus pentoxide, there were three, two and
Speaker 1: one atoms of basic water, these latter being replaced by
Speaker 1: equivalent amounts of metallic oxides. The saturation capacities of these
Speaker 1: acids were in this way shown to be dependent upon
Speaker 1: the amounts of basic water which entered into their constitution.
Speaker 1: Libic extended this to many other acids and distinguished between
Speaker 1: mono die and tribasic acid, and the property was referred
Speaker 1: to as the basicity of the atoms, a term which,
Speaker 1: with the ideas inherent in it, clung for some time
Speaker 1: to the theory of valence. In eighteen fifty seven, for example,
Speaker 1: the terms vasicity, valancy, and atomicity were used as synonymous
Speaker 1: and as the measure of the number of hydrogen atoms
Speaker 1: that could be replaced or held in combination. The idea
Speaker 1: of basicity was soon extended to the compound organic radicals.
Speaker 1: In eighteen fifty five, C A voltz eighteen seventy to
Speaker 1: eighteen eighty four, a pupil of Libic and Duma showed
Speaker 1: that glycerine C three H eight O three may be
Speaker 1: regarded as the hydrate of the radical C three H five.
Speaker 1: Four years previous, A. W. Williamson eighteen twenty four to
Speaker 1: nineteen O four had expressed the VW that a large
Speaker 1: number of compounds may be referred to the type of water,
Speaker 1: the monobasic acids to one molecule, and the polybasic acids,
Speaker 1: which are of greater molecular complexity, to a condensed water type.
Speaker 1: He wrote, C two H three O H O equals
Speaker 1: acetic acid, s O two H two O two equals
Speaker 1: sulfuric acid. Words now showed that the composition of glycerine
Speaker 1: could be represented by the formula C three H five
Speaker 1: three prime H three O three, which was similar to
Speaker 1: the formula by which, in accordance with the ideas of Williamson,
Speaker 1: ordinary phosphoric acid P O three prime H three O
Speaker 1: three was represented. Gerhardt, in his Trete de chimi organique
Speaker 1: stated that quote, in order to compare the radicals among themselves,
Speaker 1: I proposed to refer them all to the radical of hydrogen,
Speaker 1: and consequently I name them monotomic, diatomic triatomic according to
Speaker 1: the quantity of hydrogen which they are capable of replacing
Speaker 1: in the type H two O, that is, according to
Speaker 1: whether they are equivalent to one, two, or three atoms
Speaker 1: of hydrogen. So, for instance, in alcohol and in ether
Speaker 1: o C two H five oh C two H five
Speaker 1: o C two H five C two H five, the
Speaker 1: radical ethyl is monotomic because it replaces H one atom
Speaker 1: of hydrogen in the type water end quote. The terms
Speaker 1: monotomic and polyatomic had been employed much earlier, but in
Speaker 1: a difference. Thus, in eighteen twenty seven, Presalius called fluorine chlorine,
Speaker 1: et cetera polyatomic because several atoms of these halogens unite
Speaker 1: with a single atom of another element. In eighteen thirty three,
Speaker 1: Gordon des Sante used the same terms to express the
Speaker 1: number of atoms in a molecule, in which sense they
Speaker 1: were used by Kameelin, Clausius and Odling. Williamson attached the
Speaker 1: idea of capacity for saturation or atomicity of the radical,
Speaker 1: to the number of hydrogen atoms capable of substitution, and
Speaker 1: the notion of atomicity was soon extended to the known
Speaker 1: compound radicals and played an important part in the theory
Speaker 1: of types et cetera, which obtained inorganic chemistry. Franklin's speculations
Speaker 1: concerning the substitution value of radicals compared with that of
Speaker 1: elementary atoms were of great importance, yet they did not
Speaker 1: meet with immediate approval. By eighteen fifty eight, however, the
Speaker 1: valence theory had made rapid progress. In this year, August
Speaker 1: Kekule first deduced the balance of carbon from its simplest compounds,
Speaker 1: declaring it to be tetravalent. This had already been recognized
Speaker 1: by Colbert and Franklin, if not expressly stated by them,
Speaker 1: But Caculae rendered further and much greater service by inquiring
Speaker 1: into the manner in which two or more of these
Speaker 1: tetravalent carbons were united with one another. The doctrine of
Speaker 1: atomic chains open and closed sprang from this, and the
Speaker 1: domination of the structural idea in chemistry became complete. In
Speaker 1: the same year, and independently of Caculae, M. S. Cupere
Speaker 1: arrived at conclusions almost identical with those of Caculae. Both
Speaker 1: Caculae and Couperre expressed with absolute definiteness the axiom that
Speaker 1: the atomicity of the elements was to be made use
Speaker 1: of for arriving at the constitution of chemical compounds. The
Speaker 1: idea of the term atomicity had without any doubt been
Speaker 1: introduced by Franklin six years previous to this. The further
Speaker 1: development of the above axiom and its utilization in the
Speaker 1: theory of the linking of atoms, was carried out mainly
Speaker 1: by Caculae, and in the succeeding years also by Butlerrow
Speaker 1: and erlen Meyer. While the radical and type theories were
Speaker 1: attempts at securing an idea of the structure of chemical compounds,
Speaker 1: it was the valance theory which rendered it possible to
Speaker 1: furnish a lucid answer to the question as to the
Speaker 1: composition of such bodies, and especially after the year eighteen seventy,
Speaker 1: the determination of the constitution of complex molecules became the
Speaker 1: higher aim of chemistry. Some rudiments of systematic classification had
Speaker 1: before this been introduced into organic chemistry, and these classificatory
Speaker 1: beginnings were of great assistance in the erection of structural chemistry.
Speaker 1: In eighteen thirty six, Laurent, when he brought forward his
Speaker 1: nucleus series, arranged organic compounds in series. And it was
Speaker 1: in eighteen forty one that Gerhardt entered on a research
Speaker 1: to discover some general law which might suggest an all
Speaker 1: sufficing system of classification, and the following year he was
Speaker 1: ready with his letder of combustion, with its highest drung
Speaker 1: cerebral matter, its lowest carbonic acid, water and ammonia, to
Speaker 1: unfold the whole science of organic chemistry. He soon found, however,
Speaker 1: that this arrangement, according to mere complexity of composition, was
Speaker 1: no sufficient classification. So he betook himself to another line
Speaker 1: of inquiry. A note of triumph seems to ring through
Speaker 1: the following lines from the preface to his Precis de
Speaker 1: schimik Organique, published in eighteen forty four. Quote, I have
Speaker 1: succeeded in establishing homologous series. These have indicated to me
Speaker 1: the means of classifying organic substances in natural families, and
Speaker 1: of disposing them on a kind of combustion letter end.
Speaker 1: As a matter of fact, it was only the word
Speaker 1: homology that Gerhard could claim as his own. Two years earlier, J.
Speaker 1: Shield had shown that a very simple relation existed between
Speaker 1: the alcohols, then known that their radicals might all be
Speaker 1: represented by the general expression n R plus h R,
Speaker 1: suggesting the group C two H two C equal six. Moreover,
Speaker 1: in the same year, Duma had demonstrated the existence of
Speaker 1: a similar relation between the several members of the fatty
Speaker 1: acids known to him. Yet Gerr had generalized from this
Speaker 1: fact of homology and proved the possibility of predicting the
Speaker 1: existence of terms unknown in his series. Many systems of
Speaker 1: classification were suggested during the sixth decade, the classification by
Speaker 1: series as that of Shield and duma, that of series
Speaker 1: depending upon formulae, series depending upon chemical behavior, and many
Speaker 1: other systems. The lack of agreement among chemists, however, as
Speaker 1: to the formulae belonging to the different compounds, as to
Speaker 1: the relative weights of the molecules, the atomic weights, and
Speaker 1: even the number of atoms, prevented a general acceptance of
Speaker 1: any of the classifications proposed until Caculae established the fact
Speaker 1: of the tetravalance of the carbon atom, showed the difference
Speaker 1: between saturated and unsaturated compounds, and reduced his chain formulae.
Speaker 1: About eighteen sixty Franklin's views regarding a saturation capacity peculiar
Speaker 1: to the elements were accepted either delitescently or expressly by
Speaker 1: most chemists, but it was considered that this saturation capacity,
Speaker 1: under certain circumstances might be a varying one. In eighteen
Speaker 1: fifty six, Gerhardt had stated that nitrogen was sometimes triatomic
Speaker 1: and sometimes pentatomic. This view was also held by Franklin, Vts. Williamson,
Speaker 1: and Coupert, and the latter three considered that the valance
Speaker 1: was also variable in the cases of many other elements.
Speaker 1: Corbet thought that it must be assumed that a constant
Speaker 1: valancy was characteristic of a few elements, and a varying
Speaker 1: one characteristic of many more, since he perceived in it
Speaker 1: another expression for the law of multiple proportions, and nothing
Speaker 1: was known concerning the cause of valence. As early as
Speaker 1: eighteen fifty four, Colbert had concluded that each element possessed
Speaker 1: a maximum saturation capacity, but that lower stages of saturation
Speaker 1: might exist along with this, and toward the beginning of
Speaker 1: the sixties several chemists who took an active part in
Speaker 1: developing the structure theory expressed the same opinion in a
Speaker 1: more definite manner. Allenmeyer, in particular, maintained in various papers
Speaker 1: and afterward in his leabug dea organishan Kimi that each
Speaker 1: element possesses a maximum valancy, or that each is furnished
Speaker 1: with a definite number of affinivalentin or affinity points affinitetspunkten.
Speaker 1: Only part of these, however, being in many cases combined
Speaker 1: with the affinity points of other elements. Calculates theory of
Speaker 1: the constant balance of the elements could not withstand the
Speaker 1: critical examinations to which it was subjected. However, and in
Speaker 1: the course of the last forty years, the majority of
Speaker 1: chemists have adopted the view that the atoms of most
Speaker 1: of the elements possess a varying saturation capacity, varying according
Speaker 1: to the conditions. Although the structure theory was unable to
Speaker 1: accomplish the extreme expectations which aimed at a knowledge of
Speaker 1: the special arrangement of the atoms, it possessed nonetheless great
Speaker 1: practical value. The development of organic chemistry since the middle
Speaker 1: of the sixth decade shows in fact that through the
Speaker 1: aid of the structural hypothesis, the discovery of new modes
Speaker 1: of formation and decomposition of compounds, the recognition of the
Speaker 1: relations existing between various classes of bodies, and especially the
Speaker 1: interpretation of the constitution of numerous organic substances became possible.
Speaker 1: Calculates theory of the aromatic compounds forms the most striking
Speaker 1: proof of this in eighteen sixty five to eighteen sixty six.
Speaker 1: Taking the quadryvalance of carbon as his principle, Calculate called
Speaker 1: attention to the fact that in the fatty compounds, the
Speaker 1: carbon atoms are linked together by one balance of each.
Speaker 1: In the case of benzene, the next simplest assumption was
Speaker 1: made in accordance with which the carbon atoms are linked
Speaker 1: together by one and two balances alternately, so as to
Speaker 1: form a closed chain or ring. Of the twenty four
Speaker 1: affinities of the six carbon atoms, eighteen are employed in
Speaker 1: linking carbon to carbon. Thus six over two times four
Speaker 1: plus six over two times two equals eighteen. Six valencies
Speaker 1: then remain which are satisfied by the six hydrogen atoms
Speaker 1: of the benzene. Hence, according to Calculate, benzene may be
Speaker 1: represented by means of a regular hexagon whose sides are
Speaker 1: composed of single and of double lines alternately, the c
Speaker 1: groups occupying the corners. Thus, Caculae and his pupils, together
Speaker 1: with many other chemists, who had busied themselves with the
Speaker 1: derivatives of benzene after this view had been published, now
Speaker 1: directed their efforts to comparing all the known and rapidly
Speaker 1: increasing observations bearing upon this class of bodies. With the
Speaker 1: deductions drawn from the above formula and therewith to proving
Speaker 1: by actual experiment the admissibility of the assumptions on which
Speaker 1: the formula was based. The result was that Caculae's anticipations
Speaker 1: were realized and his hypothesis substantiated. In eighteen sixty six,
Speaker 1: Caculae had stated that what is wanted is that the
Speaker 1: largest possible number of substitution products of benzene should be
Speaker 1: prepared by the most diverse methods, that they should be
Speaker 1: most carefully compared with regard to isomerism, that the modifications
Speaker 1: so found should be counted end quote. And in the
Speaker 1: eighteen sixty seven edition of his textbook he called attention
Speaker 1: to a number of cases of isomerism which at that
Speaker 1: time had received no explanation. Among these we find that
Speaker 1: of ethylene chloride with ethylidne chloride, of acetyl with diethyl
Speaker 1: glycol for malaic and fiumaric for ucake and saccharic acids.
Speaker 1: The last effort of his philosophy had only found him
Speaker 1: the two formula C four H two double prime O
Speaker 1: two H two O two and C six H eight
Speaker 1: double prime O six H two O two, respectively. Calculae
Speaker 1: instanced two those bodies which only differed in their effect
Speaker 1: on polarized light, the tartaric, the malic and camphoric acids,
Speaker 1: and the amyl alcohols. It was owing to these cases
Speaker 1: of isomerism that structural formulae could not be assigned. In
Speaker 1: some cases, a greater number of isomeric bodies were known
Speaker 1: than could possibly be accounted for by any arrangement of
Speaker 1: the atoms in formulae upon a plane's surface, retaining, of course,
Speaker 1: the accepted views as to balance, et cetera. And since
Speaker 1: these isomers differed principally in certain physical properties, they were
Speaker 1: at first termed physical isomers. The study of these resulted
Speaker 1: in the consideration of the arrangement of atoms in space,
Speaker 1: the chemistry of space, or stereochemistry, in which branch of
Speaker 1: the science an extended view of atomic grouping was essayed.
Speaker 1: Modern stereochemistry was anticipated by Emmanuel Swedenborg in seventy twenty one,
Speaker 1: when he made an attempt to explain the phenomena of
Speaker 1: chemistry and physics on geometrical principles. In his prodromus principorium
Speaker 1: rerum naturalium. Seeven novorum tentaminum, chemium at physicum, experimentalem geometric
Speaker 1: explicandi and similar beginnings were made by Johann Barcussen ten
Speaker 1: years earlier. In eighteen sixty four, Carrius, who first used
Speaker 1: the term physical isomerism, explained it as follows quote. I
Speaker 1: have tentatively expressed a view as to the cause of
Speaker 1: what I call physical isomerism. Substances which exhibit this property
Speaker 1: yield under the same or nearly the same conditions, products
Speaker 1: which are either identical or physically isomeric. According to our
Speaker 1: present views, I think it improbable that such substances should
Speaker 1: have their atoms differently arranged, that is, that they should
Speaker 1: be metameric. But it is quite conceivable that in the
Speaker 1: formation of physical isomers, differences of condition may cause the
Speaker 1: production of substances with the same arrangement of the atoms
Speaker 1: within the molecule, but with a different aggregation of these molecules,
Speaker 1: and that thereon depends the difference in their properties. Thus
Speaker 1: we must consider as certainly only physically isomeric, a large
Speaker 1: number of the substances distinguished by the difference of their
Speaker 1: action on polarized light, such as the two modifications of
Speaker 1: amyl alcohol, the tartaric acids, the malic acids, et cetera.
Speaker 1: End this explanation was inadequate, and in eighteen seventy three
Speaker 1: Johannes Vivalentius eighteen thirty five to nineteen oh two, who
Speaker 1: succeeded Colbert as professor of chemistry at Leipzig in eighteen
Speaker 1: eighty five, suggested the substitution of the term geometrical isomerism
Speaker 1: for physical isomerism. He had been engaged in an investigation
Speaker 1: of the various modifications of lactic acid, and had found
Speaker 1: that the ethylene lactic acid or hydrocrylic acid prepared by
Speaker 1: Bielstein by treating beta iodopropionic acid with silver oxide, possessed
Speaker 1: properties different from those of the ethylene lactic acid obtained
Speaker 1: from ethylene cyane hydrone. This difference was so marked that
Speaker 1: he thought it might be explained by assigning the two
Speaker 1: acids different structural formulae. The first was optically inactive, while
Speaker 1: the second, paralactic acid, was textra rotary. This one point
Speaker 1: of difference appeared hardly sufficient to make it necessary to
Speaker 1: assign to paralactic acid a structural formula other than that
Speaker 1: of fermentation lactic acid. It seemed much more likely that here,
Speaker 1: at any rate, were cases of what Carriers had called
Speaker 1: physical but what Wislicenus now proposed to call geometrical isomerism.
Speaker 1: He said, quote my conclusion for the present is to
Speaker 1: declare paralactic acid and the fermentation lactic acid as most
Speaker 1: probably only geometrically isomeric. Their great similarity, even identity in
Speaker 1: all chemical properties, the ease of transformation on heating of
Speaker 1: the first into the second, and their differences, particularly in
Speaker 1: optical behavior, may all alike be explained on this basis.
Speaker 1: Concerning the special how of this explanation, I am engaged
Speaker 1: in experimental investigations. The next year ja fand Hoff furnished
Speaker 1: an answer to this. However, before giving his exposition, mention
Speaker 1: must be made of Luis Pasteurs eighteen twenty two to
Speaker 1: eighteen ninety five, pioneer work in this field. Pasta studied
Speaker 1: the various tartrates crystallographically and showed that there are four
Speaker 1: isomeric tartaric acids, that is, rhsemic acid, inactive tartaric acid,
Speaker 1: and right and left rotating tartaric acids. He showed moreover
Speaker 1: that the two latter acids crystallized in similar but in
Speaker 1: oppositely built up and antiomorph forms, that they both rotate
Speaker 1: a ray of polarized light through equal angles but in
Speaker 1: opposite senses, and that when mixed in equal quantities, they
Speaker 1: yield optically inactive rhsemic acid. Further, he succeeded in decomposing
Speaker 1: rhsemic acid again into the two optically active tartaric acids
Speaker 1: by three different methods. Pasta established the correlation of molecul
Speaker 1: ll dysymmetry and rotary power in these investigations, and it
Speaker 1: remained to discover under which conditions the dysymmetry could obtain
Speaker 1: in two molecules structurally identical. This was undertaken in eighteen
Speaker 1: seventy four by J. A. Fantauff in Holland and J. A.
Speaker 1: Lebel in France, who, in papers published that year, offered
Speaker 1: an explanation practically the same for cases of isomerism which
Speaker 1: could not be included under the theories of the time.
Speaker 1: Fantauff states that in general Lebel's original paper and his
Speaker 1: were in accord, but that while Paste's researches formed Lebel's
Speaker 1: starting point he took for his own caculaise laws of
Speaker 1: the tetravealence of carbon, to which he added the hypothesis
Speaker 1: that the four balancies are directed toward the corners of
Speaker 1: the tetrahedron, in the center of which is the carbon atom.
Speaker 1: To quote from Foynd's study of chemical composition quote font
Speaker 1: Hoff introduced no fundamental change in or addition to the
Speaker 1: original Valiancy hypothesis. A two dimensional representation of molecular structure
Speaker 1: could not at any time have been considered as really
Speaker 1: true to the actual occurrence, but it was legitimate to
Speaker 1: use it because of its greater simplicity, as long as
Speaker 1: it proved adequate to the purpose. And with this recognition
Speaker 1: and restriction, we continue to use plain structural formulae in
Speaker 1: the majority of cases. End font Hoff. Following up the
Speaker 1: suggestion that may be found implied in Pastor's paper and
Speaker 1: that was explicitly stated by Weslycenius, introduces into the science
Speaker 1: the consideration of the arrangement of atoms in space. Quote.
Speaker 1: Stereochemistry from stereos solid in the restricted sense of the word,
Speaker 1: comprises chemical phenomena which demand a considerate of the grouping
Speaker 1: of atoms in space end quote. Carbon compounds only were
Speaker 1: considered at first, but the scope of the phenomena dealt
Speaker 1: with has been extended and now includes compounds of tribalent
Speaker 1: and pentavalent, nitrogen, of tin, and of sulfur. Font Hoff's
Speaker 1: theory of the asymmetric carbon atom, however, met with difficulties
Speaker 1: on its annunciation. To quote from F. P. Armitage's History
Speaker 1: of Chemistry quote, When Fantoff enunciated his theory of the
Speaker 1: asymmetric carbon atom, he was able to say, with much
Speaker 1: show of truth, that all optically active substances did contain
Speaker 1: certainly one such atom. Soon, however, were heard dissentient voices.
Speaker 1: What of propyle alcohol, asked one, and of styrolene, demanded another.
Speaker 1: The propyle alcohol owes its activity to pis of amyl alcohol,
Speaker 1: answered Henniger. The styrrolene is impure, said fant Hoff, and
Speaker 1: their evidence was irrefutable. But font Hoff could not, in
Speaker 1: eighteen seventy four maintain that the presence of one asymmetric
Speaker 1: carbon atom necessarily implied optical activity for secondary amyl alcohol
Speaker 1: and its derivatives, also propylene alcohol, were certainly inactive, yet
Speaker 1: all contained an asymmetric carbon atom. The problem, said the stereochemists,
Speaker 1: were somewhat similar to that of the relation between tartaric
Speaker 1: and drassemic acid, so happily solved years before by Pasteur.
Speaker 1: His methods were recalled, and le Bell soon showed that
Speaker 1: these inactive bodies were in reality mixtures of two optically
Speaker 1: opposite isomers, and others helping that indeed, every substance with
Speaker 1: but one asymmetric carbon atom was equally capable of mesotomis.
Speaker 1: The four varieties of tartaric acid had offered no difficulty
Speaker 1: with two asymmetric carbon atoms similarly habited, there was necessarily
Speaker 1: neutralization or a duplication of optical activity. But where two
Speaker 1: or more carbon atoms occurred asymmetric by union with different radicals,
Speaker 1: as in the sugars and their derivatives, many more cases
Speaker 1: of physical isomerism suggested themselves and have since been verified
Speaker 1: without doubt. The asymmetric carbon atom has made a triumphant progress,
Speaker 1: winning for Lebel the JACA price of eighteen eighty one,
Speaker 1: for Fantoefe dominant voice, and the scientific councils of the world.
Speaker 1: It will rank with the phlogiston of Starr. The oxygen
Speaker 1: of La Boisier, the atom of Dalton, and the dualism
Speaker 1: of Beerzalius. Among the most noted workers in the field
Speaker 1: of stereochemistry have been Aphon Baya, Ballach, Victor Maya, Rique
Speaker 1: bischof Werner, Hantsch, Hours and Overton. Even now, the subject
Speaker 1: is in its infancy, and stereochemical theories are as yet
Speaker 1: insufficiently advanced to present a clear view of the question
Speaker 1: of geometrical isomerism. Yet, as Ladenburg has said quote, it
Speaker 1: is beyond doubt that the founding and development of stereochemistry,
Speaker 1: a name which originated with Victor Maya, is the most
Speaker 1: important thing that was accomplished in organic chemistry during the
Speaker 1: last two decades of the nineteenth century. Stereochemistry possesses a
Speaker 1: significance for this period similar to that which the foundation
Speaker 1: and introduction of the theory of aromatic compounds possessed for
Speaker 1: the twenty years preceding end end of section seventeen