ORGANIC CHEMISTRY
`An Advanced Treatise
`
`EDITORIAL BOARD
`HENRY GILMAN, Editor-in-Chief
`HA.NS T. CLARKE
`ROGER An.AMS
`Hoin:m ADKINS
`0.AltL S. MARVEL
`FRANK C. WmTMORE
`
`CONTRIBUTORS
`Other than the Members of the Board
`c. F. H. ALLEN
`L. F. FmsER
`A. L. RAYMOND·
`w. E. BAClllUNN
`R. 0. FusoN
`R. L. SHRINER
`L. SMALL
`A. L. HENNE
`H. A. BEATTY
`E. HEUSER
`C. C. STEELE
`A.H. BLATT
`E. C. HORNING
`W. H. SxRAIN
`G. 0ALINGAERT
`E. s. WALLIS
`J. R. JOHNSON
`R. CONNOR
`J. A. LEERMAKERS
`A. WEISSBERGER
`A.H. CORWIN
`M. L. WOLF.ROM
`IC P. LINK
`G. EGLOFF
`L. PAULING
`
`IN TWO VOLUMES
`
`VOLUME II
`
`SECOND EDITION
`Seventh Printing
`
`NEW YORK
`JOHN WILEY & SONS, INco
`LONDON: CHAPMAN & HALL, LIMITED
`
`FINCHIMICA EXHIBIT 2024
`ADAMA MAKHTESHIM v. FINCHIMICA
`CASE IPR2016-00577
`
`

`
`.,.,,. _ _ . . , . - - - • - - - -~~ ,W t l f~Y .. "Nl~\t....,_l<"_,., .. _... •• , .... ,.,,.,,_,,~,,•,.,,..,,,.,r'""
`
`COPYRIGHT, 1938J 1943
`BY
`}!ENRY GILMAN
`
`All Rights Rcse-tved.
`This book or any part U1i:reo/ mus/ ,wt
`be reproduced in any form witlwul
`the wrillen permission of the publi~her.
`
`SECOND EDITION
`Seventh Prinlin{J, November, 1050
`
`PRINTED IN THE UNIT~D STATES OF AMERICA
`
`

`
`PREFACE TO THE SECOND EDITION
`
`The purpose, plan, and scope of this treatise are given in the accom(cid:173)
`panying preface to the first edition.
`This second edition, which represents a significant expansion of the
`fhst1 contains twenty-six chapters, of which the following eight are new:
`the reactions of aliphatic hydrocarbons; synthetic polymers; catalytic
`hydrogenation and hydrogenolysis; organic sulfur compounds; aliphatic
`fluorides; the chemistry of the porphyrins; chlorophyll; and the redis(cid:173)
`tribution reaction. All the chapters carried over from the first edition
`have been revised. In some chapters the literature has been reviewed
`up to September, 1942.
`Co1Tections and suggestions will again be cordial).y welcomed. The
`editors al'e grateful to many friends for the examination of the manu(cid:173)
`scripts. Particular thanks are due to Messrs. R. K. Abbott, R. W.
`Leeper, D. 8. Melstrom, G. J. O'Donnell, S. M. Spatz, J. R. Thirtle, and
`L.A. Woods.
`
`H. G.
`
`AMES, IowA
`October, 191,2
`
`

`
`1726
`
`ORGANIC CHEl\ilSTRY
`
`tions in which these imposed influences can be neglected. This is some(cid:173)
`times achieved by extrapolation to limiting conditions, and sometimes
`by combining the analysis of mensurement.s of several properties into a
`function whfoh is independent of the experimental conditions and more
`suitable for treatment. Furthermore, a study of the van der Wanls
`equation shows that substances at the critical points of pressure., tem(cid:173)
`perature, and volume or at equal fractions of them are in corresponding
`stales, and suitable for comparison.
`As mentioned above, it is sometimes advantageous1 in order to obtain
`information about the constitution of compounds from their physical
`properties, to derive from the measured data certain functions like molec(cid:173)
`ular refraction, dipole moment, and parachor. This lends to another
`classification of physical properties into these derived, secondary ones,
`and into the directly measured prirnary data like melting point, refrac(cid:173)
`tive index, nnd dielectric constant.
`It will not be possible in this chapter to discuss at length the experi(cid:173)
`mental and theoretical background of the physical properties under con(cid:173)
`sideration. It will be shown, however, for each property, whether it is
`directly measured or derived, and if derived, from what directly meas-
`ured data.
`·
`The connection between a physical property and the constitution of
`compounds is usually established by the breaking up of the numerical
`vAlues of the physical property into values of the structural units which
`compose the molecules, of atoms nnd groups, linkages, and other con(cid:173)
`stitutive elements. This analysis may be achieved by inductive or by
`deductiV'e methods. In the fast case, a number of known compounds is
`submitted to measurements and the results are analyzed. In the second,
`fundamental theoretical deliberations lend to an understanding of the
`In.
`experimental datn in terms of the constitution of the compounds.
`the practical cases where physical properties are corl'elated 1\ith con-.\
`stitution, usually a combination of both methods is used.
`··/
`The properties which nre considered in the following first group are j
`determined by measurements of weight, volume, tempel'ature, smface 'j
`tension, and viscosity. The second group of properties discussed are :;i~
`those which are determined by the observation of their behavior toward )f
`. \?'
`electromagnetic waves and electrons.
`With rarn exceptions, all these measurements are made without the.}!
`destruction of the substances investigated. The determinations, how<}
`ever, which are the basis for the thermodynamic properties to be con-';}
`sidered in the last section, frequently involve irreversible chemica('.
`changes.
`·
`
`

`
`CONSTITUTION AND PHYSICAL PROPERTIES
`
`1727
`
`MELTING POINTS AND BOILING POINTS
`The melting point tz is characteristic for Cl'ystals. It is the temper(cid:173)
`ature at which the thermal agitation of the units composing the crystal
`lattice becomes so great that the lattice collapses. The heat which is
`absorbed in the transition is the la.tent heat of fusion. The melting
`point rises 1vith increa..~g stI·ength of the intermoleuular forces and,
`therefore, with the closeness of the packing of the atoms or atom groups.
`It also varies with the type of the crystal lattice. These three factors(cid:173)
`intermolecular forces, shape of the molecules, and type of the lattice(cid:173)
`are interdependent. Organic molecules in many cases are flexible about
`the single bonds through torsion. They will assume certain configw·a(cid:173)
`tions according to the forces impressed upon them, and vice 17ersa, and
`the crystal lattice depends on the shape of the molecules and on the
`electric fields. Often more than one crystal form repref3enting a.n energy
`minimum is possible: polymorphism. Greater symmetry and rigidity of
`the molecule increase the amount of energy necessary to produce a dis(cid:173)
`turbance through which the lattice collapses; e.g., the melting point of
`furnario acid is higher than that of maleic acid, and the melting point
`of succinio acid lies between the two. This summary shows not only
`that constitutive factors hn. ve ample chance to influence the melting
`point, but also that their influence is manifold and complex, so that no
`general simple rules may be expected.
`Franchimont, Eykma.n, and van der Kam 13 found that the melting
`points of organic compounds rise when two H-atom.s bound to the same
`C-atom are replaced by an 0-atom, or one H-atom is replaced by an
`OH or J\1H2 group, and that the melting points are lowered by replacing
`H which is bound to oxygen or nitrogen by CH3. These variations are
`1·ea.dily understood on the basis of the above general statements; the
`melting points 1·ise with the introduction of more polarizable atoms ani
`· an increased opportunity for hydrogen bond formation. For the same
`reason, compounds with normal chains have, in general1 higher melting
`points than the isomers with branched chains; the shape of the former
`gives more opportunity for H , H attractions, which are a source of
`intermolecular forces.
`On the other band, branched molecules of high synunetry-globufo.r
`molecules-may have exceptionally high melting points; thus, hexn.(cid:173)
`methy1eth:me melts at 104 ° C., and n-octane at -56.5 ° C. Timmer(cid:173)
`mans 14 has drawn attention to this phenomenon and suggested that
`l:! Timmermans, lnBt. intern. chim. Solray, 4. 191 {1931).
`l:I van der I{n,m, Rec. tra:v. chim. 1 45, 734 (1926).
`14 Timmermans • .J. chim. phy&., 35t 331 (1938).
`
`

`
`1728
`
`ORGANIC CHEMISTRY
`
`globular molecules absorb a considerable amount of energy as rotational
`energy without causing a collapse of the crystal lattice. Below the
`melting point, such substances in the solid state undergo a transforma(cid:173)
`tion which in many respects, e.g., in the specific heat and dielectric
`constant, makes them resemble liquids.
`In many homologous series, the melting points rise with increasing
`molecular weight, evidently through the greater intermolecular forces
`acting between the larger molecules. With the initial members of ho-(cid:173)
`mologous series, the addition of a CH2 group frequently lowers the
`melting point, because the interference with the forces between the
`characteristic groups, like -C02H and -OH, by the new groups is
`greater than the gain of intermolecular forces through them. In some
`series with strong forces between the characteristic groups, like the
`d.ioarboxylic acids, this lowering of the melting poin~ wit.h increasing
`molecular weight persists as a general tendency throughout the series.
`As the effects of the chains dominate those of the characteristic groups,
`the melting points of the higher members of a number of homologous
`series approach a common limit of about 120°.12• 151 16 ~owever, the
`convergence points for quite a number of series differ markedly, indi(cid:173)
`cating the importance of the characteristic groups for the packillg and
`the cohesion in the crystals, even in compounds with long chains.
`The change in the melting points of homologous series with the addi(cid:173)
`tion of CH2 is in some cases continuous, e.g., with the aliphatic alcohols,
`the ketones, and the fatty acid amides. In other series, the fatty acids,
`the normal paraffins, the dicarboxylic acid diamides, the glycols, the
`alkylmalonic acids, etc., the phenomenon called alternation or oscilla(cid:173)
`tion occurs (Fig. 1).
`C.
`1ao0---------.--...----.----i---r---,
`
`~
`
`~ 110°1----A---+-----4--,~-J..-+-~-+--t---i
`t:o .s = 0
`
`~1001--~~+->"""f+---t+~-+--i----t-~--t--~t------t
`
`801----...L----'---"---'---'-------,.,,.....---
`8 9 m ll D ~ li
`1
`4 G O 1
`~ $
`F10. 1.-Melting points of homologous malonic esters OnH2n+1CH(C02R)2.
`Verb.de nnd CooP3. Jr.i Rec. lra11. chim.t 49,568 (1930).
`(Courtesy of publishers).
`ts Timmermans, Vll Congr. intern. froid. 1936.
`16 Verkade a.nd Coops, Jr,s Rec. trav. cMm., 49. 568 (1930).
`
`

`
`CONSTITUTION AND PHYSICAL PROPERTIES
`
`1729
`
`The oscillation of physical constants, like melting point and heat of
`crystallization, n sometimes consists in the fact that., in a homologous
`series, with an increase of CH2J an increase and a decrease of the con ..
`stant in question alternate (see Figs. 1 and 5); the melting points and
`the solubility in water of the normal saturated dicarboxylic acids are
`examples of this type of oscillation. In other cases (see Fig. 2), only
`
`0,0G
`
`.€a
`~o.ot
`
`0.02
`
`Num bcr or Carbon Atoms
`Fm. 2.-Viscosity of diethyl esters of dibasic acids.
`From dat:.\ of' Ceder, Ann. Univ. Fenniccu Aboenm, Ser. A2, No. 4 (1026} (0 .• 4.., H, 3137 (1928)].
`(Courtesy oC pub!i!hcrs.)
`
`larger and smaller increases of the constants alternate with each other.
`No essential difference exists between these two types, which are called
`If the decrease or the smaller in(cid:173)
`complete and incomplete oscillation.
`crease of the constant in question occurs when passing from a member
`of the series "With an even number of carbon atoms to the next ( odd)
`term, the oscillation is called even or normal oscillation; the reverse case
`is named 'Uneven or inverse os<:illation.
`The oscillation has been interpreted as due to the facts that the
`hydrocarbon chains have a zigzag form, which was confirmed1 by x-ruy
`structme analysis, and that the more symmetrical members have a posi(cid:173)
`tive increment, the less symmetrical members a negative one. In ac(cid:173)
`cordance with this, even oscillation of the melting points is observed
`with paraffins an,d terminal dihalogenides, dihydroxides and diamines,
`the dicarbo;..·ylic acids and all their derivatives, while uneven oscillation
`occurs with alkyl monohalides, mercaptans, etc.
`Tammann, 18 on the other hand, explains the alternation by a...~uming
`that, for example, fatty acids with even carbon numbers occur in two
`polymorphic forms, while the odd-membered acids lack the higher-melt(cid:173)
`ing modification.
`Weygand and Grilntzig 19 contributed an interesting observation to
`this quest.ion. They studied homologous monoacidic triglyceiides which
`show oscillation of melting points, and found that these compounds
`
`1i Garner, J. Chem • .Soc., 2491 (1926).
`lS Tamma.nu, Z. anorg. allgem. Chem., 109, 221 (1920) ; 115, 288 (1921).
`19 W eygand nnd Grunfaig, ibid., 206, 313 (1932).
`
`

`
`1730
`
`ORGANIC CHEMISTRY
`
`exist in polymorphous modifications. The polymorphous individuals of
`the different homologs which closely resemble each other crystal-opti ...
`cally were arranged in corresponding series, and it was found that the
`melting points within these series rise continuously.
`A phenomenon of somewhat related natUl'e is the so-called pe1'i(cid:173)
`odicity. The occurrence of anomalous properties in homologous series
`at, or in the neighborhood oft the fifth (see for instance Fig. 1), tenth,
`and fifteenth members has been interpreted as indicating the an·ange(cid:173)
`ment of the carbon atoms in a chain in the form of a spiral qr helix.20
`However., there is no indication of a periodic repetition of melting-point
`miruma. Furthermore, the minima lie, with the fatty acids, at the
`compound with a butyl group; with the paraffins and primary aliphatic
`alcohols, at the member with the propyl group; with alkyl halides, at
`the ethyl halide, and in some series higher than at the five-carbon com(cid:173)
`pound.16, 20
`In the benzene series the melting points rise from the ortho to the
`meta compounds and from the meta to the para compounds if the sub(cid:173)
`stituents are of the same kind. Beacall 21 summarizes an investigation
`of the melting points of simple benzene derivatives as follows: The in(cid:173)
`troduction of a pair of chlorine or bromine atoms in para position to each
`other increases the melting point in an approximately constant ratio.
`
`TABLE IV
`
`IN".l'RODUCTION OF TWO CHLORINE A'l'OMS lN para POSITION
`
`Benzene Compound
`Benzene
`p-Dichlorobenzene
`s-Tetrachlorobenzene
`Hexachlorobenzene
`1,2,4-Trichlorobenzene
`Pentachlorobenzene
`J\i!onobro:m.obenzene
`1-Bromo-2,5-clichlorobenzene
`etc.
`
`M.P. eK.)
`278.4
`326
`410.5
`500
`289.5
`358
`242
`307
`
`Ra.tio
`
`1.17
`1.26
`1.22
`
`1.23
`
`1.27
`
`The introduction of a simple "asymmetric" halogen atom into benzene
`or asymmetric substituted halogen benzene lowers the melting point in
`an approximately constant ratio. The rule of Watt and Carnelley that,
`the more symmetrical the constitution of a benzene derivative is, the
`higher is the melting point, holds only for derivatives with substituents
`of the same kind.
`
`20 Timmermans, Bull. soc. cMm. Belg., 35, 282, 1126 (1926).
`:n Benca.ll. Rec. iTav. chim •• 471 37 (1928).
`
`

`
`CONSTITUTION AND PHYSICAL PROPERTIES
`
`1731
`
`TABLE V
`
`INTRODUCTION OF 03.\"E CHLORINE ATOM
`
`Benzene Compound
`Monochlorobenzene
`Benzene
`
`M.P. {°K.)
`228
`278.4
`
`Ratio
`
`0.82
`
`1,2,4-Trichlorobenzene
`1,4-Dichlorobenzene
`
`Pentachlorobenzene
`~-Tetrachlorobenzene
`
`1-Bromo-3,4-clichlorobenzene
`1-Bromo~4-chlorobenzene
`etc.
`
`289.5
`326
`
`358.5
`410.5
`
`297.5
`339
`
`0.89
`
`0.88
`
`0.88
`
`Formulas have been given from which melting points ean be calcu(cid:173)
`lated with reasonable accuracy.
`Austin 22 has suggested the equation
`
`logM = A +BTm
`
`where Mis the molecular weight, Tm is the melting point, and A and
`Bare constants. The constants A and Bare generally different for each
`homologous series, although the constant B, which gives the slope of
`the curve, may be the same for several different series. Thus, for
`n-hydrocarbons and n-alcohols, B has the value 0.0040, and hence the
`log bf, T,m, curves for these series have the same slope. Variatibns in the
`structures of homologous series usually produce changes in the slope of
`the curves. The curves for monosaccharides, aromatic alcohols, and
`aromatic acids have negative slopes as contrasted with the positive
`value of B found for paraffin hydrocarbons.
`King and Garner :?a observed a relation between the number of car(cid:173)
`bon atoms in a fatty acid molecule and the entropy change on crystalliza(cid:173)
`tion. They found that in acids containing more than twelve carbon
`atoms the heat of crystallization, Q, increases at the rate of 2.06 kcal.
`per g.-mol. for every two CH2 groups added. In the same selies, the
`melting points first drop to a minimum at four or five carbon atoms
`and then rise and gradually become linear. In this, as in most other
`aliphatic series, the odd and even carbon compounds form two separate
`
`::!! Austin1 J. Am. Che-m. Soc. 1 52, 1049 (1930).
`~3 King nnd Garner, J. Ch.em. Boo., 578 (1931).
`
`

`
`1732
`
`ORGANIC CHE~IISTRY
`
`series, the melting points of which eventually approach a comm.on
`curve.24 Figure 3 illustrates the data of King and Garner.
`
`M.P.
`
`4
`
`8
`
`16
`12
`Number of Carbon Atoms
`FIG. 3.-Melting point.s and heat of crystallization of n-fatty acidis.
`(Q = hen.t of crystallization in calories per mole.)
`From data of King and Gamer, J. Chem. Soc., 578 (HJ31).
`(Courtesy of publishers.)
`
`20
`
`24
`
`The heats of fusion, H, and the melting points in abqalute tempera(cid:173)
`ture, T 1 are roughly related by the Crompton-Walden rule:
`tiH T = constant
`
`At the boiling pofot under atmospheric pressure, the thermal agita(cid:173)
`tion of the particles of a liquid becomes so great that the particles leav(cid:173)
`ing the surface of the liquid exert a pressure of 1 atmosphe1·e. The
`energy absorbed in the transition to the gaseous state is the latent heat
`of vaporization. The question whether the heat of vaporization is a
`property measured under conditions suitable for comparison is answered
`by Guldberg's rule that the boiling point equals about two-thirds of the
`critical temperature. Liquids at the boiling point are therefore in cor(cid:173)
`responding states.
`:, (a) Hildebrand and Waohwr, J. Am. Chem. Soc., 51, 2487 (1929); (b) Chuit nnd
`Hausser, Hel'O. Chim. _,1.cta, 12,850 (1929); (c) Ruzicka, Bull. soc. chirn. Bdg., 41,565 (1932).
`
`

`
`CONSTITUTION AND PHYSICAL PROPERTIES
`
`1733
`
`A numerical relation between boiling point in absolute temperature,
`TBP, and latent heat of vaporization, X, is given by the Pictet-Trouton
`rule:
`
`A (in cal.) = a T BP·
`a ~ 20, except for OH-containing substances, where it is about 26.
`The rule is plausible because both boiling point and heat of vaporization
`depend on the intermolecular forces.25 The deviation of the OH-con(cid:173)
`taining compounds may be caused by hydrogen bonds.
`Of the numerous equations developed for the prediction of boiling
`points, the following expression of Nekrasov 25 may be cited 8,S an
`example:
`
`M-:Z
`TBP = I( v55
`
`Mis the molecular weight, ~ the sum of certain empirical equivalents
`given in Table VI, and Ka constant (about 29.0 for hydrocarbons).
`
`TABLE VI
`
`EQUIVALENTS FOR CALCULATION OF THE BolLING PotNTS OF ORGANIC
`COMPOUNDS (Nekrasov)
`
`C
`H
`Tert. C in ring
`Qunt. C in ring
`Double bond in
`2 rings
`Benzene ring
`
`2.0
`LO
`1.50
`1.75
`
`1.00
`1.00
`
`Each C atom more than 10
`=CH2
`-CHs on tert. C
`-CHa on quat. C
`{=0-C=
`=C=
`-CR CH-
`
`Other rings
`3 members
`4 members
`
`Sat.
`+0.75
`+0.20
`
`Unsat.
`
`+1.00
`
`5 members
`6 members
`
`Sat.
`0.00
`0.00
`
`+0.25
`+0.25
`+0.25
`+0.60
`-0.50
`-1.75
`-0.75
`
`Unsat.
`+0.50
`0.00
`
`The calculation of the boiling point of ethane will serve as an example
`of the use of the data in Table VI. Ethane has 2 carbon atoms and 6
`hydrogen atoms; the value of :Z is equal to 2 X 2 + 6 X 1 = 10.
`If
`the value 29.0 is used for J{, TBP is calculated to be 183°. The boiling
`. point of ethane is observed to be 185_° K.
`The simpler formula 27 is applicable with non-polar compounds.
`K:i\f%
`TBp=~
`
`!!$ Landoni Z. phy8i1;,. Ohe;m.., B11 1 24:2 (1930); Hirschfelder and Eyring, J. Phys. Chem.
`41, 249 (1937).
`tG NekrasoY, z. physik. Chem., A141, 378 (1929).
`n Nel..~nsov, ibid •• AUS. 216 (1930).
`
`

`
`1734
`
`ORGANIC CHEMISTRY
`
`According to van Arkel, 28 the boiling points of non-polar compoUrnds
`can be computed for molecules containing only carbon and halogen, by
`means of the formula
`
`_ (V -
`T
`BP -
`
`'Vc)2
`V
`
`I{
`·
`a
`
`V is the molecular volume, V c the atomic volume of carbon, and
`Ka is a constant involving the a of van der Waals equation. The
`square root of a exhibits additive characteristics and can be calculated
`from atomic values. sa. Table VII shows comparisons of calculated and
`observed boiling points. The data of Table VII establish the general
`
`TABLE VII
`
`VF= 11.0
`
`Bou.,ING PoINTs CALCULATED FROM ATOMIC VoLUMES
`V1 = 39.6
`V01 = 22.8
`V»r = 29.1
`Ve= 11
`TBP (calc.) Tnp (observed)
`V
`Compound
`127.4
`CBr4
`462°
`465°
`433
`121.1
`428
`CClBr3
`114.8
`CCI2Br2
`408
`406
`377
`108.5
`CC13Br
`375
`102.2
`CCI.1
`349
`349
`90.4
`298
`298
`CClaF
`249
`78.6
`CCbF2
`248
`380
`109.3
`380
`CBr3F
`298
`300
`91.2
`CBr2F2
`143
`150
`55
`CF4
`415
`419
`119
`CCI3I
`126.8
`CClBr=CCIBr
`445
`446
`392
`394
`114.2
`CCl2-CClz
`
`reliability of the method of calculation for non-polar or only slightly polar
`compounds.
`More recently, Egloff, Sherman, and Dull 29 have given the equation
`T = a log (n + b) + k
`
`where T is the boiling point in degrees absolute; n is the number of ear ...
`bon atoms in the molecule; a, b, and k are empirical constants.
`\Vb.en
`these were evaluated from the boiling points of the normal alka.nes and
`the observed boiling points were compared with those calculated accord(cid:173)
`ing to the formula abovei very good agreement was obtained} as shown
`in Table VIII.
`28 van .Arkel, Rec. trav. ckim., 51, 1081 (1932); 62, 719, 733 (1933) ; 53t 91, 246 (1934)
`!!9 Egloff, Sherman, n.nd Dull, J, Phys. Chem., 44, 730 (1940).
`
`,;
`
`

`
`CONSTITUTION AND PHYSICAL PROPERTIES
`
`1735
`
`TABLE VIII
`NORMAL ALK.A1'"ES
`T ::; 745. 42 log (n + 4.4) - 416.31
`T
`(Observed)
`OK.
`(111. 55)
`184.6
`230.9
`272.6
`309.08
`
`Number of
`Carbon Atoms
`(1)
`2
`3
`4
`5
`
`T
`(Calculated)
`oK.
`(129.63)
`184.6·
`231.6
`272.7
`309.08
`
`6
`7
`8
`9
`10
`
`11
`12
`13
`14
`15
`
`16
`17
`18
`19
`
`341.88
`371.53
`398.88
`423.83
`447.1
`
`468.9
`489.3
`507
`524
`543.6
`
`560.6
`576
`590.0
`603.1
`
`341.80
`371.52
`398.75
`423.85
`447.2
`
`468.9
`489.3
`508.4
`526.5
`543.6
`
`559.9
`575.4
`590.2
`604.3
`
`oT
`ox.
`(-18.08)
`0.0
`-0.7
`-0.1
`0.0
`
`+o.os
`+0.01
`+0.13
`-0.02
`-0.1
`
`0.0
`· 0.0
`-1.4
`-2.5
`0.0
`
`+0.1
`+o.6
`-0.2
`-1.2
`
`Name of Compound
`(Methane)
`Et.bane
`Propane
`Butane
`Penfane
`
`Hexane
`Heptane
`Octane
`Nom:me
`Decane
`
`Undeca.ne
`Dodecane
`Tridecane
`Tetradecane
`Pentadecane
`
`Hexadecn.ne
`Heptadecane
`Octnclecane
`N onndecn.ne
`
`The paper contains a similar study of the boiling points of thirty
`additional analogous series of aliphatic hydrocarbons, the mekn devia(cid:173)
`tion between calculated and observed values being only 0.7 per cent for
`the hundred and forty-three hydrocarbons which were considered. The
`values a and b ·were universal for all these series, while k v:.uied from
`series to series. Generalizations are given on the effect on boiling point
`of the structUl'es of the hydrocarbons of the different series. For in ...
`stance, in the straight-chain molecules, a double bond in the terminal
`position lowers the boiling points (relative to the normal alkanes) by
`5° to 6°, a double bond in the 2-position (cis- and tran~-2-alkenes) lowers
`the boiling point less than 0.5°, while the presence 0£ a triple bond in the
`terminal position raises the boiling point about 2.5°.
`\Vb.en the boiling points of polar compounds are calculated according
`to van Arkel's formula, there are appreciable differences between the
`observed and the calculated values. For example, the introduction of
`bromine into benzene to form bromobenzene gives an observed value
`
`

`
`1736
`ORGANIC CHE!\HSTRY
`14 ° higher than that calculated. The discrepancy is due to the polarity
`of the bromobenzene. Van Arkel has studied the relationships between
`boiling points and dipole moments in a large number of aromatic and
`aliphatic compounds and calculated dipole moments from boiling points.
`Examples of the agreement between observed and calculated moments ·
`are found in Table IX.
`
`TABLE IX
`
`DIPOLE MOMENTS CALCULATED FROM BOILING POINTS
`
`Compound
`o-Dichlorobenzene
`m-Dichlorobenzene
`p-Dichlorobenzene
`o-Nitrotoluene
`m-Nitrotoluene
`p-Nitrotoluene
`
`Moment Observed Moment Calculated
`2.24 X 10-18
`2.72 X 10-18
`1.42
`1.57
`0
`0
`3.74
`3.70
`4.20
`4.15
`4.40
`4.38
`
`B.P., °C.
`liS
`172
`171-4
`218
`230
`238
`
`The correlation of the boiling points to the factors governing the
`intermolecular forces, like dipole moments, polarizability, and presence
`of hydrogen bonds, has been presented by Hi.ickel, 3° and the following
`rules will need little explanation, because their connection with the inter(cid:173)
`molecular forces is evident.
`Of isomeric non-cyclic compounds, the one with the normal carbon
`chain always has the highest boiling point. With increasing branching
`of the chain, the boiling point falls.
`Of isomeric alcohols, halogenides, nitro compounds, etc., the primary
`compounds have the highest boiling point; the secondary have lower
`ones; and the tertiary, the lowest ones (screening of thetpolar group).
`Of isomeric bicyclfo compounds, those in which the rings are con(cid:173)
`nected by bridges (which give flexibility to the molecule) have lower
`boiling points than those with condensed 1ing systems.
`Of ms-tram isomers, the ms compound has the higher boiling point
`and the higher dipole moment.
`The bigger and more compact the substituent (screening), the more
`the approach of a substituent to a carbonyl group depresses the boiling
`point.
`Of isomers with more than one double bond, those with conjugated
`double bonds have the higher boiling points (higher polarizability of
`systems of conjugated double bonds than of isolated ones).
`A more detailed analysis of the part which the various intermolecular
`forces play in the boiling points of compounds containing one or two
`
`:so Ruckel, "Theoretische Grundlagen der organischen Chemie," Akademische Yer.
`lo.gagesellschaft, Leipzig, 1935, Vol. 2, p. 122.
`
`

`
`CONSTITUTION AND PHYSICAL PROPERTIES
`
`1737
`
`carbon atoms in combination with halogen and hydrogen has been
`given by Stevels. 31
`
`SOLUBILITY
`
`Solubility, the temperature coefficient of solubility, and the tendency
`to crystallize in and from various solvents are very important properties
`for practical work in otganic chemistry. Some generalizations which
`have been suggested by Hildebrand 32 and others couceming these prop(cid:173)
`erties may be useful, although many exceptions can be found. The
`absence of more reliable relationships between solubility and constitu(cid:173)
`tion is understandable, because the solubility depends on intermolecular
`forces (solvent/solute, solute/solute, solvent/solvent)1 the connection of
`which '\'\ith structuml elements is highly complex.
`Substances dissolve in water if they can form hydrogen bonds with
`water (such as alcohols, acids, ketones, ethers, esters, amines1 and ni(cid:173)
`triles).
`Non-electrolytes do not dissolve in water if they cannot form hydro ...
`gen bonds with water (suoh as hydrocarbons, halogen de1·ivatives,. and
`carbon disulfide).
`The solubility of hydrogen bond liquids in water and in non-hydrogen
`bond liquids depends on the number of -OH and -NH2 groups and
`the size of the hydrocarbon part of the molecule. For instance, metha(cid:173)
`nol is soluble in water but not completely miscible with heptane (at
`room temperature), while n-butyl alcohol is incompletely miscible with
`water but completely miscible with heptane.
`Relatively high solubilities of halogenated hydrocarbons and of
`acetylenic compounds in various solvents indicate tho exist~nce of
`CH~ 0 a.nd CH-~ N hydrogen bonds.33
`·
`Compounds with rigid molecules are less soluble than compounds
`wit.h flexible molecules.
`Of two solids having approximately the same heats of fusion1 the one
`having the higher melting point is less soluble in a given solvent at u
`given temperature than the one having the lower melting point.
`If two solids have equal melting points, the one '\\'it.h the greater
`heat of fusion will be less soluble in a given solvent.
`If two substances have essentially the same heat of solution, their
`solubilities in a given solvent will be in the order of their melting points.
`All normal liquids (non-hydrogen bond liquids) are miscible (unless
`
`:1 Ste\·els, Rec. tro.11. chim. 1 581 229 1 244 (1939).
`~2 Hildebrnnd 1 "Solubility.'' 2nd ed., Reinhold Publishing Corp., Nev.· York (1936).
`:13 Zellboeier1 Copley, and Marvel. J. Am. Chem. Soc., 601 1337 (1938); Copley nnd
`Rolley, ibid., 61, 1599 (1939).
`
`

`
`1738
`
`ORGANIC CHEl\USTRY
`
`their internal pressures are greatly different), since the energy change on
`mi."'<ing is very small and the entropy increases.
`A measure of the intermolecular forces mentioned above is given by
`the internal pl'essure, i.e.1 the tel'm a/1l, in the van der Waals equation,
`which makes allowance for the deficit _in the e.."-:ternal pl'essure. The
`internal pressure may be approximated by an e..xpression more con(cid:173)
`veniently measured, l/v., where l is the molecular heat of vaporization
`and vis the molecular volume.~ Substances without hydrogen bonds
`and with internal pres.gmes nearly equal are more soluble in each other
`than those the internal pressures of which differ appreciably from each
`other. The differences in solubility of a solute in a series of solvents ·will,
`therefore, be determined by the differences between the internal pres(cid:173)
`sures of the solute and the various solvents. Mortimer 34 has tabulated
`data on the solubility of p-dibromobenzene in a variety of solvents of
`different internal pressures, and it will be noted that the ideal solubility
`of 24.81 i.e., the solubility of p-dibromobenzene in pure p-dibromoben(cid:173)
`zene, is approached when the internal pressure of the solvent is nearly
`that of p-dibromobenzene. vVhen the internal pressure of the solvent
`differs greatly from that of p-dibromobenzene, the solubility of the
`latter is relatively low.
`
`TABLE X
`
`Solvent
`Hexane
`Diethyl ether
`Carbon tetrachloride
`Benzene
`p-Dibromobenzene
`Carbon disulfide
`Nitro benzene
`Aniline
`Phenol
`Ethyl Alcohol
`
`SOLUBILITY OF p-DlBROMOEENZENE
`Solubility, Moles Solute
`per Liter of Solvent
`8.6 X 10-2
`18.8
`I 19.3
`21.7
`(24.8)
`22.4
`17.4
`10.7
`4.67
`1.98
`
`Internal Pressure
`0.56
`0.62
`0.81
`0.96
`1.09
`1.18
`1.07
`1.4
`1.4
`2.9
`
`Hildebrand 35 bas pointed out that Raoult's law can sometimes be
`utilized in the determination of solubilities. Liquid substances showing
`no heats of solution or no deviations from additivity of volumes on solu(cid:173)
`tion :h1 general obey Raoult's la,v; the evolution of heat or a decrease
`of volume upon dissolving one substance in another usually indicates
`a negative deviation from the law, whereas changes in the opposite .
`direction indicate a positive deviation.
`a4 Mortimer, fbid. 1 45, 633 (1923).
`a$ Hildebrand 1 ibid., 51, 66 (1929); 37, 970 (1915).
`
`

`
`CONSTITUTION A.J.'rD PHYSICAL PROPERTIES
`
`1739
`
`SURFACE TENSION
`
`Surface tension is the tendency of a liquid to diminish its surface, t.he
`term ''surface11 meaning the interface between the liquid and its vapor
`or a different gas. It is caused by intermolecular forces and has the
`dimension dyne/ cm. The surface tension between two liquids, called
`the interfo.cial tension, is determined by the surface tension of each and
`by the attractive forces exerted between the unlike molecules.
`Thfany methods have been devised to measure the surface tension,
`for instance, by determining the weight of droplets, the rise of a liquid
`in a capillary, or the force necessary to detach a solid from the surface
`of a liquid.
`A general relationship between surface tension and temperature is
`given by Eotvos,36 and Ramsay and Shields: 37
`
`( M )'!i
`
`1 D _ d
`
`= K(Tc - T)
`
`where 'Y i5 the surface tension, M the molecular weight, D and d the
`densities of the liquid and gaseous forms of the substancesJ TO the critical
`temperature, T the temperature of observation, and J{ a constant. I(
`·usually has a ·value of about 2.1 for non-associated liquids when the
`temperature is expressed in degrees Centigrade.
`The equat.ion becomes invalid for associated liquids., in which several
`molecules of the same species