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On the Polymorphism and the Enthalpies of Phase Transition of 1-Decanol 1-Dodecanol 1-Tetradecanol 1-Hexadecanol and 1-Octadecanol.

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The Polymorphkm and the Enthalpies of Phase Transition of Some Alkanols
I ,2-Dihydro-4-hydroxy-1-methyl-3-phenylsulfonyl-2-chinolon
Aus2bnachAAVZ. FastfarbloseNadeln, Schmp.: 214 - 216°(Lit.4):212 -214") (EtOH). Ausb.: 42
%d.Th.-IR(KBr): 1120, 1320(SO,), 1615(C=C), 1640cm-'(Lactam).-UV(MeOH)l,,,, (log€)
= 231 (4.61). 282 (4.10),290 (4.07), 335nm (3.69). - 'H-NMR ([D6]DMSO) 8 (ppm) = 3.43 (s, 3H,
(315.4) Ber. C60.9 H 4.15 N4.4 Gef. C60.7 H4.00
CH,), 7.2 8.2(m,9H, aromat.). -C&,,NO,S
N 4.4 Mo1.-Masse 315 (ms).
I -Ethyl-I,2-dihydro-4-hydroxy-3-phenylsulfonyl-2-chinolon
Aus 2c nach AAVZ. Fast farblose Kristalle, Schmp.: 209- 211" (EtOH). Ausb.: 36 % d.Th. - IR
(KBr): 1125,1320 (SO,), 1610( C = C ) , 1630cm-' (Lactam). - UV (MeOH) Lmax
(log E) = 235 (4.57).
282 (4.06), 292 (4.04). 337 nm (3.66). - 'H-NMR ([D,]DMSO) 8 (ppm) = 1.09 (t. 3H, CH,, J = 7),
Gef. C 62.0 H 4.48 N 4.3 Mo1.-Masse 329 (ms).
16. Mitt.: K. Gdrlitzer und E. Engler, Arch. Pharm. (Weinheim) 313, 557 (1980).
Teil der geplanten Dissertation J . Weber, Freie Universitiit Berlin.
K. Gorlitzer und J. Weber, Arch. Pharm. (Weinheim) 314, 76 (1981).
G.M. Coppola und G.E. Hardtmann, J. Heterocycl. Chem. 16, 1605 (1979).
K. Gorlitzer und J. Weber, Arch. Pharm. (Weinheim) 313, 27 (1980).
[Ph 2741
K u r dtteilungen
On the Polymorphism and the Enthalpies of Phase Transition of
1-Decanol, 1-Dodecanol, 1-Tetradecanol, 1-Hexadecanol and
Cornelis Mosselman
Department of Physical Chemistry of the Free University, de Boelelaan 1083, 1081 HV
Amsterdam, The Netherlands.
Eingegangen am 3. November 1980
The polymorphism, the melting and solid transition temperatures, and the associated
enthalpy changes of the long-chain, normal primary alkanols have been a source of
controversy for many decades. In 1974, my group published an elaborate study') in which
were suggested possible origins of the discrepancies and much new experimental material
was given. The study treated 1-tridecanol up to and including 1-hexadecanol
Recently I found a study from 1978 by Th. Eckert and J. Muller (E. and M.)2) on the
enthalpies of fusion of a series of alkanols, which included two of the members studied by
036%233/81/OMLUL279 S 02.5010
Q Vcrleg Chcmic, GmbH. Wcinheim 1981
Arch. Pharm.
us, C,, and C16.Much to my surprise, those authors stated, in summarizing the situation up
to the moment of their publication, only that the "large differences in the literature data
originated mainly from the use of different and partly obsolete methods of measurement".
They did not show to be aware of the progress made in the last two decades. Thus, for
instance, they presented enthalpies of melting without making reference to the
long-known fact that the compounds exhibit polymorphism. Therefore, it is unknown to
which polymorph the enthalpy changes measured by them pertain. However, there is
E. and M.') studied the even members from C,, up to and including C18. Of the even
members, we studied only C1, and CI6.However, our criticism on their general procedure,
together with the literature (for a review, see')) will make the reader suspicious of their
work on C,,, C,, and CI8as well.
I have refrained from giving references for every single statement in this article. The
reader is referred to my original publication') and to its extensive literature list.
a. Thermal pretreatment of the solids. E. and M. made their solids C,,, C,, and CI4go
through a thermal history, prior to melting, consisting of cooling to a few tens of Kelvin
below their melting points and annealing for five minutes. The question is, whether a given
thermal treatment, if applied to a pure sample (see however point b. about purity) allows
to ascribe the measured enthalpy of fusion to a particular polymorph. This is not the case.
The solid-solid transformations for long-chain compounds are often slow, and the different
solid phases can coexist for hours and longer.
C,, and C,, received no thermal treatment at the laboratory at all. Since the enthalpies of
melting of different polymorphs of C,, and c16 differ by several kJ to several tens of kJ'),
there is no basis for E. and M.'s statement that the enthalpies of melting they give are
accurate to 1.2-1.9 per cent (0.4 kJ mol-' (Clo)- 1.3kJ mol-' (C18).In fact, their figuresfor
C14 and c,6 differ by several kJ or more from those of any well identified polymorph of
these compounds. Therefore, not even a tentative identification of E. and M.'s materials
with one of those polymorphs is possible.
b. The effect of organic impurities and of water. E . and M . used samples with up to 0.5
per cent impurity. Even so small an amount of impurity tends to kinetic andor to
thermodynamic stabilization of phases that are thermodynamically unstable in the pure
compound. The identity of the impurity also plays a role.
E. and M . manipulated some of the liquids in air. These substances are very hygroscopic.
E. and M . did not dry the compounds, nor did they determine their water content. Besides
complicating the polymorphic relationships, moisture also can lower the enthalpies of
melting by at least several kJ3).The trend of E. and M.'s figures being much lower than ours
for our stable phases is consistent with this view.
c. Finally, their conclusions drawn from the apparent parallelism of the melting entropy
versus carbon number graphs for alkanes and alkanols are void. The even numbered
alkanes C,,-C,, are all triclinic up to their melting points4)but the alkanols, when pure, do
not constitute a uniform structure group. I t contains members having structures with
tilted chains and members having structures with vertical chains at the final melting point.
So, in trying to establish a common melting entropy increment for the members of this
Schmelzenihalpie von Fetialkoholen
alkanol group, one must make sure that the calculations pertain to a group of members
with one structure only. E. and M. did not d o this.
For readers interested in more detail about the thermal properties of the alkanols
C,,-C,, than is given in'), the material of) is available on request.
C. Mosselman, J . Mourik and H. Dekker, J . Chem. Thermodyn. 6, 477 (1974)
Th. Eckert and J. Muller, Arch. Phann. (Weinheim) 311, 31 (1978).
C. Mosselman and H. Dekker, J. Chem. SOC.Faraday Trans. 1 71, 417 (1975).
M. Broadhurst, J. Chem. Phys. 36, 2578 (1962).
5 Dissertation C. Mosselman, Amsterdam 1973.
[KPh 1941
Zur Schmelzen thalpie und Schmelzentropie von Fettal koholen
Theodor Eckert* und Jochem Muller
lnstitut fur Phannazeutische Technologie der Universitat Munster, Hittorfstr. 58-62,
4400 Munster
Eingegangen am 24. November 1980
Mosselmun ( M . ) , der von uns3) bedauerlicherweise nicht zitiert wurde, nimmt zu der
lange bekannten und auch inder Dissertation J . M u k r ' )(Munster 1978) hinreichenddurch
Literaturangaben belegten Polymorphie von Fettalkoholen undderen Beeinflussungdurch
Verunreinigungen Stellung''. Weiterhin gehort es zum selbstverstandlichen Wissensstand,
daR unterschiedliche Modifikationen auch unterschiedliche Schmelzenthalpien aufweisen.
In diesen Punkten lauft unsere Meinungsverschiedenheit auf die Frage hinaus, wie oft man
bereits lange bekannte Erkenntnisse wiederholt.
Die von uns eingesetzten Fettalkohole hatten vor der Untersuchung mehrere Jahre in
dicht verschlossenen GefaBen gelagert. Die Messungen erfolgten unter trockenem
Stickstoff. Selbst zyklisch durchgefiihrte Heiz- und Kuhlmessungen ergaben nach Lage
und Umfang weitgehend die gleichen Effekte')3).Aus den wiedergegebenen, nach
Durchschmelzen aufgenommenen DSC-Kuhlthermogrammen') ergibt sich in Verbindung
mit den Heiz-'l-hermogrammen, daB das Schmelzen von y- bzw. 0-Modifikationen registriert
wird. Die y-Modifikation bzw. die p-Modifikation (C,,,,C l r )stellt die jeweils weitgehend bei
allen Temperaturen bis zum Durchschmelzen stabilste Kristallform dar4). Die Linearitat
und die Parallelitat der von M. fur die Verbindungen C,,, CI4 und C,, angegebenen
Schmelzenthalpien der y-Modifikation5),die sich von denen der angegebenen p-Modifikationen nur wenig unterscheiden, mit den von uns gefundenen Werten sind ein Hinweis
darauf, daB es sich urn die gleichen Kristallformen handelt. Die noch verbleibende
Diskrepanz von maximal ca. 5 kJ mol-' geht vermutlich auf die grobere Reinheit der von
M. untersuchten Homologen zuruck.
o ~ ~ ~ m ~ i r n s3m0.3m~ ~ 1
Q Vcrlag Chemie. GmhH. Weinheim 1981
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enthalpies, polymorphism, hexadecan, octadecane, tetradecane, dodecanoyl, transitional, phase, decanol
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