close

Вход

Забыли?

вход по аккаунту

?

Anisotropy of Electronic and Physical Properties of Graphite and its Crystal Compounds.

код для вставкиСкачать
erate increase in hydrogen pressure to 30 atms. shortened
the hydrogenation time considerably and reduced the catalyst requirement by 30 to 50%. The results obtained in
laboratory experiments were confirmed on a factory scale.
By using pure hydrogen, still further advances in the hydrogenation of commercial oils and fatty acids may be expected.
Owing to its high carotene content, palm oil requires more
intensive d e c o l o u r i s a t i o n than is necessary for other oils
and fats. The bleachability of the raw oil is chiefly influenced
by its free fatty acid content, preoxidation, and heavy metal
contamination. The above factors can be favourably influenced by suitable control over the harvesting, recovery, storage,
Reactions with Pyrylium Salts
C6HS
I
Soluble tropocollagen has been reported to be converted into
acid and alkali insoluble collagen via a procollagen step [I].
This process is thougt to involve a nonenzymatic curing process (aggregation, chemical crosslinking) which goes on
throughout life, at later stages assuming the form of ageing.
In an investigation of this process F. Verzar (Basel) and the
author studied the different forms of collagen and the products formed in the course of its thermal contraction [2]. As
experimental material, tail tendons from rats of different ages
were used. Results: 1. Tropocollagen from 3 months old rats
contains significantly more lipophilic amino acids and less of
the amino acids characteristic of collagen than either procollagen or collagen does M, 2 During thermal shrinkage (64 "C
in water), tendons from young (7 months) and old (30 months)
animals break down into water-soluble gelatin of high molecular weight and an elastic thread; the older the animal&,
the slower the rate of degradation. However, the proportiqn
of the products of decomposition remains roughly constant
(5- 10% insoluble product in the form of the elastic thread). 3. Surprisingly, the amino acid composition of the insoluble
material, whose hydrolysis products contain increasing
amounts of amino sugars as the age of the experimental
animals increases, is similar to that of tropocollagen, particularly of its a~ component [4].
Conclusion: Collagen is not merely cross-linked tropocollagen. In the course of its development, either a chemical
transformation of the tropocollagen peptide chain or a
linking of the tropocollagen onto a second independent
collagen intermediate (pro-collagen?) must occur. The results
show how essential it is to consider the solid state of collagen in chemical investigations of this material.
[GDCh-Ortsve-band Frankfurt1Main (Germany),
May 24th, 19621.
[VB 594139 IE]
V
Isomeric 2H- and 4H-heterocyclics were also isolated in the
thiopyran series. In contrast, pyridinium salts yield with
benzylmagnesium chloride only N-Alkyl-l,4-dihydropyridine
derivatives corresponding to the 4 H-compounds, as shown
unequivocally by comparison of their absorption spectra;
these cannot be rearranged into 1,Zdihydropyridine derivatives.
A report will be published elsewhere on reactions of pyrylium
salts with methylenetriphenyl-phosphorane,which, after
addition at C-2 (or C-6), produce benzene derivatives and
which yield 1,3,4,6,8-pentaphenyl-5-benzoylazulenein an
interesting sequence of changes [4].
[Chemische Gesellschaft Karlsruhe (Germany),
May 24th, 19621
[VB 597136 IE]
[l] K. Dimroth, Angew. Chem. 72, 331 (1960).
[2] K. Dimroth and K . H . Wolf, Angew. Chem. 72,778 (1 960).
[3] H. Kroke, Ph. D. Thesis, Marburg/Lahn 1962.
[4] K. H . Wolfand K . Dimruth, unlwblished results.
462
[VB 590137 IE]
M. Brenner, Basel (Switzerland)
Pyrylium salts are oxonium-carbonium salts which are
stabilised by mesomerism as aromatic 6x cations and which
add on nucleophilic reagents at C-2, '2-6, or C-4 [I]. The site
at which primary addition occurs appears to depend on the
type of reaction involved. Detailed examination of the reaction of 2,4,6 substituted pyrylium salts with benzylmagnesium chloride showed that, in this case, primary addition
takes place at (2-4.
2,4,6-Triphenylpyrylium perchlorate (I) yields the 4H-pyran
derivative 11, which, on treatment with perchloric acid, is converted with loss of acetophenone into 1,3 diphenylnaphthalene (111) in 90 % yield [2]. Under the influence of bases, such
as CaO or preferably disodium oxydiethoxide, I1 undergoes
an ally1 rearrangement to give the 2H-pyran derivative (IV),
which under the reaction conditions is converted immediately
into 1,2,3,5-tetraphenylbenzene(V). It is possible to isolate
IV on irradiating I1 with ultraviolet light [3]. Although IV is
converted into the benzene derivative V by bases, it does not
form a naphthalene derivative 111under the influence of perchloric acid. Thus the reverse rearrangement of IV inlo 11 by
acids does not occur.
IV
Treatment of 3-pentachlorphenoxy-l,2-epoxypropanewith
adipic acid produces 3-pentachlorphenoxy-2-hydroxypropyl
mono-adipate, which possesses antibacterial and antimycotic activity and hence may be used as an additive for
dressings and bacteria- and fungus-resistant coatings.
Collagen
K. Dirnroth. MarburgILahn (Germany)
C6Hs
I
and transport of the raw oil. These investigations have
already found practical application in the Congo, where socalled 'SPB Palm Oil' is now produced, which is characterised
by first-class bleachability and, as a result, reasonably good
stability of the finished product.
[l] See, for example, E. Budecke, Angew. Chem. 72, 663 (1960).
[2] A. Meyer, Ph. D. Thesis, Universitiit Basel 1962.
[3] Compare: D.S. Jackson et al., Biochim. biophysica Acta 27,
418 (1958).
[4] K. A. Piez et al., Biochem. Biophys. Acta 53, 596 (1961).
Anisotropy of Electronic and Physical
Properties of Graphite and its Crystal Compounds
A . R . Ubbelohde, London (England)
Large single crystals of graphite for investigations of anisotropy were obtained from metallic melts, but were never quite
pure. A more suitable product was obtained by pyrolysis of
CH4 or C3Hs at 1600-2300 OC; this graphite was deposited in
the form of plates about 1 mm thick having the carbon layers
orientated parallel to the supporting surface of polycrystalline
graphite, i.e. the c-axes lie perpendicular to the support, LatAngew. Chem. internat. Edit. / Vol. I (1962) I No.8
tice defects in this pyrolytic graphite wereeliminated to a great
extent by annealing at 3000 C. Their amount at concentrations < 1 0 - 3 was determined from the Hall Effect and the
change i n conductivity in a magnetic field. Graphite almost
free from defects is bright silver i n color, but slowly darkens
on exposure t o air.
Contradictory values in the literature for the ratio pa/pc of the
s p e c i f i c r e s i s t a n c e in the directionofthea-axisandthecaxis respcictively were explained. With decreasing concenfration o f defects, pIL (ca. 10 4S1.cm) falls slightly, whilst pc,
after an iisitial rise, shows a characteristic decrease from 1 to
IO-2!l.cni i n the case ofcrystalsentirely free from defects. The
number of charge carriers is greatly influenced by the presence
of defects or foreign atoms.
Orientatcd graphite shows a positive t h e r m o e l e c t r i c
powe r alongthec-axes; i n the a-direction, theeffect iseither
slightly positive or negative depending on the concentration
of defects. This makes it possible to use orientated graphite
to construct thermo-elements capable of use up to 2400 C.
The t h e r m a l c o n d u c t i v i t y parallel to the layers is three
times that of Cu; in the c-direction i t is 0.01 times that of
Cu. The unusual anisotropy of the thermal conductivity of
pyrolytic graphite makes it possible to construct inductively
heated crucibles, which, with a wall thickness of only 3 mm.
may have a temperature of 3000 “C inside and only 2000 ’ C
on the outside.
Graphite compounds with electron donors ( e . g . CBK)or acare
SO
better
~ ) electrical conceptors ( e . g . C ~ ~ + H S O - ~ . ~ H Z
ductors than graphite, because electrons are added to an
unoccupied conductivity band, or are withdrawn from an
occupied band. The carbon layers are to be regarded a s
macro-anions or macro-cations.
[Chemische Gesellschaft zu Heidelberg (Germany),
May 28th. 19621
[VB 596134 IE]
SELECTED ABSTRACTS
A correlation between the autumnal coloration of green leaves.
and the kind and quantity of yellow coloring matter formed
in this process was established by W . Eiclienberger and C . A .
Crab on the basis of studies of the carotenoids from green,
yellowing, and yellowed leaves. Using chromatographic and
zpectroscopic methods, they found that during yellowing the
number of difl‘erent carotcnoids increases while their total
quantity decreases. When distributed between petrol ether
and methanol, the newly formed additional compounds are
found more abundantly in the upper phase (epiphase). They
exhibit. however, the same chromophoric system as the
green Icaves. New formation of carotenoids during yellowing
seems improbable. The epiphase compounds are presumably
phytoxdnthinc esters. A change in the chloroplasts and the
consequent change i n their synthetic abilities are proposed
as reasons f o r the transformation of the summer carotenoids./
[Rd 220/77 IE]
Helv. chin-,. Acta 45, 974 (1962 1 Bs.
Alkyl hydroperoxides were synthesized by G. Wilke and P .
Hein-htrch from olefins via trialkylborines. With olefins N triethylboramn gave trialkylborines which autoxidized to
R A [OOR)z; further oxidation with peracids gave compounds
of the type ROB(OOR)z, which were then hydrolyzed to the
hydroperoxides. For example, the following hydroperoxides
were thus prepared : cyclododecyl, cyclooctyl, undecyl, 2eihylhexyl, 2-phenethy1, and I - and 2-indanyl hydroperoxides. I Liebigs Ann. Chem. 652, 7 (1962) / Wi. [Rd 217/76 IE]
failed to reveal tissue deposits or secondary tissue reactions.
The time of retention in the body (as determined by testing
the urinary excretion of hydroxyproline, of which Haemaccel
contains approx. 1.5 %) depends o n the species investigated.
The half-life in the serum of rats and dogs is 4---5hours, only
5-10 7; remaining after 24 hours; in man, 74 ”/, of any
Haemaccel administered is excreted in the urine in four days.
Haemaccel meets all the requirements for a good plasma
expander, namely, adequate retention before decomposition
or excretion by the organism, the absence of antigenic or
pyrogenic properties or of effects o n serological reactions,
and compatibility with whole and citrated blood. 1 Arznei[Rd 223’80 IE]
mittelforsch. 12, 380 (1962) / --De.
A series of new, aromatically substituted, mostly sulfurcontaining mono- and diepoxides, e. g. di-(4-epoxyethylphenyl)sulfide, were obtained by H . Hopffand R . Wundeler from the
also previously unknown chlorohydrins. The compounds exhibited variable stability, as is typical of epoxides. Particularly
unstable products were obtained (in a n analytically pure
state) directly from carefully purified chlorohydrins. On
heating t o 100°C in 50 ”/, aqueous sulfuric acid, 4-epoxyethylphenyl phenyl sulfide ( I ) gave, among other products, a
dimer which was assigned the dioxan structure 11.
I
The pharmacological properties of Haemaccel, a new colloidal
plasma substitute, have been investigated by R. Muschuweck
and W. Benoit. Animal experiments have shown that Haemsolution of a polymerized gelatin hydrolyac.c-el. ii 3.5
zate w i t h added electrolytes, is tolerable as a plasma expander
and can replace 70 80 I;:, of the circulating blood plasma in
rats without i l l effect. N o disturbances in circulatory or
renal functions were observed. Histological examination
:<
Fusing I with hexamethylenediamine or phthalic anhydride
gave polyadducts which were, however, not homogeneous
because of the high n-elting points and the high rate of
reaction. / Helv. chim. Acta45,982 (1962) / Bs. [Rd 222/781E]
BOOK REVIEWS
Gmelins Handbueh der anorganischen Chemie (Gmelin’s Handbook of Inorganic Chemistry), 8th completely new edition.
Published by the Gmelin-Institut fur Anorganische Chemie
und Grenzgebiete in der Max-Planck-Gesellschaft zur Forderung der Wissenschaften. Begun by R . J. Meyer, continued by Ericli Pietsch. Verlag Chemie, GmbH., Weinheim/Bergstr. (Germany).
System No. 5 : Fluorine. Supplement Volume, 1959, XVIII, 258
pages with 31 illustrations, German-English table of conAngew. Chem. internut. Edit. / Vol. 1 (1962) / No. 8
tents, English headings and subheadings on the margins of
the text, paperbound D M 162.-- ($ 40.50), clothbound DM
167.- ($ 42.-). Edited by A . Hirsch, A . Kunze, W. Lippert,
W . Muller, Gertrud Pietsch Wilcke, F. Seuferling, L. Thaler,
and Hildegard Wendt.
The supplementary volume o n fluorine (dedicated on the
occasion of his 80th birthday to Prof. Dr. Otto Hahn, then
president of the Max Planck Gesellschaft) IS a continuation
of the main volume o n fluorine (which appeared 36 years ago
463
Документ
Категория
Без категории
Просмотров
0
Размер файла
252 Кб
Теги
physical, crystals, graphite, properties, compounds, electronica, anisotropic
1/--страниц
Пожаловаться на содержимое документа