вход по аккаунту


Triphenylstannyl- and Trimethylsilyl-ethoxycarbonylcarbene from Ethyl Diazo-(triphenylstannyl)- and -(trimethylsilyl)-acetate.

код для вставкиСкачать
centrifugation, adjusted to p H = 7.2 by dilute hydrochloric
acid and placed on a column (10 cm in length, 4.5 cm in diameter) of DEAE-cellulose (DEAE-Sephadex A-25) whose
chloride form has been washed with tris[(hydroxymethyl)amino]methane/HCl buffer (PH = 7.2) until the eluate has
p H = 7.2. The column is eluted with buffer until no more
porphobilinogen is removed from it. The eluates are evaporated in a vacuum to ca. 1800 mi, then adjusted to p H = 4 by
dilute hydrochloric acid and treated with 20 % mercury(I1)
acetate solution. The resulting precipitate is centrifuged off,
washed with 1 % mercury@) acetate solution, and suspended
in ca. 3 ml. of water. H2S is passed into the suspension to decompose the mercury compound. Then the precipitate is centrifuged off, nitrogen is passed into the liquid to remove H2S,
and the p H of the liquid is adjusted to p H = 4 by dilute hydrochloric acid. This precipitates crude porphobilinogen
which is centrifuged off after having been kept for 12 h in a
refrigerator. Just sufficient 0.5 N ammonia is added to the
centrifuge tube to dissolve the porphobilinogen, undissolved
material is centrifuged off, the p H is adjusted carefully to 4
by glacial acetic acid for precipitation of the porphobilinogen,
and the whole is left overnight in a refrigerator. The crystals
are filtered off under suction and washed with ice-cold dilute
acetic acid (PH = 4) and immediately thereafter with a little
cold acetone. Drying in a vacuum desiccator gives 73 mg
(12 %) of porphobilinogen.
Received: August 1st. 1967
[Z 588 IEI
German version: Angew. Chem. 79,905 (1967)
[*] Dip1.-Chem. G. Bezold, Dr. G. Miiller, and Dr. 0. Miiller
Isotopenlaboratorium der Abteilung fur Chemie, Geologie
und Biologie der Universitat
Azenbergstrasse 14-1 6
7 Stuttgart (Germany)
[l] For a review, see J. E. Falk: Porphyrins and Metalloporphyrins. Elsevier, Amsterdam 1964.
[2] W . Walerych, Acta Biochim. Polon. 10, 243 (1963).
[3] The identity of these substances is being further investigated.
[4] K . Bernhauer, E. Becher, and G. Wilharm, Arch. Biochem.
83, 248 (1959).
[ 5 ] Biochemisches Taschenbuch. 2nd Edit. Springer-Verlag,
Heidelberg 1964, Part 2, p. 99.
161 G. H. Cookson and C. Rimington, Biochem. J. 57,476 (1954).
and (46) were obtained (in yields of 80 and 95 %, respectively)
by treating diethyl mercuribis(diazoacetate) (2) 121 in boiling
benzene for 5 and 3 h, respectively, with rather more than
one equivalent of bis(triphenylstanny1) or bis(triniethykily1)
sulfide (3). After filtration, the benzene solutions were
evaporated (aspirator vacuum) in a rotary evaporator.
+ M - S - M - H ~ SM-C-COOC,H,
Hg [C(N2)-COOC2H5]
f 3)
f 4)
la), M
ib), M
Received: August lst, 1967
[Z 589 IE]
German version: Angew. Chem. 79, 906 (1967)
[*I Prof. U. Schollkopf and Dr. N. Rieber
Organisch-Chemisches Institut der Universitlt
Windausweg 2
34 Gottingen (Germany)
[I] Conditions: Hanovia lamp 450 W, Pyrex filter, -7 "C.
[2] E. Buchner, Ber. dtsch. chem. Ges. 28, 215 (1895); cf. F. Gerhart, I/. Schollkopf, and H. Schumacher, Angew. Chem. 79, 50
(1967); Angew. Chem. internat. Edit. 6, 74 (1967).
Sulfur and Selenium Adsorbate on Platinum
Electrodes in Acid and Alkaline Electrolytes
By H. Binder, A. Kohling, and G . Sandstede [*I
Since the properties of catalysts are modified by adsorbates, it
is of interest to find out the conditions under which adsorbed
substances exist on the surface of catalysts. We have studied
the adsorption of sulfur and of selenium on platinum by the
TriphenyIstannyl- and Trimethylsilyl-ethoxycarbonylcarbene from Ethyl Diazo-(triphenylstanny1)- and -(trimethylsilyl)-acetate
By U. Schollkopf and N. Rieber [*I
Unusual properties are to be expected for metalated carbenes
because the empty or filled electron orbitals of the metal may
interact with those of the carbene-carbon atom, giving the
mesomeric limiting structures ( l a ) to ( I d ) . We have obtained
the first metalated carbenes, namely, triphenylstannyl- and
trimethylsilyl-ethoxycarbonylcarbene (5), by photolysing
ethyl diazo-(triphenylstanny1)- [v(Nz) = 2080 cm-1, v(C0) =
1670 cm-11 and -(trimethylsilyl)-acetate [v(Nz) = 2090 cm-1,
v(c0) = 1685 cm-11 in isobutene (0.03 M or 0.3 M, respectively)
until the solutions were decolorized 111. This affords ethyl 2,2dimethyl-l-(triphenyIstannyl)cyclopropanecarboxylate ( 6 a )
(yield 35 %) and the corresponding trimethylsilyl ester ( 6 6 )
(yield 49 %) , respectively, [v(CO) = 1710 cm-1 for (da),
1715 cm-1 for (66); NMR, AB spectrum of the cyclopropyl
protons, z = 8.7 (CCb), JAB = 4.5 Hz for (da), T = 9.0
(C6D,-j), JAB= 4 H z for (db)]. The starting materials (40)
F i g . 1. Half-cell for potentiodynamic current density measurements.
A: continuously increasing, or decreasing, reference voltage; B: electrolytic Ha-production for the H2-reference electrode; C: Hrreference
electrode: D: capillary: E: measuring electrode; F : counter electrode:
G: anodic or cathodic current flow caused by change of reference
Angew. Chem. internat. Edit.
Vol. 6 (1967) 1 No. I0
Без категории
Размер файла
121 Кб
trimethylsilyl, triphenylstannyl, ethoxycarbonylcarbene, diaz, ethyl, acetate
Пожаловаться на содержимое документа