вход по аккаунту


An Optically Active Heteroocine.

код для вставкиСкачать
oxidation of formaldehyde exceeds by far that of acetaldehyde; a current density of up to 50 mA/cmz can be achieved
at voltages lower than 300mV. However, evolution of
gases at the electrodes is insignificant and it can be concluded
that the current-producing reaction step is the oxidation to
formic acid, which can be further oxidized only slowly. The
current density increases greatly with the concentration of
the aldehyde in the electrolyte.
Current density irnAicm'I
are not converted at W C electrodes under analogous experimental conditions.
At WC gas electrodes even carbon monoxide can be oxidized;
however, the current density (3 mA/cm* at 500 mV) is small
compared with that reached in the oxidation of hydrogen
(150 mA/cmz at 300 mV).
Received: July 21, 1969
12 56 IE]
German version: Angew. Chem. 81. 748 (1969)
[*I Dr. H.Binder, Ing. A. Kohling, Dr. W. Kuhn, and
Dr. G. Sandstede
Abteilung Grenzflachenforschung
Battelle-Institut e.V.
6 Frankfurt 90, Postfach 900160 (Germany)
[l J French Pat. 1436504 (1966), Licentia Patentverwertungs
GmbH; W. Kuhn, W.Lindner, G . Sandstede, French Pat. 1486723
(19671, Robert Bosch GmbH; F. A . Pohl, German Pat. Appl.
1496176 (1969), Licentia Patentverwertungs GmbH.
[2] H . Bohnt and F. A . Pohl, Wiss. Ber. AEG-Telefunken 41, 46
(1968); Lecture 3. Journees int. d'Etude des Piles a Combustible,
Brussels, June 1969.
131 H. Binder, A . Kohling, and G. Sandstede, Angew. Chem. 79,
903 (1967); Angew. Chem. internat. Edit. 6,884 (1967).
[4] H . Binder, A . Kohling, W . Kuhn, W . Lindner, and G. Sandstede, Advanced Energy Conversion, in press.
Fig. 1. Stationary galvanostatic current-voltage curves for the oxidation
of formaldehyde and acetaldehyde at tungsten carbide in 2 N H ~ S O Iat
70 OC.
The oxidation of acetaldehyde proceeds without evolution of
gas, i.e. only acetic acid is formed; carboxylic acids, however,
cannot be oxidized a t W C electrodes. Formic acid is a n exception, as it behaves as an hydroxyaldehyde; at sufficiently
high temperatures it oxidizes at voltages slightly above 0 mV
with evolution of C02. Gas is also evolved at the electrode at
90 "C under open circuit conditions, in this case it is probably
the evolution of carbon dioxide and hydrogen, which is due
to the dehydrogenation of the formic acid (HCOOH --f
C02 + H2). In the oxidation of formic acid the reaction rate
decreases substantially with decreasing temperature (Fig. 2).
An Optically Active Heteroocine
By G. Ege and W. Planer [*I
The IH-NMR spectrum of 7-methyl-4-phenyl-8H-l,3,5,6dithiadiazocin-2-one ( 5 0 ) shows an AB spectrum for the
methylene protons; a chiral conformation was deduced on
the basis of this fact[ir. Failure of the signals t o coalesce
when the sample is heated t o 150°C suggested that the
substance can be resolved into optical antipodes.
Optical resolution has now been achieved with the carboxyl
derivative (5b). Reaction of dimethyl terephthalate and
hydrazine hydrate (molar ratio 2:l) in boiling dioxane for
eight days afforded the methyl terephthalate hydrazide ( I )
in 60 % yield[21. In a series of reactions carried out in a
single flask (1. CS2 + KOH, 2. chloroacetone, 3. HCI), ( I )
gave the thiazolinethione (2) 180 %; m.p. 199-201 O C (from
methanol); 1H-NMR spectrum (CF3COOH): 6 = 2.44
(3H/d); 6 = 4.17 ( ~ H / s ) ;6 = 6.82 (lH/q); 6 = 8.12-8.45
(4H/m); J c H , - H ~= 1.2 Hz], which is cyclized t o the hydroCOOCH,
Current density irn Alcrn'l
Fig. 2 Stationary galvanostatic current-voltage curves for the oxidation
of formic acid at tungsten carbide in 2 N H2S04 at 50, 70, and 90 "C.
At 90 "C and 300 mV the current density is 5 mA/cm* and at
50 O C it decreases to about 10 % of this value. The anomalous
character of the curve at 9 0 ° C can easily be explained as
follows: A t open circuit the hydrogen formed as a result of
dehydrogenation of HCOOH determines the potential of the
electrode; the rest potential is about 0 mV. At low galvanostatic loading the hydrogen formed by dehydrogenation is first
oxidized. At higher current density the formic acid is oxidized
directly; this reaction requires a larger overvoltage. Above
300 mV the oxidation reaction is inhibited (clearly recognized
in periodic current-voltage curves), and the potential increases rapidly with only a slightly higher loading t o about
700 mV; presumably from this point onwards the tungsten
carbide itself is attacked.
N -NR - C S OC O O I I
H3C r
Several higher aldehydes (e.g. propanal, glycolaldehyde,
benzaldehyde) can also be oxidized, although in poor yield,
to the corresponding carboxylic acids; dark colored condensation products are usually formed a t the same time. Alcohols
7 58
Angew. Chem. internat. Edit.
1 Val. 8
No. 10
gen sulfate ( 3 ) on treatment with concentrated sulfuric
acid 11 31 185 %; m.p. 259-260 O C (decomposition); 1H-NMR
spectrum (CF3COOH): 6 = 2.97 (3His); 6 = 4.17 (3H/s);
8 = 7.90 (1 H/s); 8 = 8.17-8.51 (4H/m)].
If a solution of ( 3 ) in aqueous KOH, which has been allowed
t o stand at room temperature for several hours, is added
dropwise t o boiling dilute hydrochloric acid, compound
(56) is obtained [80 %; m.p. 230 O C (decomposition);
IH-NMR spectrum ([D6]-DMSO): 8 = 1.85 (3H/s); AB
system: 8~ = 3.76, 8~= 3.46, JAB = 10 Hz; 6 = 7.8S8.20
(4H/m)]. The yellow compound (4). which is precipitated on
acidification of a cooled alkaline solution of ( 3 ) ,is formed as
intermediate in the above reaction [90 %; m.p. 208-212OC;
U V spectrum (methanol): hmax = 411 (E = 330), 291 (8040),
and 251 nm (18800)l. Compound ( 4 ) can be converted into
( 5 b ) both thermally and by the action of acids.
The optical resolution of (56) was carried out with brucine
in methanol. After repeated recrystallization from methanol
= -885
the brucine salt shows a specific rotation of [or]$&
(c - 0.5; chloroform). Decomposition of this salt with dilute
hydrochloric acid gave levorotatory (5b) having a specific
= --2250° (c = 0.5; acetone). The O R D
rotation of
curve exhibits the expected Cotton effect. Dextrorotatory
f5b) was obtained by working up the mother liquor of the
brucine salt.
To the best of our knowledge, the heteroocine (5b) is the
first eight-membered, monocyclic heterocycle not fused t o a
benzene nucleus whose chirality does not arise from an
asymmetric C atom and whose optical resolution has been
achieved. Moreover, the activation parameters for ring
inversion are exceptionally high. We calculated the following
values from the rate of racemization of (5c) bearing in mind
that kraC = 2 kinv: EA = 30.6 kcal!mole, log A = 12.1, and at
120°C AG* = 32.1 kcal/mole, AH* = 29.8 kcal!mole, and
AS* -= -6 e. u.
Attempts t o determine the optical purity of levorotatory
(56) from the N M R spectra (60 MHz) of a number of
diastereomeric derivatives of (5b) according to the method
of Raban and Mislow[4J were unsuccessful. Experiments t o
determine the optical purity by the method of isotopic
dilution are in progress.
xa 7
Received: July I I . 1969;
[Z58 I€]
German version: Angew. Chem. 81, 749 (1969)
c1 C1 CH,CH3
(Zb), X = B r
Only the electron-rich double bond of ( 3 ) reacts with ozone
in pentane at room temperature 141. On degradation according
t o the method given by Story151 the ozonide ( 5 ) loses acetic
anhydride, the thermal reaction leading t o tetrachloro-oxylene (7) whereas the photochemical process (CC14, -25 "C,
laboratory immersion lamp S-81, 1.4 amp, 15-20 h) gives
tetrachloro-o-(Dewar-xylene) ( 6 ) in 82 % yield. (6) was freed
from accompanying f 7) by vacuum sublimation.
Compound ( 6 ) undergoes thermal isomerization t o (7) and
has a half-life of 20 min at 120 O C and 9 h a t 90 "C.
Compd. [al
M.P. ("C)
NMR [b]
IR ( c a d )
U V (Amax)
169- 172
165- I66
8.41 (s), 8.83 (s)
1676 [c]
1610 [dl
1608 [dl
7.55 ( s )
239 nm
8.42 (s), 8.68 (s)
8.22 ( s )
[ * ] Priv.-Doz. Dr. G . Ege and Dip1.-Chem. W. Planer
Organisch-Chemisches Jnstitut der Universitiit
69 Heidelberg, Tiergartenstrasse (Germany)
[l] G . Ege, Angew. Chem. 79, 618 (1967); Angew. Chem. intern a t . Edit. 6 , 629 (1967).
121 The hydrazide ( I ) had previously only been obtained in small
amounts o n reaction of dimethyl isophthalate with hydrazine
hydrate; cf. L. A . Carpino, J . Amer. chem. SOC.79, 96 (1957),
particularly p. 98.
131 Compare the preparation of thiazolo[2.3-b]thiazolium salts:
C. K . Bradsher, D . F. Lohr, and W. J . Jones, Tetrahedron Letters
1965, 1723.
[4] M . Raban and K . Mislow in N . L . Allinger and E . L . Eliel:
Topics in Stereochemistry. Vol. 2, Interscience, New York 1967,
p. 199.
1610 [dl
1680 [cl
240 n m
(E =-= 2700)
1600 [dl
[a] All substances gave satisfactory elemental analyses.
[b] In CCII. TMS as internal standard,
7 scale.
[c] I ,2-Dimethylcyclobutene stretching vibration.
[dl 1.2-Dichlorocyclobutene stretching vibration.
I ,2,3,4-Tetrachloro-5,6-dimethyl(Dewar-benzene)
To a vigorously stirred, refluxing solution of (Za) (9.6 g) and
(26) (21.2 g) in anhydrous ether (50 ml) are added (i) 0.67 %
lithium amalgam (528 g) and (ii), dropwise over a period of
3 h, a solution of (Z) (33.4 g) in anhydrous ether (200 ml).
After two further hours the reaction mixture is filtered and
the mercury residue washed four times with 100 ml portions
of hot chloroform. The solvents are removed from the
filtrate and extracts, and the residue obtained is dissolved in
cyclohexane (200 ml) and filtered through aluminum oxide
(400 g). Washing of the adsorbent with pentane (1.5 I),
By R. Criegee and R. Huberr*]
removal of the solvents, and washing with cold methanol
yields a colorless crystalline mixture of ( 3 ) (8-9 g) and ( 4 )
1,2,3,4-Tetrachloro-5.6-dimethyl(Dewar-benzene) (1,2,3,4(2-3 g). The products can be separated by preparative thintetrachloro-5,6-dimethylbicyclo[2.2.0lhexadiene)(6)has been
layer chromatography on silica gel.
prepared by the following novel route: Treatment of a
mixture of hexachlorocyclobutene ( I ) []I and 3,4-dichloroA 10-g portion of the mixture of ( 3 ) and ( 4 ) in pentane
and 3,4-dibromo-l,2,3,4-tetramethylcyclobutene( 2 ) 121 in
(200 ml) is treated with a n excess of ozone at room temperaboiling ether with lithium amalgam afforded the mixed diture, whereupon a colorless crystalline precipitate is formed.
mer 1,6,7,8-tetrach~oro-2.3,4,5-tetramethylbicyclo[]The precipitate and mother liquor are transferred t o a
octadiene ( 3 ) in 15-20 % yield, alongside octachlorotricolumn packed with silica gel (400 g) and eluted with pentane
(4)[31. The products were separated
(1 I); 2-3 g of (4) can be isolated from the pentane eluate.
by preparative thin-layer chromatography.
The ozonide ( 5 ) is eluted from the column with a n ether/
Angew. Chem. internat. Edit.
/ VoI. 8 f 1969) 1 No. 10
Без категории
Размер файла
229 Кб
optically, activ, heteroocine
Пожаловаться на содержимое документа