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Di-e-cyclopentadienyltitanium Bis(hydrogen sulfide).

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Reactions of the kind described above may perhaps be models
for protein synthesis in the living cell.
slowly eliminates H2S with the formation of polycrystalline
oligomers containing Ti-S-Ti bonds.
Received: September 3rd. 1965 [Z 57/883 I€]
German version: Angew. Chem. 77, 965 (1965)
.
-~
L
L
J"
(2a), n = 1
(2b), n = 2
(la). n = 1
(lb), n = 2
[I] G . Wi[kinson and J. M . Birmingham, J. Amer. chem. SOC.76,
4281 (1954).
[2] By vapor-pressure osmometry (Mechrolab 301 A).
[3] Saturated solution, tetramethylsilane as external standard
(Varian A 60).
[4] S. A . Giddings, U.S.-Patent 3030395 (April 17th, 1962);
Chem. Abstr. 57, 9881 (1962).
Intermediate Occurrence of
1,2-Dehydrocyclooctatetraene
By Dr. A. Krebs
Institut fur Organische Chemie
der Universitat Heidel berg (Germany)
7
( H3 C ) zC - C Hz - C H -C Hz - H - f:( C H3 ) 2
HOOA
I
HOOC
HOOC
The ring strain and reactivity of 1,2-dehydrocyclooctatetraene
( I ) should lie between those of 1,2-dehydrobenzene, a confirmed but non-isolable intermediate, and of cyclooctyne [ I ]
which can be isolated.
(4)
COOH
[Z 591886 IE]
Received: August 27th, 1965
German version: Angew. Chem. 77, 965 (1965)
[I] Synthesis: H . Kammerer, W . Rauseh, and H. Schweikert,
Makromolekulare Chem. 56, 123 (1962).
Di-x-cydopentadienyltitanium
Bis(hydrogen sulfide)
After treatment of bromocyclooctatetraene [2] with a n ethereal
suspension of potassium t-butoxide and subsequent hydrolysis
potassium bromide was found in the aqueous phase in
a yield of 95 %. Separation of the reaction mixture gave,
apart from a high-melting, brown powder insoluble in
ether and benzene, t-butoxycyclooctatetraene(2) by distillation, b. p. 37-38 "C/0.05 mm, yield 16 %, and naphtho-2,3cyclooctatetraene (3), m.p. 113-1 14'C, yield 9 %, by
chromatography of the distillation residue o n silica gel with
cc14.
By Dr. H. Kopf and Prof. Dr. Max Schmidt
lnstitut fur Anorganische Chemie
der Universitat Marburg (Germany)
Di-n-cyclopentadienyltitaniumbis(hydrogen sulfide) (2) was
prepared in almost quantitative yield by the reaction of di-rcyclopentadienyltitanium dichloride ( I ) [ l ] with hydrogen
sulfide and the stoichiometric amount of triethylamine in
anhydrous ether (1 h at 2OoC):
(CsH&TiC12
(1)
+ 2 H2S + 2 N(C?H&
+ (CSH&Ti(SH)2 + 2 (CzH&N.HCI
(2)
Compound (2), which is surprisingly stable towards oxidation by air and toward hydrolysis, is freed from the accompanying amine hydrochloride by extraction of the mixture with water and is recrystallized from chloroform. The
brown-black, malodorous crystals decompose at 150-160 "C.
I n chloroform solution (2) is monomeric [2]. The 1H-NMR
spectrum in CHCI3 [3] contains two sharp signals, at 6.34
(C5H5) and at 3.44 (SH) ppm, with a n intensity ratio of 5 : 1.
As expected, the proton signal at 3.44 pprn is missing in the
spectrum (in CDC13) of the compound (CsH5)2Ti(SD)2
prepared analogously from D2S.
The presence of two S H groups was confirmed by iodometric
determination of the hydrogen sulfide quantitatively liberated by hydrogen chloride according t o
and by methylation with dimethyl sulfate t o di-x-cyclopentydienyltitanium bis(methy1 sulfide) 141. Compound (2)
does not react with diazomethane. I n boiling benzene it
Angew. Chem. internat. Edit. / Vol. 4 (1965)
/ No.
I1
The structure (2) was proved by elemental analysis,theNMR
spectrum, acid hydrolysis to cycloocta-l,3,5-trien-7-one
(isolated as the 2,4-dinitrophenylhydrazone[3]), and hydrogenation t o t-butoxycyclooctane, which was synthesized
independently from cyclooctanol. T h e structure (3) was
proved by elementary analysis, spectra (particularly NMR),
oxidation (by 0 3 and CH3C03H) to 1,2,4,5-benzenetetracarboxylic acid, and independent synthesis of 2,3-cyclooctenonaphthalene, which is obtained o n hydrogenation of
13).
The probable intermediacy of 1,2-dehydrocyclooctatrienein
this reaction of bromocyclooctatetraene was shown by trapping reactions: if the HBr elimination is carried out e.g. in the
presence of tetraphenylcyclopentadienone o r phenyl azide,
the adducts (4),m.p. 241-242OC, yield 1 2 %, and (5), m.p.
67.5-68 O C , yield 38 %, respectively, are obtained. The con-
953
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