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Formyl Chloride.

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genes faecalis, which utilize (4) and ( 5 ) as sources of
nitrogen and carbon, deaminate these substances to the
respective lumazine derivatives, which then undergo
oxidation to 2,4,6,7-pteridinetetraone (163). The isomerization of (163) t o xanthine-8-carboxylic acid (164)
is achieved enzymatically.
6-methyl- or 6,7-dimethyl-5,6,7,8-tetrahydropterin
[319]
or by tetrahydrobiopterin indicates that a 6-substituted
tetrahydropterin is involved. The partially hydrogenated
pteridine derivative [320] produced in the course of the
hydroxylation is neither a 5,8- nor a 7,8- nor most
probably a 5,6-dihydropterin. Hence, it is likely that an
oxidation-reduction system is involved. This system may
have compounds (165) and (166) as components.
VII. The Biochemical Role of Unconjugated
Pteridines
By his study of the enzymatic hydroxylation of phenylalanine to form tyrosine, Kuufmun [317] has made a
valuable contribution t o the knowledge of the biochemistry of the pteridines [316]. H e was able to show
[317,318] that two enzymes are involved in the overall
reaction
H+
+ TPNH + 0 2
phenylalanine + TPN- i- HlO
- tyrosine
(where TI" = triphosphopyridine nucleotide and
T P N H = reduced TPN). One of the enzymes, isolated
from rat liver, catalyses the hydroxylation; it contains a
tetrahydrogenated, unconjugated pteridine as a cofactor. The second enzyme, obtained from sheep liver,
acts in conjunction with T P N H to induce rehydrogenation of the dihydropteridine to the tetrahydro stage.
Details of the structure of the cofactor are still unknown.
The fact that the cofactor can be replaced by either
[316] S. Kaufman [141.
[317] S. Knufman, J . biol. Chemistry 226, 5 1 I (1957).
[318] S. Kaufman, J . biol. Chemistry 230, 931 (1958).
This first example in which a simple unconjugated
pteridine plays the role of a cofactor can be considered
to be the beginning of a new chapter in the development
of pteridine chemistry. It does not seem improbable
that other biological functions of the pteridines will be
discovered in the near future.
Received, March IIth, 1963
[ A 335/134 IE]
German version: Angew. Chem. 75, 993 (1963)
[319] S. Kaufman, J. biol. Chemistry 234, 2577, 2683 (1953).
[320] S. Kanfman, J. biol. Chemistry 236, 801 (1961).
COMMUNICATIONS
Formyl Chloride
By Prof. Dr. H. A. Staab and Dipl.-Chem. A. P. Datta
Organisch-chemisches Institut der Universitat
Heidelberg (Germany)
When dry HCI is passed into a solution of an imidazolide (11
i n chloroform or methylene chloride, an acid chloride is obtained as a result of acqlation of the hydrogen chloride. Although the transacylation reaction (a) is reversible, as is shown
by the formation of imidazolides from acid chlorides and
imidazole, the acid chlorides are formed in practically quantitative yield, since imidazolium chloride formed in a subsequent reaction precipitates out. Acid chlorides whose synthesis hy the usual methods is attended by difficulties can be
prepared by this route, since imidazolides are readily accessible from carboxylic acids and I, 1'-carbonyldiimidazole.
of (1) obtained as filtrate was stable for one hour at -60 "C.
After addition of methanol, methyl formate was isolated
in 65-70 % yield. At -40 OC, we obtained only 9 "/, ester
under otherwise identical conditions. The thermal decomposition of ( I ) into CO and HCI, which is still being investigated quantitatively, was also followed by direct determination of the carbon monoxide evolved.
Received, August 16th. 1963: publication withheld until now at the
[ Z 563/445 IEI
request or the authors.
German version: Ansew. Chem. 75, 1203 (1963)
~
~~
[I] See H . A . Stanb, Angew. Chem. 74,407 (1962); Angew. Chem.
internat. Edit. I, 351 (1962).
[ 2 ] N. A . Staab and B. Polenski, Liebigs Ann. Chem. 655, 95
( I 962).
Dicyclopent adienyleuropium
By Prof. Dr. E. 0. Fischer and Dipl.-Chem. H. Fischer
lnstitut fur Anorganische Chemie der Universitat Miinchen
(Germany)
The long sought for formyl chloride (/) has now been
obtained on a preparative scale for the first time. We passed
HCI into a solution of I-formylimidazolr, [2] in CHC13
at -6O'C and filtered off the quantitative precipitate of
imidazolium chloride formed in the cold through a sintered
glass filter in a closed apparatus. The chloroform solution
132
Treatment of the blue solution of metallic europium in liquid
ammonia with cyclopentadiene in a ratio of 1 : 3.1, thermal
degradation of the yellow reaction residue at 200 OC in vacuo,
and rapid heating to 420-440 "C affords yellow dicyclopentadienyleuropium in 20 %, yield in the form of a crystalline
sublimate. This is the first "sandwich" compound prepared
Angew. Chem. internut. Edit.
1 Vol. 3 (1964) 1 No. 2
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