solo
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Arylaziridines synthesis and comments.....
Synthesis of Arylaziridines
Stanley J. Brois
J. Org. Chem. 1962; 27(10); 3532-3534.
Abstract
Contrary to several reports in the chemical literature, the Wenker method has been successfully employed in the synthesis of 1- and 2-arylaziridines.
Thus, four typical 1-phenyl-2-amino-1-alkanolsa nd 2-anilinoethanol were readily esterified with sulfuric acid in quantitative yields. Cyclization of
the intermediary sulfate esters with alkali gave the desired phenylsubstituted
ethylenimines which were assayed for purity by gas chromatography and characterized by n.m.r. and infrared spectroscopy. The n.m.r. data for
2-phenylaziridine (styrenimine) and styrene oxide strongly suggest that geminal couplings in three-membered heterocycles depend not only on angular
factors but also on the heteroatom.
Note: I need some help understanding what they mean with the ....
"..was neutralized to a methyl red end point with 50 % aqueous sulfuric acid"
from the Experimental section here......
Experimental1*
Amino Alcohols.-Samples of I-phenyl-2-amino-1-ethanol
(Ia), 1-phenyl-2-amino-1-propanol (Ib), I-phenyl-2-amino- ,
1-butanol (IC), and 1-phenyl-2-amino-2-methyl-1-propanol
(Id) were provided by the Commercial Solvents Corp.,
Terre Haute, Indiana. The 2-anilinoethanol (IV) was
purchased from Distillation Products Industries, Rochester,
New York, and used without further purification.
2-Phenylaziridine (IIIa) .-An aqueous solution of onehalf
mole of Ia was neutralized to a methyl red end point
with 50% aqueous sulfuric acid, followed by addition of an
equal volume of acid solution. Water was removed by
heating the solution at 10-15 mm., finally at 130'. The
product crystallized and waa coarsely ground and heated at
120-130" under reduced pressure to constant weight.
Completion of the reaction was demonstrated by loss of the
calculated weight of water to give a quantitative yield of
product. An aqueous solution of the sulfate IIa was neutral
to methyl red.
...........additional references by Stanley J. Brois......on Aziridines.......solo
http://ifile.it/ogdz73m
[Edited on 12-5-2008 by solo]
Attachment: Synthesis of Arylaziridines.pdf (378kB)
This file has been downloaded 489 times
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not_important
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| Quote: | Originally posted by solo
...
Note: I need some help understanding what they mean with the ....
"..was neutralized to a methyl red end point with 50 % aqueous sulfuric acid"
from the Experimental section here......
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Methyl red's transition range is pH 4.8–6.0, changing from yellow to red. Depending on who you read, end point is an orange to red-orange colour, a
pH in the lower 5.x range.
So they add H2SO4 to neutralise the amine group, ph ~ 5.3, then dump in an equal additional amount of H2SO4.
That's at least how I read it.
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solo
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Thanks not_important ....I was sort of lost since my PH indicator shows red at PH1.....now I can proceed and see if this sulfur ester
will materialize....and since I'm working with a base that doesn't dissolve in water I had to chlorinate it so it can be in a water solution for the
conversion can take place......Oh yes I tried doing it to the base powder and all i got is fizzing and ashes....lesson learned!....next page......solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Nicodem
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| Quote: | Originally posted by solo
....and since I'm working with a base that doesn't dissolve in water I had to chlorinate it so it can be in a water solution for the conversion can
take place......Oh yes I tried doing it to the base powder and all i got is fizzing and ashes....lesson learned!....next page......solo
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If you chlorinated an aminoalcohol then there is no more alcohol to esterify. I assume you meant that you made a hydrochloride since that is the only
other thing that would make any sense. The aqueous solubility of the aminoalcohol in the experimental you gave has absolutely no role since while you
are adding the sulfuric acid it will go into the solution as the sulfate anyway. Hence the titration till acidic reaction so you figure out how much
H2SO4 is half molar equivalent and then add exactly the same volume to form the hydrogensulfate which upon dehydration forms the beta-amonioalkyl
sulfate. If you add too much H2SO4 you will get decomposition during the heating while stripping the water off under vacuum.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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solo
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| Quote: | Originally posted by Nicodem
I assume you meant that you made a hydrochloride since that is the only other thing that would make any sense. The aqueous solubility of the
aminoalcohol in the experimental you gave has absolutely no role since while you are adding the sulfuric acid it will go into the solution as the
sulfate anyway. Hence the titration till acidic reaction so you figure out how much H2SO4 is half molar equivalent and then add exactly the same
volume to form the hydrogensulfate which upon dehydration forms the beta-amonioalkyl sulfate. If you add too much H2SO4 you will get decomposition
during the heating while stripping the water off under vacuum. |
...............Yes I meant the HCl of the amino alcohol....since adding the conc H2SO4 made no sense as it made ashes of the amino alcohol.....thanks
for the clarification ......sometimes the obvious is never clear to me....must be the years ................solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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chemrox
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why call it Winkler? why lower P?
It it possible that the author misnamed this method? It seems to me the "Winkler method" involved making the acid salt and then dehydrating with
heat. In this procedure the esterification takes place first. In both the intermediate is a sulfate bridge but it seems the Winkler method is
predicated on a different first step. I also wondered if anyone knows why lower pressure would help bring this to completion? Winkler had trouble
with charring and maybe the explanation lies therein.
Attachment: Winkler procedure.pdf (116kB)
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