A breakthrough in Pyridine-N-OxkJes bv Reillv. New process technology. New lower price. Commercial availability. The N-oxide group activates the pyridine ring toward both electrophilic and nucleophilic aromatic substitution.
— the transformation of aliphatic halides to give aldehydes, +
RCH2CI -
0 II R-C-H
N02
n
Ο
HN03, Δ Ο
ci-
"Ί^ϊΤΟΙ
— the oxidation of a-halocarboxylic acids to give aldehydes and carbon dioxide,
90% yield 90% yield Alkyl groups in the 2- and 4-positions are activated toward condensation with aromatic al dehydes and undergo a variety of reactions not possible in the parent pyridine system.
R-C-COOH-
+ R-C-H + C02
cr
H
— the oxidative decarboxylation of carboxylic acids or their anhydrides, ο
R = H, CH 3 , 3-COOH, 4-COOH. More to come.
Ac2o +
yield
Pyridine-N-oxides are versatile chemical intermediates which also function as chemical reagents or catalysts. The N-oxides are gener ally prepared by oxidation of pyridine or its derivatives with a peracid. Because of the difficulty in separating acids from the weakly basic N-oxides, they have tra ditionally been expensive and dif ficult to obtain in high purity. The new process technology developed at Reilly has improved N-oxide pur ity, increased production capacity, and lowered the prices of most of our N-oxides by nearly 50%. The reactions outlined below illustrate the increased reactivity imparted to the pyridine ring by the N-oxide group and describe the utility of pyridine-N-oxide as a chemical reagent or catalyst.
CH3
RR' CH-COOH
•
r ^ ^ i ( )
" + R-C-R ' + C02
— the conversion of isocyanides to isocyanates.
CH20Ac % yield
+
03^-QU "
yield
When manipulation of the pyridine ring has been completed, the N-oxide group (if still present) can be removed under mild conditions with a variety of reagents. Pyridine-N-oxide functions as a chemical reagent when used in stoichiometric amounts as illus trated in the following examples:
Reilly Tar & Chemical Corporation
R-NEC-
Pyridine-N-oxide catalyzes the acylation of anilines when used in less than stoichiometric amounts.
COCI
NH2
*-©
6*6—-6
If you have forgotten how versatile pyridine-N-oxides are, write for our new brochure. Samples available on request.
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