ISSN 1070-4272. Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 3, pp. 499 500. Pleiades Publishing, Inc., 2006.
Original Russian Text I.M. Osadchenko, A.P. Tomilov, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 3, pp. 508 509.
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Electrocatalytic Synthesis of Isonipecotic Acid
I. M. Osadchenko and A. P. Tomilov
Volgograd Research and Technological Institute of Meat and Milk Cattle Breeding and Processing
of Cattle-Breading Products, Russian Academy of Agricultural Science, Volgograd, Russia
State Research Institute of Organic Chemistry and Technology, Moscow, Russia
Received December 21, 2005
Abstract An electrocatalytic synthesis of isonipecotic acid was carried out by cathodic reduction of isonico-
tinic acid in a membrane electrolyzer on a copper cathode activated with Raney nickel in an alkaline medium
under mild conditions.
DOI: 10.1134/S1070427206030360
Isonipecotic acid (INPA), 4-piperidinecarboxylic
acid, is an important intermediate product in synthesis
of biologically active compounds for medicine and
veterinary, in particular, it is used for preparing Ace-
clydine.
ide concentration 5 6 wt % in catholyte and 20
25 wt % in anolyte, temperature 20 30 C, and cata-
lyst content on the cathode surface 8 10 g cm . Tak-
ing into account that INPA is difficultly separated
from INA, in our experiments we ensured quantitative
cathodic reduction of INA by passing the electricity
in the amount exceeding the calculated value (6 F per
mol INA) by 65 70%. The maximal current efficiency
for INPA was 60%. We established that cathodic
reduction of INA proceeds by the following scheme:
2
It is known [1] that cathodic reduction of hetero-
cyclic compounds, among them pyridine, in an acid
medium allows preparation of dihydro derivatives and
dimeric products.
It was reported [2] that, in cathodic reduction of
isonicotinic acid anilide in alkaline media on a mer-
cury cathode at controllable potential, this substance is
quantitatively converted to its dihydro derivative.
COOH
COOH
C
CH
HC
HC
CH
In this study we developed a procedure for exhaus-
tive cathodic reduction of isonicotinic acid (INA).
H C
CH2
+ 6OH .
2
+
6H O + 6e
2
CH
H C
CH2
The cathodic reduction of isonicotinic acid was
studied in aqueous alkali on a cathode activated with
powdered Raney nickel. An electrolyzer of membrane
type was equipped with a nickel anode and a flat
horizontal copper cathode. The powdered catalyst was
fixed on the cathode surface with a permanent magnet.
2
N
NH
The target product was isolated in the form of
INPA hydrochloride which was used in further organ-
ic syntheses.
1
5 40 wt % aqueous alkalis were used as anolytes,
EXPERIMENTAL
and 3 10 wt % aqueous alkalis as catholytes. The
INA concentration was varied within 5 15%. The
catholyte and anolyte were stirred with a mechanical
stirrer (50 100 rpm). The catalyst amount on the
cathode surface was 5 15 g cm . In the course of
cathodic reduction, the temperature in the electrolyzer
was in the range 20 35 C.
Isonicotinic acid, sodium hydroxide, and hydro-
chloric acid were of the reagent grade.
2
Electrolyses were performed in a glass cylinder
with a lid holding a nickel anode incorporated into
a ceramic diaphragm. A hollow copper disk connected
to a voltage source was used as a cathode. The elec-
trolyzer was equipped also with a mechanical stirrer
and a connecting tube for removing gaseous elec-
trolysis products [3].
We found that the optimal conditions for cathodic
reduction of isonicotinic acid were as follows: initial
INA concentration 5 10 wt %, initial sodium hydrox-
499