Electrochemical reduction of organic compounds

A process for the electrochemical reduction of an organic compound by bringing the organic compound into contact with a cathode, wherein the cathode comprises a support made of an electrically conductive material and an electrically conductive, cathodically polarized layer formed thereon in situ by alluviation.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a process for the electrochemical 
reduction of organic compounds. 
2. Description of the Background 
The electrochemical reduction of organic compounds has hitherto been used 
on an industrial scale only in exceptional cases, eg. for the cathodic 
dimerization of acrylonitrile. Because current densities were inadequate 
in economic terms, which meant that space-time yields (STY) were too 
small, current yields were too low, hydrogen was being formed, 
selectivities with a view to a number of possible reduction steps were too 
low, the special catalytically active cathodes were not sufficiently 
available on a technical scale and/or the on-stream times of the 
catalytically active cathodes were too short, it has hitherto not been 
possible for electrochemical reduction on cathodes to be utilized 
industrially. 
A computer-assisted simulation for electrochemical hydrogenation of glucose 
is described by V. Anantharaman et al. in J. Electrochem. Soc., 141, 
(1994) pp. 2742-2752, the results of this simulation being compared with 
experimental data by K. Park et al. which were published in J. 
Electrochem. Soc., 132, (1985) pp. 1850 et seq. and J. Appl. Electrochem., 
16, (1986) pp. 941 et seq.. As can be gathered from this publication this 
reaction, which is carried out using a continuous reactor comprising a 
sintered-glass disk and powdered Raney nickel embedded therein as the 
electrically conductive substance as the cathode, likewise generates 
hydrogen. 
It is also known, from publications on preparative organic electrochemistry 
(eg. Electrochimica Acta, 39, (1994) pp. 2109-2115) that anodes and 
cathodes used in preparative electrochemistry must have special 
electrochemical characteristics. Such electrodes are often fabricated by 
metallic or carbonaceous support electrodes being coated by means of 
suitably adapted coating methods such as plasma spraying, impregnation and 
stoving, hot pressing etc. (see, instead of many, EP-B 0 435 434). 
A drawback of these established fabrication methods is that the electrodes, 
after inactivation of the catalytically active layer, often have to be 
removed from the electrolytic apparatus and subjected to external 
regeneration, so that short catalyst on-stream times preclude economic 
utilization of the electrochemical synthesis system. A further drawback 
consists in the laborious preparation of the catalytically active layer as 
such and the difficulties in achieving adequate bonding to the support 
electrode. The development effort for a classic electrode coating process 
can in many cases be justified in economic terms only with major 
industrial processes such as chlorine-alkali electrolysis or the cathodic 
dimerization of acrylonitrile. The use of commercially heterogeneous 
catalysts is often not a practical option, because thermal transformation 
in the case of thermal coating processes or masking of the active regions 
in the case of cold-bonding processes cannot be precluded. 
A catalytically active electrode, which is constructed as a perfused filter 
layer comprising a suspension of finely disperse catalyst material on a 
porous base body, is used according to EP-B 0 479 052 in a process for 
separating metal ions from process waters and effluents. 
SUMMARY OF THE INVENTION 
In view of the prior art set forth hereinabove it is an object of the 
invention to provide a process for reducing organic compounds, which on 
the one hand gives high space-time yields, permits high selectivity in the 
case of multiply reducible compounds, which avoids the formation of 
hydrogen during the reduction and can be used on an industrial scale. 
This object is achieved according to the invention by means of a process 
for the electrochemical reduction of an organic compound by bringing the 
organic compound into contact with a cathode, wherein the cathode 
comprises a support made of a conductive material and an electrically 
conductive, cathodically polarized layer formed thereon in situ by 
alluviation. 
DETAILED DESCRIPTION OF THE INVENTION 
Within the scope of the novel process in the operational state this 
involves the catalytically active electrode being stabilized by the 
pressure drop at the electrically conductive, cathodically polarized layer 
formed by alluviation. For regeneration purposes, the catalytically active 
electrode can be resuspended by inversion of the flow and can be 
discharged, for example, by filtration or removal by suction. The 
reduction of organic compounds is therefore carried out on a system which 
is suitable for forming and dismantling a catalytically active electrode 
within the process, merely requiring interventions already established 
within the operational practice of a chemical plant, such as switching of 
pumps and final controlling elements. 
Used as the support for the electrically conductive, cathodically polarized 
layer are electrically conductive materials, examples to be mentioned 
being materials such as alloy steel, steel, nickel, nickel alloys, 
tantalum, platinized tantalum, titanium, platinized titanium, graphite, 
electrode carbon and similar materials and mixtures thereof. 
The supports are preferably present as a permeably porous material, ie. the 
support has pores. These may be woven, in the form of commercially 
available filter fabrics, from metal wires or carbon fibers. Common 
examples include filter fabrics of plain weave, twill weave, warp twill 
weave, chain weave and satin weave type. It is also possible to employ 
perforated metal foils, metal felts, graphite felts, edge filters, screens 
or porous sintered bodies as large-area supports in the form of plates or 
candles. The pore size of the support is generally from 5 to 300 .mu.m, 
preferably from 50 to 200 .mu.m. The support should always be designed so 
as to provide the largest possible open area, so that the pressure drops 
to be overcome in carrying out the process according to the invention are 
only minor. Normally, the supports which are readily usable within the 
scope of the present process have an open area of preferably at least 
about 30%, more preferably at least about 20% and especially about 50%, 
the open area being at most about 70%. 
The electrically conductive material used for the electrically conductive, 
cathodically polarized layer may be any electrically conductive materials, 
as long as these can be formed into a layer by alluviation against the 
above-defined support. 
The cathodically polarized layer preferably contains a metal, a conductive 
metal oxide or a carbonaceous material such as, eg. carbon, especially 
activated carbon, carbon blacks or graphites or a mixture of two or more 
thereof. 
The metals employed preferably comprise all the classic hydrogenation 
metals, in particular the metals of the Ist, IInd and VIIIth subgroup of 
the Periodic Table of the Elements, especially Co, Ni, Fe, Ru, Rh, Re, Pd, 
Pt, Os, Ir, Ag, Cu, Zn, Pb and Cd, of which Ni, Co, Ag and Fe are 
preferably used as Raney Ni, Raney Co, Raney Ag and Raney Fe, any of which 
may be doped with impurity metals such as Mo, Cr, Au, Mn, Hg, Sn or other 
elements of the Periodic Table of the Elements, especially S, Se, Te, Ge, 
Ga, P, Pb, As, Bi and Sb. 
The metals used according to the invention are preferably present in finely 
disperse and/or activated form. 
It is also possible to employ conductive metal oxides such as eg. 
magnetite. 
Furthermore, the cathodically polarized layer may also be formed solely by 
alluviation of the above-defined carbonaceous material. 
In addition, the cathode can be built up in situ by the abovementioned 
metals and conductive oxides, each on carbonaceous materials, in 
particular activated carbon, being alluviated on the support. 
The present invention therefore also relates to a process of the type 
herein referred to, the cathodically polarized layer containing a metal or 
a conductive metal oxide or a mixture of two or more thereof, applied to 
activated carbon in each case. 
Particularly worth mentioning among these are layers containing Pd/C, Pt/C, 
Ag/C, Ru/C, Re/C, Rh/C, Ir/C, Os/C and Cu/C, these again optionally being 
doped with impurity metals or other elements of the Periodic Table of the 
Elements, preferably S, Se, Te, Ge, Ga, P, Pb, As, Bi and Sb. 
Furthermore, the abovementioned metals alluviated against the support may 
be in the form of nanoclusters, whose preparation is described eg. in 
DE-A-44 08 512 on surfaces such as eg. metals and carbonaceous materials. 
Additionally, the cathodically polarized layer may contain an electrically 
conductive adjuvant which improves adhesion of the abovementioned metals, 
metal oxides or nanoclusters on the support or enlarges the surface area 
of the cathode, electrically conductive oxides such as magnetite and 
carbon, in particular activated carbon, carbon blacks, carbon fiber and 
graphites being worth mentioning. 
In a further embodiment of the present process, a cathode is used which is 
obtained by the electrically conductive adjuvant first being alluviated 
onto the support and this adjuvant then being doped in situ, on the coated 
electrode, with these metals by means of reduction of salts of metals of 
the Ist, IInd and/or VIIIth subgroup. The preferentially used salts of the 
abovementioned metals are metal halides, metal phosphates, metal sulfates, 
metal chlorides, metal carbonates, metal nitrates and the metal salts of 
organic acids, preferably formates, acetates, propionates and benzoates, 
especially preferably acetates. 
In so doing, the cathode used according to the invention is built up in 
situ by the abovementioned metals or metal oxides being alluviated against 
the support either directly or after application of the electrically 
conductive adjuvant. 
The mean particle size of the particles forming the above-defined layer and 
the thickness of the layer are always chosen so as to ensure an optimum 
ratio of filter pressure drop and hydraulic throughput and enable optimum 
mass transfer. The mean particle size is generally from about 1 to about 
400 .mu.m, preferably from about 30 to about 150 .mu.m, and the thickness 
of the layer is generally from about 0.05 mm to about 20 mm, preferably 
from about 0.1 to about 5 mm. 
Note should be taken of the fact, in this context, that in the process 
according to the invention the pore size of the support generally exceeds 
the mean diameter of the particles forming the layer, so that two or more 
particles form bridges across the interstices while the layer is being 
formed on the support, this having the advantage that the formation of the 
layer on the support does not result in any significant obstruction of the 
flow for the solution containing the organic compound to be reduced. 
Preferably the pore size of the support is about twice to four times as 
large as the mean particle size of the particles forming the layer. Of 
course it is also possible, within the scope of the present invention, to 
employ supports having pore sizes which are smaller than the mean particle 
size of the particles forming the layer, although in that case a very 
close watch should be kept on the extent to which the flow is obstructed 
by the layer being formed. 
As already mentioned above, the cathode employed according to the invention 
is formed in situ by alluviation, against the electrically conductive 
support, of the constituents forming the layer, the solution which 
contains the particles forming the layer perfusing the support until the 
entire proportion of solids of said solution has been alluviated or 
retained. 
After the reduction is complete or when the catalytically active layer is 
spent, it can be separated from the support, by a simple switch of the 
flow direction, and can be disposed of or regenerated, independently of 
the reduction. After the spent layer has been completely removed from the 
system, it is then possible once more to recoat the support with the 
particles forming the layer and, after said particles have been completely 
alluviated, to continue the reduction of the organic compound. 
The current densities within the process according to the invention are 
generally from about 100 to about 10,000 A/m.sup.2, preferably from about 
1000 to about 4000 A/m.sup.2. 
The throughput of the solution containing the organic compounds to be 
reduced is generally from about 1 to about 4000 m.sup.3 /(m.sup.2 
.times.h), preferably from about 50 to about 1000 m.sup.3 /(m.sup.2 
.times.h). For a system pressure of, in general, from about 
1.times.10.sup.4 Pa (absolute) to about 4.times.10.sup.6 Pa, preferably 
from about 4.times.10.sup.4 Pa to about 1.times.10.sup.6 Pa, the pressure 
drop in the layer at the throughputs employed according to the invention 
is from about 1.times.10.sup.4 Pa to about 2.times.10.sup.5 Pa, preferably 
from about 2.5.times.10.sup.4 Pa to about 7.5.times.10.sup.4 Pa. 
The process according to the invention is generally carried out at from 
about -10.degree. C. up to the boiling point of the solvent or solvent 
mixture, temperatures between about 20.degree. C. and about 50.degree. C., 
especially close to room temperature, being preferred, however. 
The process according to the invention can be carried out, depending on the 
compound to be reduced, in an acidic medium, ie. at a pH below 7, 
preferably at from -2 to 5, more preferably at from 0 to 3, in a neutral 
medium, ie. at a pH of about 7, and in a basic medium, ie. at a pH above 
7, preferably at from 9 to 14 and especially at from 12 to 14. 
Especially preferably, the reaction is carried out at normal pressure and 
room temperature. 
Within the scope of the process according to the invention the sort of cell 
type used, the shape and the arrangement of the electrodes do not have any 
decisive effect, so that it is in principle possible to use any of the 
cell types customary in electrochemistry. 
By way of example the two following apparatus versions may be mentioned: 
a) Undivided cells 
Undivided cells with a plane-parallel electrode arrangement or candle-type 
electrodes are preferably used in those cases where neither starting 
materials nor products are adversely affected by the anode process or 
react with one another. The electrodes are preferably arranged so as to be 
plane-parallel, because this embodiment combines a narrow interelectrode 
gap (from 1 mm to 10 mm, preferably 3 mm) with homogeneous current 
distribution. 
b) Divided cells 
Divided cells with a plane-parallel electrode arrangement or candle-type 
electrodes are preferably used in those cases where the catholyte must be 
separated from the anolyte, eg. to preclude chemical side reactions or to 
simplify the subsequent separation of materials. The separating medium 
used can be in the form of ion exchange membranes, microporous membranes, 
diaphragms, filter fabrics made of materials which do not conduct 
electrons, sintered-glass disks and porous ceramics. Preference is given 
to the use of ion exchange membranes, especially cationic exchange 
membranes, the use of those membranes being preferred, in turn, which are 
made of a copolymer from tetrafluoroethylene and a perfluorinated monomer 
containing sulfo groups. Preferably the electrodes are in a plane-parallel 
arrangement even in divided cells, since this embodiment combines narrow 
interelectrode gaps (two gaps from 0 mm to 10 mm each, preferably anodic 0 
mm, cathodic 3 mm) with a homogeneous current distribution. Preferably the 
separating medium lies directly on the anode. 
What both apparatus versions have in common is the design of the anode. 
Suitable electrode materials used, in general, are perforated materials 
such as nets, metal meshes, lamellae, shaped webs, grids and smooth metal 
sheets. In the case of the plane-parallel electrode arrangement this is 
done in the form of planar sheets, in the embodiment comprising 
candle-type electrodes in the form of a cylindrical arrangement. 
The choice of the anode material and of its coating depends on the anolyte 
solvent. In organic systems graphite electrodes are thus used 
preferentially, whereas in aqueous systems preference is given to the use 
of materials or coatings with a low oxygen overpotential. Examples of 
acidic anolytes to be mentioned in this context are titanium or tantalum 
supports with electrically conductive interlayers onto which electrically 
conductive mixed oxides of the IVth to VIth subgroup are applied, which 
are doped with metals or metal oxides of the platinum group. 
With basic anolytes, iron anodes or nickel anodes are used preferentially. 
The solvents which can be used in the process according to the invention in 
principle include all protic solvents, ie. solvents which contain or 
release protons and/or are able to form hydrogen bonds, such as eg. water, 
alcohols, amines, carboxylic acids etc., possibly mixed with aprotically 
polar solvents such as eg. tetrahydrofuran (THF). Because of the ability 
to maintain the conductivity, preference is given in this context to lower 
alcohols such as eg. methanol, ethanol, 1-propanol, isopropanol, 
1-butanol, sec-butanol or tert-butanol, ethers such as eg. diethyl ether, 
1,2-dimethoxyethane, furan, tetrahydrofuran and dimethylformamide. 
Preference is also given to the use of water, possibly mixed with one or 
more of the abovementioned alcohols, ether and dimethylformamide (DMF), a 
mixture of water with methanol, THF or DMF being particularly preferred. 
As an alternative to the abovementioned alcohols it is also possible to 
employ the corresponding acids or amines. 
The carboxylic acids used are preferably fatty acids, among which the 
following may be mentioned: formic acid, acetic acid, propionic acid, 
butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, 
pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic 
acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, 
stearic acid, nonadecanoic acid, isobutyric acid, isovaleric acid. 
If organic compounds are used which are not soluble in the abovementioned 
solvents, these may, however, alternatively be brought into solution 
without difficulty by means of surface-active substances, especially 
higher alcohols as a solvent or solvent additive, fatty alcohols in 
particular being worth mentioning. The term fatty alcohols in this context 
refers to the following alcohols: 
1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 1-undecanol, 
10-undecen-1-ol, 1-dodecanol, 1-tridecanol, 1-tetradecanol, 
1-pentadecanol, 1-hexadecanol, 1-heptadecanol, 1-octadecanol. 
At the same time, of course, the corresponding alcohols carrying the 
hydroxyl group on different carbon atoms can likewise be used according to 
the invention. 
If higher alcohols or higher carboxylic acids or higher amines are used it 
should be borne in mind that the conversion then has to be carried out at 
relatively high temperatures, so as to maintain the viscosity of the 
solutions obtained within a range acceptable for carrying out the 
conversion. 
The reduction according to the invention is generally carried out in the 
presence of a supporting electrolyte. This is added to adjust the 
conductivity of the electrolysis solution and/or to control the 
selectivity of the reaction. The electrolyte content as a rule is at a 
concentration from about 0.1 to about 10, preferably from about 1 to about 
5 wt %, in each case based on the reaction mixture. Possible supporting 
electrolytes include protic acids such as eg. organic acids, among which 
methanesulfonic acid, benzenesulfonic acid or toluenesulfonic acid may be 
mentioned, and mineral acids such as eg. sulfuric acid and phosphoric 
acid. Additionally, the supporting electrolytes used may also be neutral 
salts. Eligible cations in this context are metal cations of lithium, 
sodium, potassium, but also tetraalkylammonium cations such as eg. 
tetramethylammonium, tetraethylammonium, tetrabutylammonium and 
dibutyldimethylammonium. Anions to be mentioned are: fluoride, 
tetrafluoroborate, sulfonates such eg. methanesulfonate, benzenesulfonate, 
toluenesulfonate, sulfates such as eg. sulfate, methyl sulfate, ethyl 
sulfate, phosphates such as eg. methyl phosphate, ethyl phosphate, 
dimethyl phosphate, diphenyl phosphate, hexafluorophosphate, phosphonates 
such as eg. methyl methylphosphonate and methyl phenylphosphonate. 
Also suitable for use are basic compounds such as eg. hydroxides, 
carbonates, hydrogen carbonates and alcoholates of alkali metals or 
alkaline earth metals, preference among alcoholate anions being given to 
the use of methylate, ethylate, butylate and isopropylate. 
Eligible cations in these basic compounds again include the abovementioned 
cations. 
It follows directly from what has been said above that the process 
according to the invention can be carried out not only employing a 
homogeneous solution of the organic compound to be reduced in a suitable 
solvent, but also in a two-phase system consisting of one phase which 
contains at least one organic solvent as defined above and the organic 
compound to be reduced, and a second water-containing phase. 
The electrochemical reduction according to the invention can be carried out 
either continuously or discontinuously. In both reaction modes the cathode 
is first prepared in situ by a catalytically active layer being formed on 
the support by alluviation. To this end, perfusion of the support by a 
suspension of the finely disperse metal and/or the conductive metal oxide 
and/or the nanocluster and/or the carbonaceous material, ie. the material 
to be alluviated, is carried out until essentially the entire amount of 
the material contained in the suspension is held on the support. Whether 
this is the case can be observed visually, for example by means of the 
suspension, which is turbid at the beginning of alluviation, becoming 
clear. 
If additionally an interlayer is to be alluviated, the support is perfused 
by a suspension of the material forming the interlayer, until essentially 
the entire amount used is held on the support. This is followed by the 
above-described procedure for alluviating the material which forms the 
cathodically polarized layer. 
If an interlayer is used, there is the additional option of perfusing the 
support, provided with an interlayer, with a solution or a suspension of a 
metal salt of a metal with which the support layer is to be doped, and of 
reducing, by applying a suitable voltage to the cell, the metal cations 
present in this solution or suspension in situ at the cathode. 
After the preparation of the cathode is complete, the organic compound to 
be reduced is then supplied to the system and is reduced by a previously 
precisely defined quantity of electricity being introduced into the 
system. Accurate control of the supplied quantity of electricity makes it 
possible, within the scope of the process according to the invention, to 
isolate even partially reduced compounds. 
In the case of complete reduction of the organic compounds used as starting 
materials, the selectivities are at least 70%, generally above 80%, and 
above 95% for reductions which proceed especially smoothly. 
In the course of the product prepared being isolated there is the option of 
possibly spent catalyst being replaced by means of the flow direction 
being reversed in the electrolytic cell, as a result of which the 
alluviated layer loses contact with the support and the catalyst can be 
removed eg. by removal by suction or filtration of the suspension 
containing it. 
Afterwards the layer can be built up once more as described above, and new 
starting material can then be supplied and converted. 
Furthermore, the steps of conversion (reduction), renewal of the catalyst 
and renewed conversion (reduction) can also be carried out alternately, 
the cathode first being prepared in situ by alluviation, as described 
above, the organic compound to be reduced then being supplied and 
converted, the flow direction within the electrolytic cell being changed 
after the conversion is complete and the spent catalyst being removed, eg. 
by being filtered off, the cathode then again being built up with fresh 
material forming the cathodic polarized layer and this being followed by 
continuing reduction. 
Of course this alternation between conversion, removal of the spent layer 
and renewal of the cathode can be repeated any number of times, as a 
result of which the process according to the invention can be carried out 
not only discontinously, but also continuously, which leads, in 
particular, to extremely short down-times during regeneration or when the 
catalyst is being replaced. 
In a further preferred embodiment of the process according to the 
invention, the electrolysis unit comprising at least one cathode with a 
shared catholyte circuit is operated in a steady state as a homogeneously 
continuous reactor. This means that after the catalyst has been alluviated 
once, a defined concentration level of starting materials and products is 
maintained. To this end the reaction solution is continuously recirculated 
by pumping across the electrochemically active cathode and the circuit is 
continuously supplied with starting material, product being drawn off 
continuously from this circuit, so that the reactor contents remain 
constant over time. 
The advantage of this process control strategy in comparison with the 
reaction being operated discontinuously consists in simplified process 
control involving less complicated equipment. 
The conversion-related drawback that it is necessary to put up either with 
unfavorable concentration conditions (ie. low starting material 
concentrations and high product concentrations at the end point of the 
conversion) or more laborious separation during work-up, can be 
counteracted by means of the following apparatus configuration, which is 
particularly preferred: 
At least two electrolysis units are connected in series, the starting 
material being supplied to the first unit and the product being drawn from 
the last unit. This mode of operation ensures that the first electrolysis 
unit(s) is(are) operated at distinctly more favorable concentration 
profiles than the last unit(s). This means that, averaged over all the 
electrolysis units, higher space-time yields are achieved than by managing 
the reaction so as to operate the electrolysis units in parallel. 
This cascade arrangement of the electrolysis units is particularly 
advantageous in those cases where the demanded production capacity in any 
case requires the installation of a plurality of electrolysis units. 
Organic compounds suitable for use in the process according to the 
invention in principle comprise any organic compounds containing reducible 
groups as starting materials. The products which can be obtained in the 
process include, depending on the total electric charge introduced, both 
partially reduced compounds and completely reduced compounds. Starting 
from an alkyne, for example, it is thus possible to obtain both the 
corresponding alkene and the corresponding, completely hydrogenated or 
reduced alkane. 
Preferably, organic compounds are reduced which have at least one of the 
following reducible groups or bonds: C--C double bonds, C--C triple bonds, 
aromatic C--C linkages, carbonyl groups, thiocarbonyl groups, carboxyl 
groups, ester groups, C--N triple bonds, C--N double bonds, aromatic C--N 
linkages, nitro groups, nitroso groups, C-halogen single bonds, more 
preferably an organic compound being reduced which is selected from a 
group comprising: nitriles, dinitriles, nitro compounds, dinitro 
compounds, saturated and unsaturated ketones, aminocarboxylic acids. 
The process according to the invention makes it possible to reduce, 
specifically, the following classes of organic compounds in particular. 
Organic compounds containing the following structural unit: 
EQU C.dbd.C (I) 
The above definition includes all organic compounds which contain at least 
one C--C double bond, such as eg. unsaturated carboxylic acids, aromatic 
compounds substituted by one or more alkenyl groups, and compounds of the 
formula (A) 
##STR1## 
where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each, independently of one 
another, hydrogen, alkyl, aryl, aralkyl, alkylaryl, alkoxyalkyl, alkoxy or 
acyl. 
Organic compounds containing the structural unit (II): 
EQU C.tbd.C (II) 
The above definition comprises all organic compounds which contain at least 
one C--C triple bond, such as eg. the compounds of the formula (B) 
EQU R.sup.1 -.tbd.-R.sup.2 (B) 
where R.sup.1 and R.sup.2 are as defined above. 
Organic compounds containing the structural unit (III): 
##STR2## 
The above definition comprises all organic compounds which contain at least 
one aromatic ring of the above formula, such as eg. all aromatic 
monocyclic or polycyclic hydrocarbons and monocyclic substituted aromatic 
compounds of the formula (C) 
##STR3## 
where R.sup.1 is as defined above and 
X.sup.1 can be halogen, alkoxy, NR'R", SR' and P(R').sub.2, where R' and R" 
may be identical or different and are as defined above for R.sup.1 to 
R.sup.4. 
Organic compounds containing the structural unit (IV) 
##STR4## 
where Y is NR', P(R').sub.3, oxygen and/or sulfur and R' is as defined 
above, 
R.sup.5 can be as defined above for R.sup.1 to R.sup.4 and additionally can 
be halogen, and 
n is an integer from 1 to 6, m is an integer from 1 to 4 and o and p are an 
integer from 1 to 3, the maximum number of the ring atoms being 12. 
The above definition comprises all organic compounds containing at least 
one heterocyclic ring, such as eg. 5-, 6- or higher-membered unsaturated 
heterocyclic compounds which contain from 1 to 3 nitrogen atoms and/or an 
oxygen atom or sulfur atom, for example compounds of the formula (D) 
##STR5## 
where Y, X.sup.1 and R.sup.1 are as defined above. 
Organic compounds containing the structural unit (V) 
##STR6## 
where X can be NR'", oxygen and/or sulfur, where R'" can be alkyl, aryl, 
alkoxy, hydrogen or hydroxyl. 
The above definition comprises all organic compounds containing at least 
one carbon-heteroatom double bond, such as eg. aldehydes, ketones and the 
corresponding thio compounds and imines, which can be represented by the 
following formula (E) 
##STR7## 
where X, R.sup.1 and R.sup.2 are as defined above and in addition also 
aliphatic or aromatic, saturated or unsaturated carboxylic acid 
derivatives, which then have the structure R.sup.1 COOR.sup.2, where 
R.sup.1 and R.sup.2 are again as defined above. 
Organic compounds containing the structural unit (VI): 
EQU C.tbd.N (VI) 
The above definition comprises all organic compounds which contain at least 
one C--N triple bond, such as eg. dinitriles and mononitriles, the latter 
being representable by the following formula (F) 
EQU R.sup.1 --C.tbd.N (F) 
where R.sup.1 is as defined above. 
Organic compounds containing the structural unit (VII): 
EQU C--X.sup.2 --O.sub.x R.sup.2.sub.y (VII) 
The above definition comprises all organic compounds containing at least 
one bond of the above type, ie. any heterocarbonyl analogues of the above 
type, among which nitro and nitroso compounds may be mentioned in 
particular, said heterocarbonyl analogues being representable by the 
formula (G) 
EQU R.sup.1 -X.sup.2 --O.sub.x R.sup.2.sub.y (G) 
where 
R.sup.1 and R.sup.2 are as defined above, 
X.sup.2 is nitrogen, phosphorus or sulfur, 
X is an integer from 1 to 3 and y is 0 or 1. 
Organic compounds containing the structural unit (VIII) 
EQU C-Z (VIII) 
where Z is fluorine, chlorine, bromine, iodine and/or alkoxy. 
The above definition comprises all organic compounds which contain halogen 
atoms as defined above or an oxyalkyl group, such as eg. saturated 
hydrocarbons or aromatic hydrocarbons which are substituted by at least 
one of the abovementioned groups and can be represented, for example, by 
the following two formulae (H) and (I) 
##STR8## 
where 
R.sup.1 to R.sup.3 and Z are as defined above, and 
R.sup.6 is as defined above for R.sup.1 to R.sup.4 and additionally can be 
formate, trifluoroacetate, mesylate and tosylate. 
Specifically, the following compounds or classes of compound can be 
converted: 
Unsaturated acyclic hydrocarbons having at least one double and/or triple 
bond corresponding to the above structures (I) and (II) which can be 
converted to give the corresponding saturated compounds or, if the 
starting materials contain more than one C--C double bond and/or at least 
one C--C triple bond, alternately to give the corresponding compounds 
which have at least one fewer double bond than the starting materials or 
instead of a triple bond a double bond. 
1. To be mentioned in particular in this context are alkenes having from 2 
to 20, preferably from 2 to 10 and especially from 2 to 6 C atoms, such as 
eg. ethene, propene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 
3-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 
1-hexene, 2-hexene, 3-hexene, 1-heptene, 2-heptene, 3-heptene, 1-octene, 
2-octene, 3-octene, 4-octene, 1-nonene, 2-nonene, 3-nonene, 4-nonene, 
1-decene, 2-decene, 3-decene, 4-decene, 5-decene, 1-undecene, 5-undecene, 
1-dodecene, 6-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 
1-hexadecene, 1-heptadecene and tetrahydrogeranylacetone. 
Alkynes having from 2 to 20, preferably from 2 to 10 and especially from 2 
to 6 C atoms, such as for example acetylene, propyne, butyne, pentyne, 
3-methyl-1-butyne, hexyne, heptyne, octyne, nonyne, decyne, undecyne, 
dodecyne, tridecyne, tetradecyne, pentadecyne, hexadecyne, heptadecyne, 
methylbutynol, dehydrolinalool, hydrodehydrolinalool and 1,4-butynediol. 
Polyenes and polyynes having from 4 to 20, preferably from 4 to 10 C atoms, 
such as, for example, butadiene, butadiyne, 1,3-, 1,4-pentadiene, 
pentadiyne, 1,3-, 1,4-, 1,5-, 2,4-hexadiene, hexadiyne, 1,3,5-hexatriene, 
1,3-, 2,4-, 1,6-heptadiene and 1,3-, 1,7-, 2,4-, 3,5-octadiene. 
2. Unsaturated monocyclic hydrocarbons having at least one double and/or 
triple bond. 
To be mentioned among these, in particular, are cycloalkenes having from 5 
to 20, preferably from 5 to 10 C atoms, such as, for example, 
cyclopentene, cyclohexene, cycloheptene, cyclopentadiene, cyclohexadiene, 
cycloheptatriene, cyclooctatetraene and 4-vinylcyclohexene. 
Cycloalkynes having from 6 to 20 C atoms, such as eg. cycloheptyne and 
cyclooctadiyne; 
monocyclic aromatic compounds having from 6 to 12 C atoms, such as, for 
example, benzene, toluene, 1,2-, 1,3-, 1,4-xylene, 1,2,4-, 1,3,5-, 
1,2,3-trimethylbenzene, ethylbenzene, 1-ethyl-3-methylbenzene, cumene, 
styrene, stilbene and divinylbenzene. 
3. Unsaturated polycyclic hydrocarbons having from 8 to 20 C atoms, such 
as, for example, pentalene, indene, naphthalene, azulene, heptalene, 
biphenylene, as-indacene, s-indacene, acenaphthylene, fluorene, phenalene, 
phenanthrene, anthracene, fluoranthene, acephenanthrylene, aceanthrylene, 
triphenylene, pyrene, chrysene, naphthacene, pleiadene, picene, perylene 
and pentaphene; 
4. Unsaturated polycyclic hydrocarbons having from 8 to 20 C atoms which 
are linked to one another via single or double bonds, such as, for 
example, biphenyl, 1,2'-binaphthyl and o- and p-terphenyl. 
5. Unsaturated heterocyclic systems containing units in accordance with the 
above structure (IV) having from 5 to 12 members which contain from 1 to 3 
nitrogen atoms and/or oxygen or sulfur atoms and at least one C--C double 
bond in the ring, which can be converted to give the corresponding 
heterocyclic compounds which have at least one fewer C--C double bond than 
the starting material, and if required can be converted to give the 
corresponding saturated heterocyclic compounds, such as, for example, 
thiophene, benzob!thiophene, dibenzob,d!thiophene, thianthrene, pyranes 
such as eg. 2H-pyrane or 4H-pyrane, furan, 1,4- and 1,3-dihydrofuran, 
benzofuran and isobenzofuran, 4aH-isochromene, xanthene, 1H-xanthene, 
phenoxathiine, pyrrole, 2H-pyrrole, imidazole, 4H-imidazole, pyrazole, 
4H-pyrazole, pyridine, pyrazine, pyrimidine, pyridazine, indolizine, 
isoindole, 3aH-isoindole, indole, 3aH-indole, indazole, 5H-indazole, 
purine, 4H-quinolizine, quinoline, isoquinoline, phthalazine, 
1,8-naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, 
carbazole, 8aH-carbazole, .beta.-carboline, phenanthridine, acridine, 
perimidine, 1,7-phenanthroline, phenazine, phenarsazine, phenothiazine, 
phenoxazine, oxazole, isoxazole, phosphindole, thiazole, isothiazole, 
furazane, phosphinoline, chromane, isochromane, 2-, 3-pyrroline, 2-, 
4-imidazoline, 2-, 3-pyrazoline, indoline, isoindoline, phosphindoline, 
1,2,3-, 1,2,4-, 1,3,4-, 1,2,5-oxadiazole, 1,2,3-, 1,2,4-, 1,3,4-, 
1,2,5-thiadiazole and 1,2,3-, 1,2,4- and 1,3,5-triazine. 
6. Organic compounds having at least one double bond between a carbon atom 
and an atom other than carbon, which is selected from nitrogen, 
phosphorus, oxygen and sulfur, as defined above as structure (V), N and P 
again, as defined above, optionally being substituted themselves, which 
can be converted to give the corresponding hydrogenated compounds, to be 
mentioned among which are, in particular, carbonyl compounds having from 2 
to 20 C atoms, preferably from 2 to 10 C atoms and especially from 2 to 6 
C atoms, such as eg. aliphatic and aromatic aldehydes such as eg. 
acetaldehyde, propionaldehyde, n-butyraldehyde, valeraldehyde, 
caproaldehyde, heptaldehyde, phenylacetaldehyde, acrolein, crotonaldehyde, 
benzaldehyde, o-, m-, p-tolualdehyde, salicylaldehyde, cinnamaldehyde, o-, 
m-, p-anisaldehyde, nicotinaldehyde, furfural, glyceraldehyde, 
glycolaldehyde, citral, vanillin, piperonal, glyoxal, malonaldehyde, 
succinaldehyde, glutaraldehyde, adipaldehyde, phthalaldehyde, 
isophthalaldehyde and terephthalaldehyde; ketones such as eg. acetone, 
methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, 
methyl isobutyl ketone, cyclohexenone, acetophenone, propiophenone, 
benzophenone, benzalacetone, dibenzalacetone, benzalacetophenone, 
2,3-butanedione, 2,4-pentanedione, 2,5-hexanedione, deoxybenzoin, 
chalcone, benzil, 2,2'-furil, 2,2'-furoin, acetoin, benzoin, anthrone and 
phenanthrone; 
saturated and unsaturated aliphatic and aromatic mono- and dicarboxylic 
acids having from 1 to 20, preferably from 2 to 10, more preferably from 2 
to 6 carbon atoms, such as, for example, formic acid, acetic acid, 
propionic acid, butyric acid, caprylic acid, capric acid, lauric acid, 
myristic acid, palmitic acid, stearic acid, acrylic acid, propiolic acid, 
methacrylic acid, crotonic acid, isocrotonic acid and oleic acid, 
cyclohexanecarboxylic acid, benzoic acid, phenylacetic acid, o-, m-, 
p-toluic acid, o-, p-chlorobenzoic acid, o-, p-nitrobenzoic acid, 
salicylic acid, phthalic acid, naphthoic acid, cinnamic acid, nicotinic 
acid, 
and substituted acyclic and cyclic carboxylic acids such as eg. lactic 
acid, malic acid, mandelic acid, salicylic acid, anisic acid, vanillic 
acid, veratroic acid, 
oxocarboxylic acids such as eg. glyoxylic acid, pyruvic acid, acetoacetic 
acid, levulinic acid; 
.alpha.-aminocarboxylic acids, ie. all the .alpha.-aminocarboxylic acids 
such as eg. alanine, arginine, cysteine, proline, tryptophan, tyrosine and 
glutamine, 
but also other aminocarboxylic acids such as eg. hippuric acid, anthranilic 
acid, carbamic acid, carbazic acid, hydantoic acid, aminohexanoic acid, 
and 3- and 4-aminobenzoic acid; 
saturated and unsaturated dicarboxylic acids having from 2 to 20 carbon 
atoms, such as eg. oxalic acid, malonic acid, succinic acid, glutaric 
acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 
maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic 
acid and sorbic acid, 
and esters of the abovementioned carboxylic acids, among which the methyl, 
ethyl and ethylhexyl esters should be mentioned in particular. 
7. Organic compounds containing units in accordance with structure (VI), 
ie. mono- and dinitriles having from 2 to 20, preferably from 2 to 10, 
more preferably from 2 to 6 carbon atoms, which can be converted to give 
the corresponding imines, amines or aminonitriles and diamines 
respectively. To be mentioned among these in particular are the following 
nitriles: 
acetonitrile, propionitrile, butyronitrile, stearonitrile, acrylonitrile, 
methacrylonitrile, isocrotononitrile, 3-butenecarbonitrile, 
propynecarbonitrile, 3-butynecarbonitrile, 2,3-butadienecarbonitrile, 
glutarodinitrile, maleodinitrile, fumarodinitrile, adipodinitrile, 
2-hexene-1,6-dicarbonitrile, 3-hexene-1,6-dicarbonitrile, 
methanetricarbonitrile, phthalodinitrile, terephthalodinitrile, 
1,6-dicyanohexane and 1,8-dicyanooctane. 
8. Heterocarbonyl analogues containing at least one unit of the 
above-defined structure (VII), of which nitro and nitroso compounds should 
be mentioned in particular, which in each case can be converted to give 
the corresponding reduced compounds such as eg. amines. 
To be mentioned in particular among these are aliphatic or aromatic, 
saturated or unsaturated, acyclic or cyclic nitro and nitroso compounds 
having from 1 to 20, preferably from 2 to 10, especially from 2 to 6 
carbon atoms such as eg. nitrosomethane, nitrosobenzene, 4-nitrosophenol, 
4-nitroso-N,N-dimethylaniline and 1-nitrosonaphthalene, nitromethane, 
nitroethane, 1-nitropropane, 2-nitropropane, 1-nitrobutane, 2-nitrobutane, 
1-nitro-2-methylpropane, 2-nitro-2-methylpropane, nitrobenzene, m-, o- and 
p-dinitrobenzene, 2,4- and 2,6-dinitrotoluene, o-, m- and p-nitrotoluene, 
1- and 2-nitronaphthalene, 1,5- and 1,8-dinitronaphthalene, 
1,2-dimethyl-4-nitrobenzene, 1,3-dimethyl-2-nitrobenzene, 
2,4-dimethyl-1-nitrobenzene, 1,3-dimethyl-4-nitrobenzene, 
1,4-dimethyl-2,3-dinitrobenzene, 1,4-dimethyl-2,5-dinitrobenzene and 
2,5-dimethyl-1,3-dinitrobenzene, o-, m- and p-chloronitrobenzene, 
1,2-dichloro-4-nitrobenzene, 1,4-dichloro-2-nitrobenzene, 
2,4-dichloro-1-nitrobenzene and 1,2-dichloro-3-nitrobenzene, 
2-chloro-1,3-dinitrobenzene, 1-chloro-2,4-dinitrobenzene, 
2,4,5-trichloro-1-nitrobenzene, 1,2,4-trichloro-3,5-dinitrobenzene, 
pentachloronitrobenzene, 2-chloro-4-nitrotoluene, 4-chloro-2-nitrotoluene, 
2-chloro-6-nitrotoluene, 3-chloro-4-nitrotoluene, 4-chloro-3-nitrotoluene, 
nitrostyrene, 1-(2'-furyl)-2-nitroethanol and dinitropolyisobutene, o-, 
m-, p-nitroaniline, 2,4-, 2,6-dinitroaniline, 2-methyl-3-nitroaniline, 
2-methyl-4-nitroaniline, 2-methyl-5-nitroaniline, 2-methyl-6-nitroaniline, 
3-methyl-4-nitroaniline, 3-methyl-5-nitroaniline, 3-methyl-6-nitroaniline, 
4-methyl-2-nitroaniline, 4-methyl-3-nitroaniline, 3-chloro-2-nitroaniline, 
4-chloro-2-nitroaniline, 5-chloro-2-nitroaniline, 2-chloro-6-nitroaniline, 
2-chloro-3-nitroaniline, 4-chloro-3-nitroaniline, 3-chloro-5-nitroaniline, 
2-chloro-5-nitroaniline, 2-chloro-4-nitroaniline, 3-chloro-4-nitroaniline, 
o-, p- and m-nitrophenol, 5-nitro-o-cresol, 4-nitro-m-cresol, 
2-nitro-p-cresol, 3-nitro-p-cresol, 4,6-dinitro-o-cresol and 
2,6-dinitro-p-cresol. 
9. Halogen-containing aromatic or aliphatic hydrocarbons or compounds which 
are substituted by an alkoxy group (as defined above as structure VIII and 
formulae G and H), which can be reduced to the corresponding hydrocarbons. 
To be mentioned as starting materials are, in particular, compounds having 
from 2 to 20 C atoms and from 1 to 6, preferably from 1 to 3 halogen 
atoms, preferably chlorine, fluorine, bromine or iodine, more preferably 
chlorine, fluorine, bromine and especially chlorine and bromine, such as 
eg. bromobenzene and trichloroethylene, but of course also any compound 
mentioned under items 1. to 7. and substituted by one or more of the 
abovementioned halogen atoms or an alkoxy group. 
10. Additionally, natural and synthetic dyes as described for example in 
detail in "Ullmanns Enzyklopadie der technischen Chemie", 4th Edition 
(1976), Volume 11, pp. 99-144, to be mentioned among which in particular 
are carotenoids such as eg. astaxanthine, carotene, quinone dyes such as 
eg. dianthronyl, alkannin, carminic acid, 
1,8-dihydroxy-3-methylanthraquinone, alizarin dyes such as eg. 1,2-, 1,3- 
and 1,4-dihydroxyanthraquinone, 1,2,4-trihydroxyanthraquinone, 
1,3-dihydroxy-2-methylanthraquinone and 
1,2-dihydroxy-1-methoxyanthraquinone, indigoid dyes such as eg. synthetic 
or natural indigo, indigotin, anile and 6,6'-dibromo indigo, pyrone dyes 
such as eg. flavone, isoflavone and flavanone. 
Especially preferably, the process according to the invention is employed 
for the following conversions: 
1. Conversion of the dinitriles of saturated aliphatic dicarboxylic acids 
into the corresponding aminonitrile, such as eg. the selective conversion 
of adipodinitrile into the aminocapronitrile while largely avoiding the 
complete reduction to hexamethylenediamine. 
Particularly suitable for this type of conversions are the following 
materials forming the cathodically polarized layer: 
Raney Ni, Raney Co and Pd/C, the conversion being carried out in a neutral 
to basic medium (pH from 7 to 14). 
2. It is also possible for dinitriles of aromatic carboxylic acids to be 
converted into the corresponding aminonitriles, such as eg. 
phthalodinitrile into 2-aminobenzonitrile, the following materials forming 
the cathodically polarized layer being employed in particular in this 
case: 
Raney Ni, Raney Co, the conversion again being carried out in a neutral to 
basic medium. 
3. Conversion of aliphatic or aromatic carboxylic acid dinitriles into the 
corresponding diamines, such as eg. the conversion of adipodinitrile into 
hexamethylenediamine. 
This conversion is preferably carried out with those materials forming the 
cathodically polarized layer as defined under 1. (dinitriles of aliphatic 
carboxylic acids) or those materials forming the cathodically polarized 
layer as defined under 2. (dinitriles of aromatic carboxylic acids), the 
conversion being carried out in each case under the conditions specified 
in 1. and 2., respectively. 
4. Conversion of imino-isophorononitrile into isophoronediamine 
The same materials forming the cathodically polarized layer and the same 
conditions are employed here as defined under 1. 
5. Conversion of aromatic dinitro compounds into the corresponding diamino 
compounds, such as eg. the conversion of dinitrotoluene to diaminotoluene 
For this purpose preference is given to the use of the following materials 
forming the cathodically polarized layer: 
Raney Ni and Pd/C, the conversion being carried out in an approximately 
neutral medium (pH from 5 to 7). 
6. Conversion of aromatic aminocarboxylic acids into the corresponding 
aminohydroxy derivatives, such as eg. the conversion of 2-aminobenzoic 
acid to 2-aminobenzyl alcohol, this type of conversion employing, in 
particular, the following materials forming the cathodically polarized 
layer: 
Cu catalysts such as eg. Cu/C, the conversion being carried out in an 
acidic medium (pH from 0 to 7). 
7. Conversion of natural and synthetic dyes into compounds which are 
hydrogenated on one or more C--C double bonds, such as eg. the conversion 
of indigo into leucoindigo and 1,4-dihydroxyanthraquinone into 
1,4-dihydroxy-2,3-dihydroanthraquinone, the following materials forming 
the cathodically polarized layer being employed in particular: 
Pd/C, Pt/C, Rh/C and Ru/C, the conversion being carried out in an acidic 
medium.

EXAMPLES 
Example 1 
Within a divided cell having an anode area and cathode area of 100 cm.sup.2 
each, a filter plate was installed which was covered with a 50 .mu.m warp 
twill fabric of alloy steel material No. 1.4571 as the cathode. Via a 
separate filtrate line the filtrate can be discharged from a cavity 
underneath the filter fabric. 
The anode employed was a titanium anode, designed to liberate oxygen and 
coated with Ta/Ir mixed oxide. The separating medium used was a NAFION-324 
cation exchange membrane (commercially available from Du Pont). The 
divided cell was incorporated into a twin-circuit electrolytic apparatus 
equipped with pump circuits. 
The conversion was carried out discontinuously in the following sequence: 
1100 g of 5% strength aqueous sulfuric acid were used as the anolyte. 
The catholyte was prepared by 5 g of vinclozoline 
(RS)-3-(3,5-dichlorophenyl)-5-methyl-5-vinyl-oxazoline-2,4-dione! being 
dissolved in a mixture of 500 g of water, 375 g of methanol, 375 g of 
isobutanol and 65 g of acetic acid. The cathode circuit was charged with 
1200 g of the catholyte batch. 
According to a titrimetric assay, the catholyte batch prior to the reaction 
is chloride-free. 
While the filtrate outlet was closed, 15 g of graphite powder were added 
into the circulating catholyte circuit and were dispersed in the 
circulation. Alluviation was effected by the catholyte circulation being 
shut and the filtrate outlet being opened. The pressure in the cathode 
compartment rose to 4.times.10.sup.5 Pa, and the filtrate throughput was 
12 l/h. This was followed by 5 g of catalyst (Degussa Type E101N/D, 10% Pd 
on carbon) being additionally alluviated in the same manner. Over a period 
of 30 min, a DC current of 20 A was then imposed which required a cell 
voltage of 35 V at the outset and as much as 7.5 V at the end of the 
experiment. 
According to a titrimetric assay, 850 ppm of chloride were detected in the 
output from the reaction, corresponding to a conversion ratio of 90%. 
Analysis of the obtained product by means of gas chromatography confirmed 
the following conversion: 
##STR9## 
Example 2 
The following example, which relates to the reduction of adipodinitrile 
(ADN) to hexamethylenediamine (HDA), and the subsequent examples were 
carried out in the following apparatus. 
Electrolytic cell: divided electrolytic cell of the flow-cell type 
Membrane: NAFION-324 
Anode: DeNora dimensionally stable anode (DSA) (anode area: 100 cm.sup.2) 
Cathode: Armor chain of alloy steel material No. 1.4571 (cathode area: 100 
cm.sup.2, pore size: 50 .mu.m) 
Throughput: about 20 l/h through the cathode. 
1200 g of 2% strength sulfuric acid were used as the anolyte. 
The catholyte consisted of a mixture of 693 g of methanol, 330 g of H.sub.2 
O, 22 g of NaOH, 55 g of adipodinitrile (0.509 mol) and 7.5 g of Raney 
nickel (BASF H.sub.1 -50). 
The conversion was carried out as follows: 
First the two cell compartments were charged, and then the Raney nickel was 
washed against the cathode over a period of 10 min. 
Then the electrolysis was carried out at between 30 and 40.degree. C. with 
a current density of 1000 A/m.sup.2 at normal pressure. The electrolysis 
was stopped after 8.5 F/mol of ADN. After the NaOH had been separated off 
by means of electrolysis the product was isolated by distillation. 56 g 
(95% based on the amount of ADN used) of hexamethylenediamine were 
obtained. 
Example 3 
The identical reaction apparatus, the identical anolyte and the identical 
catholyte as in Example 2 being employed, adipodinitrile was converted 
into 6-aminocapronitrile (ACN), the preparation of the cathode and the 
electrolysis being carried out in the same way as in Example 2, except 
that the electrolysis was terminated after only 4 F/mol of ADN. After the 
NaOH had been separated, followed by distillation, 38.7 g (0.34 mol, 68% 
of ADN) of aminocapronitrile, 16% of hexamethylenediamine and 14% of ADN 
were isolated. The selectivities were 79% for aminocapronitrile and 18.6% 
for hexamethylenediamine. 
Example 4 
The next conversion was carried out employing the identical apparatus and 
the identical anolyte as in Example 2. The catholyte employed was a 
mixture of 110 g (0.92 mol) of acetophenone, 638 g of methanol, 330 g of 
water, 22 g of NaOH and 7.5 g of Raney nickel. 
The preparation of the cathode and the conversion were carried out in the 
same way as in Example 2, except that the electrolysis was terminated 
after only 2.3 F/mol of acetophenone. 
After dilution with water (1 l) the product was isolated by extraction with 
5.times.200 ml of MTBE (t-butyl methyl ether), evaporation and 
distillation, and 101.3 g (yield: 90%, based on acetophenone) of 
1-phenylethanol were obtained. 
Example 5 
The reduction of 2-cyclohexanone to cyclohexanol was carried out employing 
the same apparatus and the same anolyte as in Example 2. The catholyte 
used was a mixture of 737 g of methanol, 330 g of water, 11 g of NaOH, 22 
g of 2-cyclohexanone and 7.5 g of Raney nickel. The conversion was carried 
out as in Example 2, except that the electrolysis was terminated after 6 
F/mol of 2-cyclohexanone. The output obtained was concentrated by 
distillation to 270 g, diluted with 500 ml of water and extracted with 
5.times.200 ml of MTBE. The organic phase was then distilled, and 21.7 g 
of cyclohexanol were obtained, which corresponds to a yield of 95% based 
on 2-cyclohexanone. 
Example 6 
This example was carried out in the same apparatus as in Example 2. 1100 g 
of 1% strength sulfuric acid were used as the anolyte. The catholyte 
consisted of a mixture of 418 g of methanol, 318 g of distilled water, 297 
g of sodium methyl sulfate solution, 7.4% strength in methanol, 55 g of 
cyclohexanone oxime (0.487 mol) and 8 g of copper powder. 
The conversion was carried out as follows: 
First the cell compartments were charged, and then the copper powder was 
washed against the above cathode over a period of 10 min. Then the 
electrolysis was carried out at a temperature of between 30 and 50.degree. 
C. with a current density of 1000 A/m.sup.2 at normal pressure. An 
electrical charge of 12 F/mol was applied, based on the oxime used. 
To work up the product, the catholyte was set to a pH of 13 with sodium 
hydroxide solution, the copper powder was filtered off, the filtrate was 
concentrated to 639 g and extracted 5 times with 100 g of MTBE each. After 
drying and removal of the solvent the crude product was distilled. 35.2 g 
of cyclohexylamine (73%, based on the oxime used) could be isolated as the 
reaction product. 
Example 7 
This example was carried out in the same apparatus as in Example 2. 1100 g 
of 1% strength sulfuric acid were used as the anolyte. The catholyte 
consisted of a mixture of 418 g of methanol, 330 g of distilled water, 297 
g of sodium methyl sulfate solution, 7.4% strength in methanol, 55 g of 
2-butyne-1,4-diol (0.64 mol) and 15 g of Raney nickel (BASF H1-50). 
The conversion was carried out in a manner similar to Example 6: 
An electrical charge of 4.5 F/mol was applied, based on the diol used. 
To work up the product, the catholyte was filtered, most of the filtrate 
was evaporated, and the crude product was distilled. 23 g of 
butanediol-1,4 and 12.4 g of 2-butene-1,4-diol could be isolated as the 
reaction product. 
Example 8 
This example was carried out in the same apparatus as in Example 2. 1100 g 
of 1% strength sulfuric acid were used as the anolyte. The catholyte 
consisted of a mixture of 704 g of methanol, 330 g of distilled water, 11 
g of sulfuric acid, 55 g of nitrobenzene (0.447 mol) and 8 g of copper 
powder. 
The conversion was carried out in a manner similar to Example 6: 
An electrical charge of 6.45 F/mol was applied, based on the substrate. 
To work up the product, the catholyte was set to a pH of 13 with sodium 
hydroxide solution, the copper powder was filtered off, the filtrate was 
concentrated to 597 g and extracted 5 times with 100 g of MTBE each. After 
drying and removal of the solvent the crude product was distilled. 26.2 g 
of aniline could be isolated as the reaction product. 
Example 9 
This example was carried out in the same apparatus as in Example 2, being 
modified in that an edge filter (pore size 100 .mu.m) made of alloy steel 
was employed as the cathode. 1100 g of 1% strength sulfuric acid were used 
as the anolyte. The catholyte consisted of a mixture of 806 g of methanol, 
377 g of distilled water, 52 g of sodium hydroxide solution, 48 g of 
2-thienylacetonitrile (0.391 mol) and 30 g of Raney nickel (BASF H1-50). 
The conversion was carried out at 21.degree. C. and a current density of 
1000 A/m.sup.2. The starting material was added in 14 batches. An 
electrical charge of 6.45 F/mol was applied, based on the substrate. 
To work up the product, the nickel powder was filtered off, the catholyte 
was neutralized with sulfuric acid and the methanol removed by 
distillation. After the pH had been set to 13, extraction with MTBE was 
carried out. After drying and removal of the solvent the crude product was 
distilled. 37 g of thienylethylamine could be isolated as the reaction 
product. 
Example 10 
This example was carried out in the same apparatus as in Example 2, being 
modified in that an edge filter (pore size 100 .mu.m) made of platinized 
titanium was employed as the cathode. 1200 g of 1% strength sulfuric acid 
were used as the anolyte. The catholyte consisted of a mixture of 651 g of 
ethylene glycol dimethyl ether, 651 g of distilled water, 28 g of sodium 
hydroxide solution, 70 g of 2-thienylacetonitrile (0.569 mol) and 50 g of 
Raney nickel (BASF H1-50). 
The conversion was carried out at 23.degree. C. and a current density of 
1000 A/m.sup.2. An electrical charge of 5.5 F/mol was applied, based on 
the substrate. 
To work up the product, the nickel powder was filtered off, and the 
filtrate was admixed with 4% of sodium hydroxide and saturated with NaCl. 
Separation of the phases was followed by distillation. 45 g of 
thienylethylamine could be isolated as the reaction product. 
Example 11 
This example was carried out in the same apparatus as in Example 2, being 
modified in that an edge filter (pore size 100 .mu.m) made of platinized 
titanium was employed as the cathode. 1200 g of 1% strength sulfuric acid 
were used as the anolyte. The catholyte consisted of a mixture of 882 g of 
methanol, 420 g of distilled water, 28 g of sodium hydroxide solution, 70 
g of veratryl cyanide (0.395 mol) and 50 g of Raney nickel (BASF H1-50). 
The conversion was carried out at 21.degree. C. and a current density of 
1000 A/m.sup.2. An electrical charge of 4 F/mol was applied, based on the 
substrate. 
To work up the product, the nickel powder was filtered off, the methanol 
removed from the filtrate by distillation and the remaining aqueous crude 
solution extracted 5 times with 100 g of MTBE each. After drying and 
removal of the solvent the crude product was distilled. 54.5 g of 
homoveratrylamine could be isolated as the reaction product.