chemical physics of discharges - Argonne National Laboratory

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tube serve? as the high voltare electrode. The action mixture was
circulated at a hi-h rate from top Lo bottom through the reactor by
means of a custom-made membrane pump constructed of Halon (registered
mark of Allied Chemical Corooration). $n inert gas, nitrogen or helium,
was introdwed at the top of the reactor and vented at the bottom
through a condenser. The temwerature of the reaction mixture was measured
at the exit of the discharpe. Temaerature control was ensured by
regulating the temperature of the circulating glycerol solution.
I
Current at the desired frequencies was produced by an audiofrequency
generator (Heathkit ?lode1 17-71?) cou2led with a 1000 VA
custom-madeamdifier. It was raised to high voltage by means of a 25
KV transformer. Lower voltages could be obtained by acting on the outgut
of the avlifier. The power input to the system was monitorcd by
nekns of a watt-meter (Westinphouse Type PYb, specially compensated
for high frequency work) at the primary circuit of the transformer.
Eastman W.iite Label chemicals were user! I ithout purification. In
a tjpicpl experiment 29.L~ grams nf maleic anhydride in 416 ml of cumene
were kirculated for two hours in the appmatus while the discharge was
mainth'ined at a power level of 400 watts. Nitrogen was suppli?d at the
rate o'f'50 al/min. The teqperatiire of the reclction mixture was 127O C.
Tne renction mixture iuas ccole.' to 20° C. and the resiilting crystals
were filtered and washed with 50 ml of cold benzene. Additional crystals
here obtained after the mother liquor had been condensed to one third
of its initbal volume by flash evaporation. T!ie combined product was
drier! at 50 '-C. in a vacuum oven. It weigned 5.18 grams and had melting
point 255-7' C. Elementary analysis and neutralization equivalent were
consistent with formula I1 (R = H, R' = i-Pr). The infra-red spectrum
showed absence of aromatic cnaracter. Flash evaporation of the unreacted
cumene and maleic anhydride left 23.0 grams of a viscous residue which
had neutralization equivalent corresponding to a mixture of a 1:l and
2:l adduct of maleic anhydride and cumene. It was assumed that it containLd
adduct of formula I (R = R' = Me) together with products of
further condensation with maleic anhydride. Infra-red and NMR spectra
were consistent with this assumption.
Similar results were obtainPd ~laing bencene, toluene, and ethylbenzene
as substrates. Chlorobenzene and nitrobenzene failed to yield
a crystalline product. "he exwrimental conditions and the results
are summarized in table I.
Dis cu s s ion.
It is apparent from the present results that maleic anhydride
forms an adduct of type IT with benzene and alkylbenzenes under the
influence of silent discharge. The generally accepted path of formation
of IT in photochemical (3) or gamma-radiation induced (10) reaction is
% I