Julie, 1960
529
YOTES
18.9 f 0.2 kcal. per mole found by the transpiration method over the same temperature range.3 The agreement between the spiral gauge data and t'he transpiration dat'a lends further support to the conclusion previously made that only monomeric BiC13exists in the vapor above liquid BiCl,. Bi-BiC1, Mixtures.-The vapor pressures of several Bi-BiC1, mixt'ures (obtained with the spiral gauge) are sho~viiin Fig. 1 for three temperatures, where they are compared with vapor pressures determined by the transpiration method. The rather large error limits are due to corrections that had to he made in these measurements for a permanent gas impurity which presumably was released by the Bi, or by reaction of impurities in the Bi with the BiCI,. It was fouiid that, this gas impurity could he a,iToided by maintaining the molten Bi-BiCla solution under vacuum for several minutes before sealing off the gauge. Comparison of the spiral gauge data with the transpiration results in Fig. 1 indicates Ohat they are in agreement within experimental error. In addition t o t,he results shown in Fig. 1 the pressures over a solution cont'aiiiiiig 0.95 mole fraction of Bi were nieastired aiid found t o he 103 f i mm. a t 356" and 232 i i mm. at 392". These are the same pressares that are found at' 0.41 mole fraction, and thus indicates that the measurements a t 0.41 and 0.94 were made in t,he two-phase region of the system, as would be predicted from phase diagram information. lo The values for the activities and the derived thermodynamic properties of BiCla can he found in a previous report,.? The activity of the BiC13 in these solutions, :IS is e\-ident' from the vapor pressure curves (Fig. I ) , o l q s Raoult's law a t low Bi concentration~hiit shows marked positive deviat,ioiis at higher (w11re~itratioiis. Acknowledgment.---'l'hc ;iutliors :ire iudehted to I h . C. AI. Iicllcy for helpful discussions (10) P. .J. J-~sillt,-1. .1. l ) ; ~ r n t . l l ,\V. G. Gcliliian a ~ u iV. \\. Ala5 C Y , I H I SJUCBS.LL,63, 2:iO ( l ! l . j ! l ~ .
r ,
Woods metal thermostat to temperatures giving the vapor pressures necessary for the desired flow rates through the capillary orifice in the neck of the flask. A Hoke packless vmuum value, maintained a t 200°, v a s used t o admit the flask to the hot zone for the duration of the pyrolysis experiment. The reaction zone was a 67.41 cc. quartz tube maintained at. pre-selected temperatures, rk0.5' bl- a suitably wound electric furnace. Pressures were measured by a novel type thermostat,ed null manometer described elseivhere.4 At the esit, the vapors passed through a trap a t 25" a.nd t\vo traps a t -80". The remaining volatilrs, after furt,her possible condensables were taken off at. - 196", were transfrrreti by aiisiliary m e r r u r - diffusion and Toepler pumps to ralibrated st,orage volumps for analyses by P V T measurements. Products.-Efforts wvere made to determne t'he hexaphenylethane collected in the first, recriver ( 2 5 ' ) by benzoyl peroxide t,itration.b Quantitat,ive results could not be ohtained owing to the large amount,s of triphenylmethane present in this mixture. The non-condensable gas at -196" was confirmed to be hydrogen both by its emission spectrum and by mass spectrometry. The latter established that. the gas was lOOyohydrogen within the limits of analyses; no traces of methane vere found in this gaseous fraction. The fraction collected a t -196" but not condensable a t -80" contained the CZ hydrocarbons evolved in the pyrolyses. This was found to be relatively small, a maximum of about 3% only being observed at' the highest temperature (743") and T V ~ Snot invest'igated further. The :thence of significant amounts of C? hydrocarbons indicated that complete decomposition of triphenylmethane was not occurring in t,he temperature range studied. The fraction rollected a t -80" and not condensable a t 25' a t these l o ~ v pressures was confirmed to be principally benzene (>go% j hv mass snwtrometrv. Ouantitative determinations established th& the ratio"of benzene /hydrogen in the pyrolyses was 7.5/1.0 a t 680".
Results
,1 summary of the data and kinetic results for the react,ioii velocity studies is given in Table I. The temperature range, 645-745", pressure range, 2-12 mm., and contact t'ime range, 0.15-2.1 sec. were invest'igated. The kinetic analysis was based on the rate of hydrogen evolution owing to the difficulty of quant'itative estimates of the small :Lniouiit s of hesapheiiylethaiie in the product mixtures. >I plot of the first-order rate tonstaiit's (Table 1) 1's. reciproctal temperatures ('I research. in has been measured by the decrease in the optical part, by grant+in-aid from Cnion Carhide Chenii- density at 350 mp (extinction coefficient, 1.50 X cali Co. and Mon-:into Chemical Co. i b gratefully 104 moles-' liter cm.-l). The initial yield of this ackiion Icdgcd The :iuthori: wish to th:tnk Sidney decolorization iii riioleculeb '100 P.V. is shown as A: W. Bell-oil, ailcv. dchon and Alichael Szivurc for function of the pH in Fig. 1. G(d(.colori~~tioti), -timul;ttiiig ( * o i i i i i i o i i t h i i i the coiirw of this work. however, is only eclual to G(- [ C ( S O , ) { ] - )if no colored reaction product is formed. In strongly lL1I)IOLYSIS OF ' ~ l i I N I T R O J I E T H . ~ SIl ~ S ~ alkaline solutions the decolorization occurs with u yield of 2.8 niolec~ules,/lOOe.v. which :ipproximntely .\Q17EOrTSSOLUTTOSS BY corresponds to G(0H). Jt increases ivith increasing ('0-fiO ;-R.UII.iTIOS hydrogen ion concentration up to thc value of 8.2 at pEI 0. This high radiation sensitivity of triiiiL
