Roger S. Stringham

Catalyzed Dissociation of N2 in Microwave Discharges. I

Atomic nitrogen, produced from very pure nitrogen in a microwave discharge and detected by means of electron paramagnetic resonance, was increased from 2.0×1013 atoms/cm3 to 1.2×1015 atoms/cm3 by the addition of ≈5×1012 molecules/cm3 of SF6 to the gas before the discharge; the pink glow intensity also is increased several orders of magnitude and its time duration extended by ≈10. Nitric oxide and oxygen increase the number of atoms leaving the discharge to the same extent as SF6, but much larger amounts must be added. When nitric oxide is added between the discharge and the subsequent pink glow, comparable increases in atomic nitrogen concentration (≈20 times) are observed without the production of oxygen atoms.

Ultrasonic photolysis of methyl disulfide and hexafluorobutadiene

Abstract An ultrasonic photolytic method was described for preparing adducts of hexafluorobutadiene and methyl disulfide. In the presence of an excess CH 3 SSCH 3 , the major product was trans -1,4-bis(methylthio)hexafluoro-2-butene. The minor products were the 1:2 adducts (CH 3 SSCH 3 ·2C 4 F 6 ) in the presence of a mixture, which consisted of a small amount of other oligomeric mixtures and isomeric 1:1 adducts.

Electrophilic additions involving fluoronium ions II. The addition of fluoroxy groups to perfluoro-aromatic compounds

Abstract The addition of fluoroxy groups to perfluoroaromatic compounds results in the formation of stable adducts. Thus, for the reaction of equimolar quantities of hexafluorobenzene and trifluoromethyl hypofluorite, the main products are the 1,4-monofluoroxy and 1,2-monofluoroxy adducts, but the latter adduct is not detected in the corresponding reaction with perfluoro-t-butyl hypofluorite. Polyfluoroxy additions to perfluoroaromatic compounds occur more readily for (CF 3 ) 3 COF than for CF 3 OF in spite of steric hindrance in the former. The other OF-containing compound which has been studied is oxygen difluoride which reacts with hexafluorobenzene to form polymeric perfluoroalicyclic ethers. In contrast to nucleophilic reactions, fluoroxy addition reactions occur more readily with hexafluorobenzene than with octafluorotoluene, a result which may be attributed to deactivation of the fluoroaromatic ring towards electrophilic addition by the trifluoromethyl group.

Additional Observations of Chemiluminescence in Mixtures of Atomic Oxygen and Nitrogen

Reinvestigation of the nitrogen afterglow using specially purified nitrogen indicates that an intermediary or precursor in the reaction path leading from free nitrogen atoms to the emission state is quenched by N2 but not by He. The O2 atmospheric bands and the O I 5577‐A line were not detected at the NO null titration point. The O2 Herzberg bands are independent of pressure in both N2 and 1% N2 in He systems, indicating that equilibrium exists between the radiative state and free atomic oxygen.

Photochemical reactions of fluoroxyperfluoroalkanes with perfluorocycloolefins

Abstract Under photolysis perflouro-t-butyl hypofluorite readily undergoes one-electron reduction at -20°C in the presence of perflourocycloolefin, which functions as a fluoroxy fluorine atom acceptor, to yield bis(perflouro-t-butyl) peroxide as the major product. The other products are the simple adducts C 5 F 9 OC(CF 3 ) 3 and C 6 F 11 OC(CF 3 from the corresponding perfluorocycloofins C 5 F 8 and C 6 F 10 , the cleavage compounds of (CF 3 ) 3 COF (i.e., CF 3 COCF 3 and CF 4 ), the corresponding perfluorocycloalkanes, C 5 F 10 and C 3 F 12 , a small amount of vicinal perfluorodi-t-butoxycycloalkanes, and a trace of the dimers and oligomers. The formation of the peroxide (CF 3 3 COOC(CF 3 ) 3 confirms the homolysis of the O-F bond in (CF 3 ) 3 COF under photolysis. The photochemical reactions of CF 3 OF and perfluorocyloolefins at -60°C give mainly the simple adducts C 5 F 9 OCF 3 and C 6 F 10 OCF 3 from the corresponding perfluorocycloolefins. The other products are perfluoroalkanes, dimers, and oligomers, but the peroxide CF 3 OOCF 3 and pefluorodimethoxycycloalkanes are absent. This paper examines the differences between the products of reactions of primary and tertiary fluoroxyperfluoroalkanes with perfluorocycloolefins and discusses the mechanisms of these reactions.

Electrophilic additions involving fluoronium ions. I. Fluoroxy additions to perfluoro-olefinic bonds

Abstract The fluoroxy addition of perfluoro-t-butyl hypofluorite to hexafluoro-propene leads predominantly (> 95%) to perfluoro-n-propyl perfluoro-t-butyl ether. The unique structural orientation of this perfluoro-n-propyl product is of interest because the products of fluoride ion addition reactions have previously been reported as perfluoroisopropyl derivatives. The results obtained in this study provide a simple experimental demonstration of electrophilic attack by the O-F group, leading to the addition of the fluoronium ion to the more nucleophilic unsaturated carbon atom. The same mechanism as for a perfluoro-α-olefin applies in fluoroxy addition to a perfluorovinyl ether. The perfluoro-t-butoxy group also adds predominantly (> 95%) to the terminal unsaturated carbon atom.

Ultrasonic digestion of low molecular weight organics and bacterial decontamination in water

Abstract This study reports the use of ultrasound in destructing low molecular weight organic compounds (alcohols, ketones and aldehydes) in dilute concentrations and bacterial decontamination in water at ambient temperature. An aqueous flow cell system was assembled to measure the formate and acetate products by an on‐line ion chromatograph. The formation of formate and acetate supports an oxidative mechanism and increases with decreasing flow rates. The bactericidal effect of sonication in static water was found to increase with increasing sonolysis times and volumes of the headspace (argon atmosphere over atmospheric air) above the liquid in the enclosed vessel.

High pressure isomerization of 1,4-bis(methylthio)hexafluoro-2-butene to-1-butene

Abstract The complete bond migration of the internal olefinic bond of trans-1,4-bis(methythio)hexafluoro-2-butene(I) under high pressure to the terminal olefinic bond to form cis- and trans-1,4-bis(methylthio)hexafluoro-1-butene(II) is described. The Teflon-lined high pressure cell maintains a constant pressure at 16,000 atm and 180 to 200°C for 24 hours. The cis- and trans-II are elucidated from gas chromatography-mass spectroscopy, which shows two identical parent ions at m/e value of 255(C 6 H 6 F 6 S 2 + ), but at different elution times. The 19 FNMR data of the isomeric products are summarized. Elemental analysis of II is verified by double focussing high resolution mass spectrometer.

Temperature Effects on Electronic Spectral Absorptions of Aqueous Electrolyte Solutes I: An Optical Microautoclave

A high-temperature optical microautoclave for maintaining aqueous solution at elevated temperatures and pressures is described. The apparatus is being used to monitor the chemical processes taking place during temperature cyclings. Some spectra of copper(II) and iron(II) solutions are presented as examples up to 200°C and 15.3 atm estimated pressure.