Irradiation of liquids

Irradiation of benzene and certain of its derivatives results in bond reorganization and formation of nonaromatic products. Irradiation of liquid benzene with light of 254-nm wavelength results in the accumulation of fulvene and a very small amount of tricy-clo[3.1.0.0 ]hex-3-ene, also known as benzvalene. The maximum conversion to this product in liquid benzene is about 0.05%. The key intermediate is believed to be a biradical formed by 1,3-bonding. 

This definition of electrochemistry disregards systems in which nonequilibrium charged species are produced by external action in insulators for example, by electric discharge in the gas phase (electrochemistry of gases) or upon irradiation of liquid and sohd dielectrics (radiation chemistry). At the same time, electrochemistry deals with certain problems often associated with other fields of science, such as the structure and properties of sohd electrolytes and the kinetics of ioific reactions in solutions. 

The photodimerization of simple isolated olefinic bonds is rarely observed because of the absorption of these compounds in the high-energy or vacuum-ultraviolet region. One case reported is that of the photo-dimerization of 2-butene.<2) Irradiation of liquid cw-2-butene with light from a cadmium (A = 229, 227, 214 nm) or zinc (A = 214 nm) lamp was reported to lead to dimers (1) and (2) ... 

Similarly, irradiation of liquid Pmy-2-butene yielded dimers (1) and (3) ... 

Relatively few examples of photoreactions of seven-membered and larger heterocycles have been reported. The major products of irradiation of liquid oxepin are hex-5-en-l-ol and hexanal234 photodecomposition of cyclic ethers has, in general been shown to be largely dependent on ring size. Irradiation of the valence bond isomer (287) of hexakis(trifluoromethyl) oxepin gave the unexpectedly stable oxet (288) via a mixture of (Z)- and... 

No spectroscopically detectable transient which absorbed above 240 nm was observed in the irradiation of liquid deoxygenated cyclohexane. 

Oxygen Difluoride Systems. The irradiation of liquid OF2 at 77° K. generally follows the lines established for NF3. The products are as shown below (unbalanced) ... 

The mass spectrum of isopropyl acetate contained a fairly strong signal at mfe 61, [equation (140], corresponding to the formation of acetic acid, on irradiation of liquid isopropyl acetate with helium ions... 

The first discovery of chemically induced dynamic electron polarization (CIDEP) was made by Fessenden and Schuler in 1963 (58). These authors observed the abnormal spectra of the H atoms produced during the irradiation of liquid methane. The low-field line in the esr spectrum was inverted compared to the corresponding high-field line. The related chemically induced dynamic nuclear polarization effect (CIDNP) was reported independently four years later by Bargon et al. (22) and by Ward and Lawler (134). Because of the wider application of nmr in chemistry, the CIDNP effect immediately attracted considerable theoretical and experimental attention, and an elegant theory based on a radical-pair model (RPM) was advanced to explain the effect. The remarkable development of the radical-pair theory has obviously brought cross-fertilization to the then-lesser-known CIDEP phenomenon. 

In 1963, Fessenden and Schuler [1] found during irradiation of liquid methane (CH4 and CD4) at 98 K with 2.8 MeV electron that the low-field signals (al and bl) for both hydrogen and deuterium atoms appeared inverted (emissive signals) and that the central deuterium atom signal (b2) was very weak as shown in Fig. 4-1. Although the cause of such anomalous ESR spectra was not clear at that time, similar anomalous ESR signals have been observed in many reactions and have been called Chemically Induced Dynamic Electron Polarization (CIDEP)". CIDEP should be due to non-equilibrium electron spin state population in radicals. 

Fig. 4-1. Second derivative ESR spectra observed for hydrogen atom (al and a2) and deuterium atom (bl, b2, and b3) with 2.8 MeV electron irradiation of liquid methane ( and deuteromethane) at 98 K. The observed spacings and the shifts from the first-order positions are indicated. The first-order positions of both hydrogen and deuterium atoms center at a field (indicated by the arrow) which corresponds to g = 2.00223. The tallest signal indicated by c is due to CDa- (Reproduced from Ref. [ 1] by permission from The American Institute of Physics)...

The most obvious immediate effect of high energy radiation upon an organic iodide would appear to be the formation of radicals resulting from the rupture of carbon-iodine bonds. Molecular iodine and largely hydrocarbon products would then result from interaction of the radicals with their own kind, with the parent molecules, and with other species present. Thus, Gillis etal. report the following products (G values in parentheses) from the °Co y-irradiation of liquid methyl iodide and ethyl iodide at room temperature. 

Schuler and Petry obtained the following compounds (G values in parentheses) after X-ray (120 kV) irradiation of liquid ethyl iodide and n-propyl iodide at room temperature. 

To provide further information on this point, we have investigated the y-radiolysis of benzene, toluene, ethylbenzene, and the xylenes in the vapor phase and have determined yields of the gaseous products, 4 polymer, and some products of intermediate volatility. These results are compared with those of parallel irradiations of liquid toluene and o-xylene and with published (2, 12) data for the other hydrocarbons in the liquid phase. 

Radiolysis of liquid T and X, at total doses of 108 to 109 rads, yields DT and DX, respectively. (DX is also a detectable product of the irradiation of liquid X at a partial pressure of 100 mm. of 02.) The isomers were positively identified by verification of their GLC retention times, infrared, and mass spectra. 

The spectral chracteristics of intermediates formed by irradiation of liquid ammonia probably do not differ greatly from those in metal-ammonium solutions (4) (Figure 3). In Figure 3, one sees the optical spectra of an intermediate which appears in the pulse radiolysis of liquid... 

During the irradiation of liquids, both ionization and excitation occur and its distribution is strongly affected by the LET value of radiation employed. In liquid alkanes, geminate ion recombination reaction takes place in the time range of one to ten ps [76], leading to the formation of the excited states. The excited states of alkanes have lifetimes of around Ins and decay to give mainly H2 and alkene products [77]. In ion beam radiolysis of liquid alkanes, at ns after... 

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