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In metal-ammonia solutions the dissolved metal (or the electrons formed by dissociation) can exist in a paramagnetic, a diamagnetic, or a metallic state. Emf measurements with the electrochemical cell PtlNa(s)lNa+ @-aluminalNa-NH3JPt, responding reversibly to Na+ ions and electrons, reveal the thermodynamics of the solutions. The standard chemical potential, molar entropy, enthalpy, heat capacity, and volume of the dissolved sodium in the paramagnetic state (solvated electrons in dilute solutions) are listed together with their changes connected with the transitions to the diamagnetic and to the metallic state at higher concentrations. All transitions are exothermic, accompanied by a decrease in entropy at -35 O C . The data suggest that the diamagnetic species is formed by spin compensation of two electrons including one Na+ ion to overcome Coulombic repulsion.

Electrons produced in a gaseous, liquid, or solid solvent are called dissolved electrons or excess electrons. These excess electrons can exist as quasi-free particles of high mobility in a delocalized state, comparable with electrons in a metal; or as bound particles of low mobility they can be localized within narrow limits-in a solvent cavity formed by repulsive forces. Localized electrons can also be solvated like normal ions. Characteristically, such solvated electrons exhibit broad and extensive absorption spectra in the visible to near infrared spectral range. The localized and delocalized states of the excess electrons can be in equilibrium with each other, such that a continuous transition of the properties between the limiting extremes can be observed. The reactions of the excess electrons with suitable acceptors (substrates) are initiated by an attachment-detachment equilibrium A +e-*Awhich is followed by further chemical rearrangements. The rate constants of these reactions vary by more than 15 powers of ten depending on the substrates and the solvents. Most of the properties of excess electrons in solution can be interpreted by means of a model which is easily understandable but quantitatively evaluated only with considerable effort.

Very little has been published about the base catalyzed hydrolysis of PET. This is especially important in view of the potential interactions between polyester fibers and various organic and inorganic bases used in dyeing, aftertreatment, and washing.Sodium or potassium hydroxide solutions normally attack only the surface of a PET fiber; however, changes in the fine structure of the inner part of the fiber after such treatment have been observed recently[371. The dielectric properties of the polymer and the formation of carboxylate ions on the fiber surface presumably present a barrier to the penetration of the polymer by hydroxyl ions. The formation of a skin around the fiber and the fact that the rate constant for base catalyzed hydrolysis of esters of dibasic acids is smaller than the rate constant for acid hydrolysis is taken as further evidence for the greater stability of polyester fibers in alkaline solutions than in acid solutions. The degradation of PET in the presence of amines is accompanied by the formation of amide bonds. The final formation of the terephthalic acid diamide takes place via oligoester amides and oligoamides [37,3* crystallinity was unattacked after 1 6 hours in aqueous methylamine, whereas samples having other morphological properties were considerably degraded. The attack by methylamine takes place in three stages: The initial attack is in the amorphous regions; in the second stage, scission produces more low molecular weight material and gives rise to an increase in the degree of crystallinity of the polymer; the third stage, distinguished by a gradual decrease in the rate of reaction, is attributed to a decrease in the rate of attack on both crystalline and amorphous regions.The rate of aminolysis in the presence of primary and secondary amines is of the same order of magnitude as the rate of alcoholysis [371. Tertiary amines react with polyester only at higher temperatures; but these reactions are not, as yet, fully understood. For example, the products of the thermal degradation of PET seem to react with the tertiary amine; the products of this reaction and the amine itself are subject t o further thermal and oxidative degradation. The known catalytic effect of hydroxyl compounds on the aminolysis of esters [411 further complicates the picture.The author gratefulry acknowledges permission by the Goodyear Tire and Rubber Company to publish this work. Received: June 8, 1967[A 622 IEI German version: Angew. Chem. SO, 225 (1968) [40] Chem. Engng. News 43, No. 20, p. 38 (1965 In the formulation of many chemical reactions, electrons are regarded as readily transferable particles, though their participation in these reactions cannot be directly observed. However, the discovery that electrons can be produced in various ways in suitable solutions and that they are stabilized by solvation and can thus be studied directly has recently led to a rapid growth of interest in these, the simplest and mcst reactive particles of chemistry. The solvated electron has physical properties that permi...

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