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Monoethanolamine (MEA), the regenerative absorbent used in C02 scrubbers aboard nuclear submarines, is now stabilized with a chelating agent, the monosodium salt of , -diethanolglycine (VFS). This inhibitor is not effective against oxidative degradation at 55°C. in the presence of procatalytic metals, particularly copper. Effective stabilization in the presence of copper is given by tetrasodium (ethylenedinitrilo) tetraacetate (EDTA). At 98°C ., with small quantities of typical metal contaminants added, both VFS and EDTA are required for stabilization. The additive combination is ineffective at 138°and 149°C. with limited amounts of oxygen present. Pyrolytic stability of the formulation is adequate at these temperatures. VFS and EDTA are both true antioxidants for MEA in their own right. Their reactivity with peroxides, and their prevention of peroxide formation in oxidized MEA, suggest that their antioxidant activity results from an ability to interrupt an autocatalytic oxidation chain reaction. Less efficient additives did not prevent peroxide formation in MEA.

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N 1942 this laboratory undertook a basic investigation of the I problems involved in low temperature instrument lubrication.The results obtained using aliphatic diesters as lubricants have been reported (1-5, 6, 7,16, 25). It was found that a number of aliphatic branched-chain diesters possessed the requisite properties, for not only the lubrication of instruments but also many other military applications in aircraft and ordnance equipment. During the corresponding period, a German research group under the leadership of Zorn (58) investigated independently the use of esters as special-purpose lubricants and concluded that several branched-chain aliphatic esters were outstanding. Their work was later reviewed by Tingle (56) and by Horne (18).Since World War 11, a variety of special lubrication problems have arisen which increased interest in synthetic lubricants. Aircraft gas turbines, for example, require oils capable of providing adequate lubrication from temperatures of -65" to about 275" F. with temperatures on shutdown as high as 500" F. for intervals of 1 or 2 hours. Military automotive equipment is required t o operate a t what m-ere formerly considered prohibitively low temperatures (19). At high altitudes or in winter, machine guns and automatic cannon frequently could not be made to f i e because of congealed lubricants (56). Synthetic ester lubricants have received increasing application where petroleum lubricants cannot function satisfactorily. Therefore, this laboratory has endeavored, through its own research and through encouragement of industry, to extend the supplies of such lubricants by locating additional sources of native raw materials for their production and by developing new classes of esters (27). This report summarizes the progress since earlier publications (3, 6).Certain generalizations relating the structures of hydrocarbons to their viscometric properties were found valid for esters (6, 6, 8 25, 32, 32). These researches resulted in structural guides which reduced substantially the number of compounds required for synthesis and study. It was found that the high viscosity indexes of long-chain molecules are due to their ability to coil and uncoil reversibly with variations in temperatures ( I d , 31, 32).Such coiling is possible because of the freedom of rotation about the chemical bonds in the principal chain. Branching restricts the rotational freedom about these bonds and also increases the ratio of cross section to length of the molecule, both effects contributing to smaller viscosity indexes. Unbranched diesters have slightly lower viscosity indexes than the analogous hydrocarbons because the carbonyl oxygen behaves as a short branch chain.Unusual surface active properties-viz., ability to adsorb and orient at the solid-liquid interface, forming good wear-preventive f i l m e w e r e attributed to the diesters by Zorn (58). Brophy and Zisman (8) showed that the wear-preventive and rust-inhibiting properties of diesters were caused by the presence of impurities, as the pure compoun...