oxygen when a series of unsubstituted cyclic ethers are used as solvents. On the other hand, steiic hindrance dom inates the formation of solvated ion pairs when bulky substituents are lo cated close to the coordination site, as when a series of substituted tetrahydrofurans are used as solvents. The mechanism of carbanion reac tions ties closely to the type of ionic species present in a solution. The two kinds of ion pairs and the free ion may have vastly different reactivities, Dr. Smid says. The behavior pattern depends, too, on the type of reaction. For example the free ions in ethe real-type solvents generally have much higher reactivities than do contact ionpairs. Anionic polymerization of vinyl monomers in solvents such as T H F , tetrahydropyran, and dimethoxyethane exhibit this condition. The solvent-separated ion pairs also are very reactive, although probably not as reactive as free ions. A similar behavior is observed in proton abstraction reactions—for ex ample, in the reaction between sodium benzyl and triphenylmethane in T H F . However, a different pattern seems to emerge when fluorenyl carbanions are involved. Dr. Smid's re sults suggest that the cation catalyzes the proton transfer. The free ion then is not much more (and may be even less) reactive than the contact ion pair. The solvent-separated ion pair in this situation has a reactivity depending on how well the coordinat ing solvent molecules prevent the cat ion from catalyzing the proton trans fer, Dr. Smid says.
Water in lubricants shortens bearing life -ι rr 1ΟΟΤΗ
ACS NATIONAL MEETING Petroleum Chemistry
Small quantities of water dissolved in hydrocarbon lubricants cause up to 50% reduction in the fatigue life of rolling-element bearings. The mech anism by which water acts to shorten the life of ball and roller bearings in volves condensation into surface microcracks which act as capillaries, ac cording to a hypothesis developed by Paul Schatzberg and Ira M. Felsen of the Annapolis Division, Naval Ship Research and Development Center. This is but one of a number of hy potheses concerning causes of bearing failure now being investigated by en gineers and scientists. Little attention has been paid to systems where water is present as a minor constituent or impurity in the lubricant used on ball and roller 50 C&EN APRIL 8, 1968
embrittlement occur which, along with cyclic shear stress, accelerate crack growth to failure. The capillary crack condensation hypothesis predicts that barrier-film corrosion inhibitors would be ineffective since dissolved water would preferentially condense into the microcracks. This research shows that ability to dissolve water can be an important characteristic of lubricants, Mr. Schatzberg says. While not studied, other polar molecules such as am monia and hydrogen sulfide found in unusual environments will dissolve in lubricants and could shorten bearing life by concentrating in surface microcracks, he adds. RACE HOLDER. I. M. Felsen (left) and P. Schatzberg examine race holder used in their bearing lubricant studies
bearings and gears, Mr. Schatzberg told the Symposium on Chemistry of Lubrication. The symposium was jointly sponsored by the Divisions of Petroleum Chemistry and Colloid and Surface Chemistry. Water dissolves in hydrocarbons to the extent of several hundred parts per million at bearing operating tem peratures. The water comes from humid air and condensed moisture in the lubricant. Generally, solubility of water in saturated hydrocarbons decreases with increasing molecular weight but increases with tempera ture. Mr. Schatzberg and Mr. Felsen use an apparatus which allows a bearing ball to ride on top of three other bearing balls rolling in a race. This simulates the performance of an an gular-contact ball bearing. The appa ratus permits continuous flow of lubri cants. They used squalane as a standard lubricant. Bearing balls with diameters matched to within 5 millionths of an inch were selected to assure even loading. According to the idea proposed by the Navy scientists, fatigue life de creases because water condenses into surface microcracks in the steel balls, which causes the cracks to grow more rapidly leading to failure. Physical properties of water are important in its action. Water forms strong hydro gen bonds. This favors preferential adsorption and condensation of water into capillaries. Surface cracks are likely to be wedged-shaped with the tips or roots of the crack being very small. As lubricant is forced into cracks during rolling contact, the dissolved water condenses and forms a water-rich phase in the crack root. Then anodic and cathodic regions develop and corrosion and hydrogen
Compounds act against leprosy and tuberculosis 1ΓΓ 100TH
ACS NATIONAL MEETING Medicinal Chemistry
Two novel classes of antitubercular and antileprotic compounds have been synthesized at Parke, Davis & Co. Dr. Edward F. Elslager, group director in organic chemistry at the company's laboratories in Ann Arbor, Mich., finds that 1- {3- {[5,6,7,8-tetrahydro-4(phenylazo ) -1-naphthyl] amino} propyl} piperidines and 1- {3- {[ 5,6,7,8 - tetrahydro - 4 - ( 3-pyridylazo ) - 1 naphthyl] amino}propyl piperidines} Continued after Annual Report
/ = - Η , -CljOt-OCI^
POTENT QUARTET. The four com pounds above share potent antitubercu lar and antileprotic activity. Unfortu nately the only one tested (the chloro compound at top) is toxic to rats
