April 5 , 1057
COMMUNICATIONS TO THE EDITOR
1765
e ca. 2.9 a t 250 mp, 4.2 a t 210 mp).' With pyrisec. (as compared to sec. for bulk water a t dine-sulfur trioxide in pyridine overnight a t room room temperature), temperature, V furnished the tetraacetylglucotroThese findings appear relevant to contact angle paeolate ion VI, isolated as the monohydrated hysteresis on smooth surfaces. The measurement potassium salt, m.p. 186.5-187' dec. (lit.8 187- of a contact angle involves displacement of a pe189" dec.), [ c z ] ~ * D-22.6' (water), identified by riphery formed by the three-phase junction across infrared spectrum with specimens deriveds from one of the phases. There is a natural length asnature. The ion was also isolated, in 53% yield sociated with this process, namely, the peripheral from V, as tetramethylammonium tetraacetyl- thickness 1. Just as the surface of discontinuity gl~cotropaeolate,~ m.p. 182.5-183.5' (anhydrous between two phases is not a mathematical surface, ~ D (water), converted in 94% so the periphery is not a mathematical curve, but form), [ c z ~ ~-18.9' yield by methanolic ammoniaslg to anhydrous will have a thickness of the same order of magnitetramethylammonium gl~cotropaeolate,~ the salt tude as the surface of discontinuity. This latter of I (R = C6H&!H2), m.p. 188-189.2' dec., [ c z ] ~ ~ Dthickness is normally taken as the distance over - 16.7' (water). The glucotropaeolate was iden- which concentration gradients are appreciable (at tical with a sample isolated from Tropaeolum equilibrium), and is of the order of magnitude of majzis seed by adsorption of an extracts on anion molecular dimensions. A parallel definition of exchange resin and elution with tetramethylam- peripheral thickness can be made, and it should be tnonium hydroxide. lo When the synthetic gluco- of the same order of magnitude. There is a nattropaeolate was treated with the usual protein ural time associated with this process, namely, fraction of yellow mustard, benzyl isothiocyanate the relaxation time 7 of the most slowly relaxing (11, K = C~H&HZ) was rapidly" formed in quanti- molecule a t the periphery. There is therefore a tative yield and was determined and isolated as natural displacement velocity V N = 1 / 7 . Let V benzylthiourea. be the actual displacement velocity; then if V We thank Drs. 0.-E. Schultz, A. Kjaer, and R.
