Estimation of Guanidine with Calcium Picrate

Abstract

Sharp end point. Reproducible results with cooling. Limited solubility Sharp end point. Linear plot. Soluble Insoluble Insoluble methacrylate rod stock, in order to determine the uniformity of monomer distribution throughout such a large cross section.Fractionation of the rod was accomplished by removing successive layers on a lathe. This operation was performed slowly to minimize heat effects and consequent polymer degradation.Table IV shows the data obtained from this experiment. Also included are data from several cast sheeting samples from which successive Vic-inch layers were obtained by milling.Oxidative Titration of Other Monomers. A number of compounds were subjected to oxidative titration as in the recommended procedure. Each of the compounds examined contained one or more terminal methylene groups as shown in Table V. Pertinent remarks concerning the behavior of these compounds on oxidative titration are also included.The compounds listed in Table V as giving sharp end points are those in which the terminal carbon-to-carbon double bond is conjugated with a strongly polar group such as carbalkoxyl, cyano, or aryl. These compounds are also soluble in the reaction medium.Solubility may prove to be a determining factor in extending oxidative titration to other compounds. Of the compounds exam-

Guanidine and Derivatives

“…Besides other methods such as spectroscopic and colorimetric methods, guanidine salts were formerly analyzed gravimetrically by precipitation as the picrate [18].…”

“…For convenient guanylation (amidination) of primary alkylamines and amino acids without formation of methanethiol, S-methylisothiourea sulfate 18, is a stable, unusually strong base, pK a 13.6 (25 • C), with a free imino group. It is a colorless to light-yellow liquid, miscible with water and common organic solvents: 0.92 g/cm 3 (25 • C), bp 160 • C, vapor pressure 0.03 kPa (25 • C).…”

Ion Exchange Separation of Ammonium and Guanidine Salts

“…Fainer ailcl Myers (2) clairn that their calciu~n picrate method for the determination of guanidine tolerates large amounts of am~noniuin salts as impurities. The results in Table 111 show that this is true u p to a ratio of 1 : 2 of a~nmonium to guanidine salt.…”