3-Carboxy-1-methylpyridinium toluene-p-sulphonate 535-83-1 60388-20-7 EINECS 262-209-5 N-Methyl-3-carboxypyridinium p-toluene sulfonate Pyridinium, 3-carboxy-1-methyl-, salt with 4-methylbenzenesulfonic acid (1:1)