Table 1. HPLC Relative Retention Times (RRT) of Selected Process Impurities and their Relative Percent Areas at Various Stages in the Development of the Direct Phosphorylation Reaction Using POCl₃.

entry	condition	pyrophosphate (10) RRT 0.58	psilocybin (6) RRT 1.0	RRT 1.9	psilocin (4) RRT 2.21	RRT 2.41
1	10 min post POCl3 addition	0.15	69.46a	9.27	1.9	2.08
2	1 h post POCl3 addition	0.10	74.12a	6.77	1.60	2.58
3	2.5 h post POCl3 addition	0.94	77.31a	0.99	0.45	2.23
4	24 h after quench	1.18	80.27	0.78	2.69	11.99
5	crude-isolated product	0.24	97.61	0.33	1.38	0.24
6	mother liquors from isolation	6.43	46.01	1.32	25.32	15.99
7	after MeOH reslurry	0.11	98.93	0.11	0.13	0.56
8	after 40 °C H2O reslurry (development scale)	0.04	99.86	ndb	0.10	nd
9	after 40 °C H2O reslurry dried product (kilo-scale)	0.11	99.55	nd	0.11	nd

^aIndirect indication of formation of 7 by microquench of the aliquot prior to HPLC analysis.

^bNot detected.