Table 1.

Summary of hydrogen rearrangement rules [9]

Rule ID	Ion mode	Equationa,b,c	Cleaved terminal elementd
P1	Positive	M → [M′ − H]+	C, P, S
P2	Positive	M → [M′ + H]+	N, O, P, S
P3	Positive	M+ → M′+	C, N, O, P, S
P4	Positive	M+ → [M′ − 2H]+	C, N, O, P, S
N1	Negative	M → [M′ − H]−	C, N, O, P, S
N2	Negative	M → [M′ − 3H]−	C, P
N3	Negative	M → [M′ − 2H]−	S
N4	Negative	M− → M′−	C, N, O, P, S
N5	Negative	M− → [M′ − 2H]−	C, N, O, P, S

^aM and M′ indicate the neutralized (hydrogen-supplemented) form

^bRules of P1, P2, N1, N2, and N3 consider the neutralized form as the precursor

^cRules of P3, P4, N4, and N5 consider the ionized form as the precursor

^dBold face indicates the most frequent pattern