Chemistry is traditionally divided into organic and inorganic chemistry. HPLC of Formula: C5H7ClN4, The former is the study of compounds containing at least one carbon-hydrogen bonds.In a patent，Which mentioned a new discovery about 17645-17-9
Dimethyl and diethyl esters of cis-cyclohexane- 1,2- 1,3-, and 1,4-dicarboxylic acids cis-1, cis-2, and cis-3 give rise to major MH+ ions under ammonia chemical ionization (NH3-CI) conditions (minor [M + NH4]+) and to abundant [MH – ROH]+ ions under isobutane chemical ionization (i-Bu-CI) and collision induced dissociation (CID) conditions, indicating interaction between the two adjacent ester groups (stabilization of MH+ ion by hydrogen bridging and facilitating the ROH elimination by proton transfer between the two alkoxycarbonyl groups). Cyclohexane-trans-1,2-dicarboxylates trans-1 exhibit a similar interaction giving rise to major MH+ ions under NH3-CI and to abundant [MH – ROH]+ ions upon i-Bu-CI and CID. trans-1,4-Bis(alkoxycarbonyl)cyclohexanes trans-3, in which the two remote alkoxycarbonyl groups cannot interact, give rise to major [M + NH4]+ions under NH3-CI (minor MH+) and to negligible [MH – ROH]+ ions under i-Bu-CI and CID. trans-1,3-Diesters trans-2 behave in an unexpected way: They exhibit not only major [M + NH4]+ and minor MH+ ions under NH3-CI, in consistency with the large distance between the two ester groups, but also abundant [MH – ROH]+ ions under i-Bu-CI and upon CID conditions, indicating occurrence of a proton migration between the two alkoxycarbonyl groups. This behavior is explained in terms of a strained transition state or intermediate involved in the ROH elimination from MH+ of the trans-1,3-diesters. Methyl substituents at the two alpha-positions 1 and 3 increase the barrier for the proton transfer resulting in suppression of the ROH elimination from the MH+ ions of trans-1,3-dimethyl-1,3-bis(carboalkoxy)cyclohexanes trans-4 under i-Bu-CI and CID conditions.
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Reference：
Pyridazine – Wikipedia,
Pyridazine | C4H4N2090 – PubChem