How Molecular Structure Affects the Dissociation Timescales of Nitrate Esters

Nitrate esters are known as sensitive explosives due to the instability of the O-N bond. Femtosecond time-resolved mass spectrometry (FTRMS), a pump/probe technique, can be used to investigate the dissociation timescales of structurally related nitrate esters such as amyl nitrate (AN), ethylene glycol dinitrate (EGDN), and nitroglycerin (NG). Adding a nitrate ester group promotes faster dissociation to alkane ions, as shown by AN dissociating to the C₂H₅⁺ fragment three times faster compared to n-hexane. In turn, the addition of multiple nitrate esters groups further accelerates fragmentation, as seen by NG and EGDN dissociating four times faster than AN to produce the CH₂ONO₂⁺ ion. When comparing NG and EGDN, the NO₂, CH₂O⁺, and CHO⁺ ions return to their original values faster in NG, indicating that all dissociation pathways are completed faster in NG than EGDN. These results show that the dissociation timescales can be modified by changing the number and placement of nitrate ester groups, which can provide design principles to accelerate development of nitrate ester molecules for specific energetics applications.