Oxygen-Interrupted Carbon Backbones in Liquid Energy Systems: A Structural Admissibility Condition for Drop-In Compression-Ignition Fuels

Description This document establishes oxygen-interrupted carbon backbones as a structural admissibility condition for liquid energy carriers claiming drop-in performance in compression-ignition systems, including diesel, jet, and marine applications. The analysis is non-constructive and does not disclose molecular structures, synthesis routes, blending ratios, additives, processing methods, or engine calibration strategies. Instead, it defines invariant structural conditions under which a liquid fuel can simultaneously achieve cold-flow disorder, compression-ignition survivability, and infrastructure compatibility without reliance on stabilizing additives or procedural compensation. Claims of drop-in liquid energy performance across real operating envelopes necessarily traverse this structural boundary. This condition constrains patentability at the level of enablement, inventive step, and industrial applicability.