Figure 1.

IR spectra of dodecylguanidine free base (2). Most spectra were measured as saturated solutions in dry nonpolar solvents: benzene (A); CCl₄ (B); CH₂Cl₂ (C); CHCl₃ (D). An additional solution spectrum was measured in water-saturated CHCl₃ (E). A sixth spectrum (F), provided for comparison, represents crystalline (p-phenolyl)-dodecyl-guanidine free base (15) measured as a KBr pellet. Vertical scales were matched to facilitate comparisons. (More extensive ranges of these spectra from 1800 to 1100 cm^–1, and also including the corresponding ¹⁵N isotope-labeled compounds 2′ and 15′, are provided in Figures S-3–S-12 in Supporting Information.)