Institute of Physical Chemistry , Polish Academy of Sciences , ul. Kasprzaka 44/52 , 01-224 Warsaw , Poland.
Department of Physical Chemistry, Faculty of Chemistry , Warsaw University of Technology , ul. Noakowskiego 3 , 00-664 Warsaw , Poland.
J Phys Chem B. 2019 Oct 3;123(39):8261-8267. doi: 10.1021/acs.jpcb.9b05211. Epub 2019 Sep 23.
Here, the study is focused on the synthesis and determination of physicochemical properties of four α-pinene secondary organic aerosol (SOA) products: -pinic acid, -pinonic acid, -norpinic acid, and -norpinonic acid. These encompass their thermal properties, solid-liquid phase equilibria, and dissociation constant (p). Thermal properties, including the melting temperature, enthalpy of fusion, temperature, and enthalpy of the phase transitions, were measured with the differential scanning calorimetry technique. These SOA components exhibit relatively high melting temperatures from 364.32 K for -pinic acid to 440.68 K for -norpinic acid. The enthalpies of fusion vary from 14.75 kJ·mol for -norpinic acid to 30.35 kJ·mol for -pinonic acid. The solubility in water was determined with the dynamic method (solid-liquid phase equilibria method), and then experimental results were interpreted and correlated using three different mathematical models: Wilson, non-random two-liquid model, and universal quasichemical equations. The results of the correlation indicate that the Wilson equation appears to work the best for all investigated compounds, giving rise to the lowest value of a standard deviation. -Norpinic acid and -pinic acid (dicarboxylic acids) show better solubility in the aqueous solution than -norpinonic acid and -pinonic acid (monocarboxylic acids), which affect the multiphase chemistry of α-pinene SOA processes. For -pinonic acid and -norpinonic acid, also pH-profile solubility was determined. The intrinsic solubility () for -norpinonic acid was measured to be 0.05 mmol·dm, while for -pinonic acid, it was found to be 0.043 mmol·dm. The acidity constants (p) at 298 and 310 K using the Bates-Schwarzenbach spectrophotometric method were determined. The p values at 298.15 K for -norpinonic acid and -pinonic acid were found to be 4.56 and 5.19, respectively, whereas at 310.15 K, p values were found to be -4.76 and 5.25, respectively.
在这里，研究集中在合成和确定四个α-蒎烯二次有机气溶胶（SOA）产物的物理化学性质：α-蒎酸、β-蒎酸、α-诺蒎酸和β-诺蒎酸。这些产物涵盖了它们的热性质、固液相平衡和离解常数（p）。使用差示扫描量热法测量了热性质，包括熔点、熔融焓、相变温度和相变焓。这些 SOA 成分表现出相对较高的熔点，从α-蒎酸的 364.32 K 到β-诺蒎酸的 440.68 K。熔融焓从β-诺蒎酸的 14.75 kJ·mol 到β-蒎酸的 30.35 kJ·mol 不等。采用动态法（固液相平衡法）测定了在水中的溶解度，然后使用三种不同的数学模型：威尔逊模型、非随机双液相模型和通用准化学方程对实验结果进行解释和关联。关联结果表明，威尔逊方程似乎对所有研究化合物都适用，得到的标准偏差值最低。β-诺蒎酸和α-蒎酸（二羧酸）在水溶液中的溶解度优于β-诺蒎酸和α-蒎酸（单羧酸），这影响了α-蒎烯 SOA 过程的多相化学反应。对于β-蒎酸和β-诺蒎酸，还测定了 pH 曲线溶解度。测定了β-诺蒎酸的固有溶解度（）为 0.05 mmol·dm，而对于β-蒎酸，发现其固有溶解度为 0.043 mmol·dm。使用 Bates-Schwarzenbach 分光光度法在 298 和 310 K 下测定了酸度常数（p）。在 298.15 K 时，β-诺蒎酸和β-蒎酸的 p 值分别为 4.56 和 5.19，而在 310.15 K 时，p 值分别为-4.76 和 5.25。
