This work explores the use of hexagonal boron nitride (h-BN), a graphite-like compound, as a novel catalyst with base and acid functionalities. For use as a solid catalyst, the layered structure of h-BN was disrupted by ball-milling, exposing boron and nitrogen edge sites as well as increasing the surface area from 3 to ca. 400 m² g⁻¹. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and proton magic-angle spinning nuclear magnetic resonance spectroscopy (¹H MAS NMR) indicated simultaneous and adjacent formation of amino and hydroxyl groups by milling, which function as Brønsted base and acid sites, respectively. Analysis using color indicator reagents and pyrrole-adsorbed ¹H MAS NMR results revealed that the ball-milled h-BN had basic sites of strength +9.3 > H₋ ≥ +7.2, comparable to those of KY zeolite. Measurements of ³¹P MAS NMR of adsorbed trimethylphosphine oxide indicated that the ball-milled h-BN had weak acid sites, comparable to those in HY zeolite. Despite its weak basicity, the ball-milled h-BN showed high activity and selectivity toward β-nitroalkenes for the nitroaldol reaction (Henry reaction) and the Knoevenagel condensation, whereas nontreated h-BN did not show activity. The nitroaldol reaction was considered to proceed in two steps: the abstraction of a proton from nitromethane by the amino group and the formation of an imine followed by a nucleophilic attack of the deprotonated nitromethane. Kinetic isotope effect experiments using _D-substituted nitromethane revealed that the first step was the rate-determining step. Several nitroaldol reactions using a variety of monosubstituted benzaldehydes indicated that electron-donating groups enhanced the activity, suggesting that the formation of adjacent base and acid sites is responsible for it. This study shows the high catalytic activity of BN, a solid catalyst with moderate basicity and weak acidity.

这项工作探索了使用六方氮化硼（h-BN）（一种类石墨化合物）作为具有碱和酸官能团的新型催化剂的用途。为了用作固体催化剂，h-BN的层状结构通过球磨破坏，暴露出硼和氮的边缘位点，并将表面积从3增加到大约1。400 m ²  g ^-1。傅里叶变换红外光谱，X射线光电子能谱和质子魔术角旋转核磁共振光谱（¹ H MAS NMR）表明，通过研磨同时和相邻形成氨基和羟基，分别用作布朗斯台德碱位和酸性位。使用颜色指示剂和吡咯吸附剂进行分析¹H MAS NMR结果表明，球磨h-BN具有+9.3> H _-  ≥+7.2的碱性位点，与KY沸石相当。吸附的三甲基氧化膦的³¹ P MAS NMR测定表明，与HY沸石相比，球磨h-BN具有弱酸位。尽管其碱性弱，但球磨的h-BN仍具有较高的活性和对硝基硝基醇反应（亨利反应）和Knoevenagel缩合反应对β-硝基烯烃的选择性，而未处理的h-BN则未显示活性。认为硝基羟醛反应分两个步骤进行：通过氨基从硝基甲烷提取质子，形成亚胺，然后对去质子化的硝基甲烷进行亲核攻击。动力学同位素效应实验_D-取代的硝基甲烷表明第一步是速率确定步骤。使用多种单取代的苯甲醛进行的几次硝基羟醛反应表明，供电子基团增强了该活性，表明形成邻近的碱基和酸位是其原因。这项研究表明BN具有高的催化活性，这是一种具有中等碱性和弱酸性的固体催化剂。