A polysulfide material was synthesized by the direct reaction of sulfur and d‐limonene, by‐products of the petroleum and citrus industries, respectively. The resulting material was processed into functional coatings or molded into solid devices for the removal of palladium and mercury salts from water and soil. The binding of mercury(II) to the sulfur‐limonene polysulfide resulted in a color change. These properties motivate application in next‐generation environmental remediation and mercury sensing.

Apolysulfide material was synthesized by the direct reaction of sulfur and d-limonene,b y-products of the petroleum and citrus industries,r espectively.T he resulting material was processed into functional coatings or molded into solid devices for the removal of palladium and mercury salts from water and soil. The binding of mercury(II) to the sulfurlimonene polysulfide resulted in acolor change.These properties motivate application in next-generation environmental remediation and mercury sensing.The exploration of sustainable feedstocks is important in the synthesis of functional materials.[1] Herein, we report the utility of apolysulfide synthesized directly from two industrial by-products:s ulfur [2] and d-limonene [3] (Scheme 1). This study was inspired by classic reports on the reaction of sulfur and limonene, [4] theu se of limonene as ar enewable monomer, [5] and the recent and innovative applications of "inverse vulcanization" to access av ariety of advanced materials with high sulfur content. [6] We found that the sulfur-limonene polysulfide can be processed into coatings and solid devices that remove metal salts such as palladium-(II) and mercury(II) from water and soil. We also report the discovery of ac hromogenic response when the polysulfide is exposed to mercury(II). As sulfur is produced annually in excess of 60 million tons as ab y-product of petroleum refining [2] and more than 70 thousand tons of limonene are isolated each year from orange zest in the citrus industry, [3] the sulfur-limonene polysulfide is inexpensive-further motivating its use in metal sequestration, sensing,and environmental remediation.As as tarting point, sulfur was melted (T > 120 8 8C) and then heated to 170 8 8C. Above 150 8 8C, SÀSb ond scission occurs, [7] thereby generating thiyl radicals that could add to limonene.A ne qual mass of limonene was added to the molten sulfur,w hich produced at wo-phase mixture that becomes as ingle,d ark red phase upon reaction. An equal mass of sulfur and limonene was chosen to maximize the content of both industrial by-products in the final material. 1 HNMR analysis of the reaction mixture indicated limonenes exocyclic alkene was consumed more rapidly than its endocyclic alkene,w ith complete consumption of all olefins within 90 min (see Figures S6-S8 in the Supporting Information). Little change was observed by 1 HNMR spectroscopy on further heating. Scheme 1. Synthesis and applicationso fasulfur-limonene polysulfide.

Suzuki–Miyaura cross‐coupling reactions between a variety of alkyl halides and unactivated aryl boronic esters using a rationally designed iron‐based catalyst supported by β‐diketiminate ligands are described. High catalyst activity resulted in a broad substrate scope that included tertiary alkyl halides and heteroaromatic boronic esters. Mechanistic experiments revealed that the iron‐based catalyst benefited from the propensity for β‐diketiminate ligands to support low‐coordinate and highly reducing iron amide intermediates, which are very efficient for effecting the transmetalation step required for the Suzuki–Miyaura cross‐coupling reaction.

An iron-catalyzed cross-coupling reaction between alkyl halides and arylboronic esters was developed that does not involve activation of the boronic ester with alkyllithium reagents nor requires magnesium additives. A combination of experimental and theoretical investigations revealed that lithium amide bases coupled with iron complexes containing deprotonated cyanobis(oxazoline) ligands were best to obtain high yields (up to 89%) in catalytic cross-coupling reactions. Mechanistic investigations implicate carbon-centered radical intermediates and highlight the critical importance of avoiding conditions that lead to iron aggregates. The new iron-catalyzed Suzuki-Miyaura reaction was applied toward the shortest reported synthesis of the pharmaceutical Cinacalcet.

Herein we report the development of diffusion ordered NMR spectroscopy (DOSY) for its use to characterize metal complexes containing paramagnetic first row transition metal elements.

A mechanistic investigation of the carbohydrate/DBU cocatalyzed enantioselective diboration of alkenes is presented. These studies provide an understanding of the origin of stereoselectivity and also reveal a strategy for enhancing reactivity and broadening the substrate scope.

A new air-stable catalyst for the oxidative dehydrogenation of benzylic alcohols under ambient conditions has been developed. The synthesis and characterization of this compound and the related monomeric and dimeric V­(IV)- and V­(V)-pinF (pinF = perfluoropinacolate) complexes are reported herein. Monomeric V­(IV) complex (Me4N)2[V­(O)­(pinF)2] (1) and dimeric (μ-O)2-bridged V­(V) complex (Me4N)2[V2(O)2(μ-O)2(pinF)2] (3a) are prepared in water under ambient conditions. Monomeric V­(V) complex (Me4N)­[V­(O)­(pinF)2] (2) may be generated via chemical oxidation of 1 under an inert atmosphere, but dimerizes to 3a upon exposure to air. Complexes 1 and 2 display a perfectly reversible VIV/V couple at 20 mV (vs Ag/AgNO3), whereas a quasi-reversible VIV/V couple at −865 mV is found for 3a. Stoichiometric reactions of 3a with both fluorenol and TEMPOH result in the formation of (Me4N)2[V2(O)2(μ-OH)2(pinF)2] (4a), which contains two V­(IV) centers that display antiferromagnetic coupling. In order to structurally characterize the dinuclear anion of 4a, {K­(18C6)}+ countercations were employed, which formed stabilizing K···O interactions between the counterion and each terminal oxo moiety and H-bonding between the oxygen atoms of the crown ether and μ-OH bridges of the dimer, resulting in {K­(18C6)}2[V2(O)2(μ-OH)2(pinF)2] (4b). The formal storage of H2 in 4a is reversible and proton-coupled electron transfer (PCET) from crystals of 4a regenerates 3a upon exposure to air over the course of several days. Furthermore, the reaction of 3a (2%) under ambient conditions with excess fluorenol, cinnamyl alcohol, or benzyl alcohol resulted in the selective formation of fluorenone (82% conversion), cinnamaldehyde (40%), or benzaldehyde (7%), respectively, reproducing oxidative alcohol dehydrogenation (OAD) chemistry known for VO x surfaces and demonstrating, in air, the thermodynamically challenging selective oxidation of alcohols to aldehydes/ketones.

The effects of Lewis basic phosphoramides on the aggregate structure of t-BuLi have been investigated in detail by NMR and DFT methods. It was determined that hexamethyl­phosphoramide (HMPA) can shift the equilibrium of t-BuLi to include the triple ion pair (t-Bu–Li–t-Bu)−/HMPA4Li+ which serves as a reservoir for the highly reactive separated ion pair t-Bu–/HMPA4Li+. Because the Li-atom’s valences are saturated in this ion pair, the Lewis acidity is significantly decreased; in turn, the basicity is maximized which allowed for the typical directing effects within oxygen heterocycles to be overridden and for remote sp3 C–H bonds to be deprotonated. Furthermore, these newly accessed lithium aggregation states were leveraged to develop a simple γ-lithiation and capture protocol of chromane heterocycles with a variety of alkyl halide electrophiles in good yields.