Production and purification of anhydrous sodium sulfide

A Tandem Ring Closure and Nitrobenzene Reduction with Sulfide Provides an Improved Route to an Important Intermediate for the Anti-Tuberculosis Drug Candidate Sutezolid

Sutezolid is an in-development thiomorpholine derivative of the FDA-approved tuberculosis (TB) treatment linezolid. Current synthetic routes for preparing sutezolid start with thiomorpholine as a key structural building block; unfortunately, this material was identified as a major cost driver for the API, which will limit the potential uptake of this treatment in lower income regions. In this work, an alternative, lower-cost synthetic strategy to a known p-phenylenediamine intermediate to sutezolid has been demonstrated. The key step in this process is the construction of the thiomorpholine ring by a nucleophilic sulfide ring closure on an activated bis(2-hydroxyethyl)-functionalized aniline, which was in turn made by reaction of 3,4-difluoronitrobenzene and diethanolamine. This sulfide treatment has the added benefit of affecting a Zinin reduction of the nitro functional group, which alleviates the need for the transition metal reduction used in previous routes. After optimization, this key reaction was able to provide the desired aniline intermediate in yields between 65 and 80% and, after a standard charcoal treatment, purity of >94%. Initial demonstrations of the full 3-step strategy were successfully conducted on scales up to 100 g with overall yields of 53-68%. This preliminary work will serve as the foundation for a broader low-cost redesign of the sutezolid synthetic process.

Making the Unfeasible Feasible: Synthesis of the Battery Material Lithium Sulfide via the Metathetic Reaction between Lithium Sulfate and Sodium Sulfide

Lithium sulfide (Li2S) is a highly desired material for advanced batteries. However, its current industrial production is not suitable for large-scale applications in the long run because the process is carbon-emissive, energy-intensive, and cost-ineffective. This article demonstrates a new method that can overcome these challenges by reacting lithium sulfate (Li2SO4) with sodium sulfide. This approach, which seems unfeasible initially because Li2SO4 is barely soluble in ethanol at room temperature, becomes feasible when heated ethanol and an excess amount of Li2SO4 are used. More interestingly, product purification is easier than that in other metathetic reactions, thanks to the poor solubility of Li2SO4. In order to further minimize the overall costs of producing Li2S, the concomitant byproduct LiNaSO4 and the unfinished precursor Li2SO4 are converted into more valuable materials, Li2CO3 and Na2SO4. Moreover, the homemade Li2S is competitive with the commercial Li2S in cathode performance and gains further enhancement when being composited with the Co9S8 catalyst. Thus, this Li2SO4-based metathesis of Li2S has great potential for practical applications.

Low-Cost Preparation of High-Performance Na-B-H-S Electrolyte for All-Solid-State Sodium-Ion Batteries

All-solid-state sodium-ion batteries have the potential to improve safety and mitigate the cost bottlenecks of the current lithium-ion battery system if a high-performance electrolyte with cost advantages can be easily synthesized. In this study, a one-step dehydrogenation-assisted strategy to synthesize the novel thio-borohydride (Na-B-H-S) electrolyte is proposed, in which both raw material cost and preparation temperature are significantly reduced. By using sodium borohydride (NaBH4 ) instead of B as a starting material, B atoms can be readily released from NaBH4 with much less energy and thus became more available to generate thio-borohydride. The synthesized Na-B-H-S (NaBH4 /Na-B-S) electrolyte exhibits excellent compatibility with current cathode materials, including FeF3 (1.0-4.5 V), Na3 V2 (PO4 )3 (2.0-4.0 V), and S (1.2-2.8 V). This novel Na-B-H-S electrolyte will take a place in mainstream electrolytes because of its advantages in preparation, cost, and compatibility with various cathode materials.