Calcium Carbide Looping System for Acetaldehyde Manufacturing from Virtually any Carbon Source

Syntheses and Crystal Structures of Alkaline Earth Metal Hydrogen Acetylides AE(C2H)2 with AE = Ca, Sr, Ba

Crystalline Ba(C2H)2 was obtained by the reaction of elemental barium dissolved in liquid ammonia, forming a blue electride, and acetylene (C2H2) injected into the reaction vial with the electride solution. From the colorless precipitate that was obtained after evaporation of the ammonia, the crystal structure of Ba(C2H)2 was solved and refined using synchrotron powder diffraction data. It crystallizes in the trigonal space group P3̅m1 (no. 164) with Z = 1, all HC2- anions are aligned along [001]. It is the first crystal structure of an alkaline earth metal hydrogen acetylide published up to now, showing a close similarity with the brucite (Mg(OH)2) and CdI2-type structures. For Sr(C2H)2, a product with a significantly reduced crystallinity was obtained, but its powder diffraction pattern makes an isotypic crystal structure very likely. IR/Raman spectroscopic investigations as well as GC analysis of the gases released upon hydrolysis unambiguously confirm the existence of HC2- anions in these compounds. Similar results were obtained for Ca(C2H)2, however this compound is almost completely amorphous. Upon heating Ba(C2H)2 with additional elemental barium to 200 °C in vacuum, highly crystalline BaC2 (I4/mmm, Z = 2) was obtained.

Sustainable application of calcium carbide residue as a filler for 3D printing materials

Industrial activity results in ton-scale production of calcium carbide and generation of a significant amount of calcium carbide residue (CCR), which is often disposed of in the environment as waste. CCR is an active chemical, and rain washes away alkali from sludge, changing the pH of soils and water and damaging the environment. In this work, we explored new opportunities for the utilization of CCR in view of the coming industrial uptake of digital design and additive technologies. Amazingly, CCR can be successfully used as a filler for the modification of 3D printed materials towards the introduction of hybrid organic/inorganic frameworks. A series of commercially available plastics (PLA, ABS, Nylon, PETG, SBS) were successfully used as matrices for CCR-based composite production with high CCR contents up to 28%. Tensile analyses showed increases in tensile strength and Young's modulus of 9% and 60%, respectively. Moreover, in comparison with the pure plastics, the CCR-based materials better maintained the digitally designed shape (lower shrinkage). Importantly, CCR-filled materials are 3D printable, making them very promising components in the building sector. Considering the amount of already available CCR stored in the environment, this material is available in large quantities in the near future for hybrid materials, and anticipated opportunities exist in the additive manufacturing sector. The involvement of CCR in practical composite materials is equally important for environmental protection and reuse of already available multiple-ton wastes.

[13 C+D] Double Labeling with Calcium Carbide: Incorporation of Two Labels in One Step

D-labeling is a valuable tool in advanced synthetic chemistry and pharmacy. However, D-incorporation significantly complicates the identification of products. In fact, D labels are invisible in ¹ H-NMR spectra and cause undesirable splitting in ¹³ C-NMR spectra which decreases the detectable limits. At the same time, ² H-NMR spectra are not effective for precise identification due to low sensitivity and the absence of correlations with ¹ H atoms. Here, ¹³ C-label was considered as an accompanying label for D-label in [¹³ C+D] unit for identification of D-containing sites and to track D-labels. [¹³ C+D]-doubly labeled vinyl derivatives and triazoles were synthesized using ¹³ C-labeled calcium carbide as a source of ¹³ C-label and deuterium oxide as a source of D-label. The reaction occurred in one-step manner accompanied with in situ doubly labeled acetylene formation. Non-labeled, mono-labeled and doubly labeled substrates were isolated in 25-80% yields.

Atom-economical synthesis of 1,2-bis(phosphine oxide)ethanes from calcium carbide with straightforward access to deuterium- and 13C-labeled bidentate phosphorus ligands and metal complexes

Straightforward access to bidentate phosphorus ligands and bis(phosphineoxide)ethanes is described based on atom-economic addition reaction. A practical approach was developed to incorporate 2H and 13C labels using easily available reagents.

Thermal Mapping of Self-Promoted Calcium Carbide Reactions for Performing Energy-Economic Processes

The syntheses of various chemical compounds require heating. The intrinsic release of heat in exothermic processes is a valuable heat source that is not effectively used in many reactions. In this work, we assessed the released heat during the hydrolysis of an energy-rich compound, calcium carbide, and explored the possibility of its usage. Temperature profiles of carbide hydrolysis were recorded, and it was found that the heat release depended on the cosolvent and water/solvent ratio. Thus, the release of heat can be controlled and adjusted. To monitor the released heat, a special tube-in-tube reactor was assembled using joining part 3D-printed with nylon. The thermal effect of the reaction was estimated using a thermoimaging IR monitor. It was found that the kinetics of heat release are different when using mixtures of water with different solvents, and the maximum achievable temperature depends on the type of solvent and the amount of water and carbide. The possibility of using the heat released during carbide hydrolysis to initiate a chemical reaction was tested using a hydrothiolation reaction—the nucleophilic addition of thiols to acetylene. In a model experiment, the yield of the desired product with the use of heat from carbide hydrolysis was 89%, compared to 30% in this intrinsic heating, which was neglected.

3D Printing to Increase the Flexibility of the Chemical Synthesis of Biologically Active Molecules: Design of On-Demand Gas Generation Reactors

The development of new drugs is accelerated by rapid access to functionalized and D-labeled molecules with improved activity and pharmacokinetic profiles. Diverse synthetic procedures often involve the usage of gaseous reagents, which can be a difficult task due to the requirement of a dedicated laboratory setup. Here, we developed a special reactor for the on-demand production of gases actively utilized in organic synthesis (C2H2, H2, C2D2, D2, and CO2) that completely eliminates the need for high-pressure equipment and allows for integrating gas generation into advanced laboratory practice. The reactor was developed by computer-aided design and manufactured using a conventional 3D printer with polypropylene and nylon filled with carbon fibers as materials. The implementation of the reactor was demonstrated in representative reactions with acetylene, such as atom-economic nucleophilic addition (conversions of 19-99%) and nickel-catalyzed S-functionalization (yields 74-99%). One of the most important advantages of the reactor is the ability to generate deuterated acetylene (C2D2) and deuterium gas (D2), which was used for highly significant, atom-economic and cost-efficient deuterium labeling of S,O-vinyl derivatives (yield 68-94%). Successful examples of their use in organic synthesis are provided to synthesize building blocks of heteroatom-functionalized and D-labeled biologically active organic molecules.

Sustainable Hydrogenation of Vinyl Derivatives Using Pd/C Catalysts

The hydrogenation of unsaturated double bonds with molecular hydrogen is an efficient atom-economic approach to the production of a wide range of fine chemicals. In contrast to a number of reducing reagents typically involved in organic synthesis, hydrogenation with H2 is much more sustainable since it does not produce wastes (i.e., reducing reagent residues). However, its full sustainable potential may be achieved only in the case of easily separable catalysts and high reaction selectivity. In this work, various Pd/C catalysts were used for the liquid-phase hydrogenation of O-, S-, and N-vinyl derivatives with molecular hydrogen under mild reaction conditions (room temperature, pressure of 1 MPa). Complete conversion and high hydrogenation selectivity (>99%) were achieved by adjusting the type of Pd/C catalyst. Thus, the proposed procedure can be used as a sustainable method for vinyl group transformation by hydrogenation reactions. The discovery of the stability of active vinyl functional groups conjugated with heteroatoms (O, S, and N) under hydrogenation conditions over Pd/C catalysts opens the way for many useful transformations.

Understanding the solubilization of Ca acetylide with a new computational model for ionic pairs

The unique reactivity of the acetylenic unit in DMSO gives rise to ubiquitous synthetic methods. We theoretically consider CaC2 solubility and protolysis in DMSO and formulate a strategy for CaC2 activation in solution-phase chemical transformations. For this, we use a new strategy for the modeling of ionic compounds in strongly coordinating solvents combining Born-Oppenheimer molecular dynamics with the DFTB3-D3(BJ) Hamiltonian and static DFT computations at the PBE0-D3(BJ)/pob-TZVP-gCP level. We modeled the thermodynamics of CaC2 protolysis under ambient conditions, taking into account its known heterogeneity and considering three polymorphs of CaC2. We give a theoretical basis for the existence of the elusive intermediate HC[triple bond, length as m-dash]C-Ca-OH and show that CaC2 insolubility in DMSO is of thermodynamic nature. We confirm the unique role of water and specific properties of DMSO in CaC2 activation and explain how the activation is realized. The proposed strategy for the utilization of CaC2 in sustainable organic synthesis is outlined.