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

Production of Acetylene from Viable Feedstock: Promising Recent Approaches

The potential of acetylene is extremely high both in chemical industry and synthetic applications due to unsaturated nature and the smallest active C≡C unit. The production of many essential necessities is originated from acetylene; however, the formation of acetylene molecule requires a lot of energy. Currently, the access to acetylene is based on coal processing, methane reforming and calcium carbide hydrolysis. Recently, extensive research has been done to decrease the cost of acetylene. In this review, the routes to acetylene were highlighted, considering the energy consumption in kW ⋅ h/t of the product to evaluate the best approach. Since energy prices depend on various regions, the cost of the product is complicated. The manufacturing of acetylene is usually accompanied by formation of by-products, which may be valuable or not. The review should help to identify current status and not overlook promising approaches.

Calcium Carbide (CaC2) as a C2-Synthon by Mechanochemistry

Mechanochemical reactions by ball milling have opened new avenues in chemical synthesis. Particularly, mechanochemistry has facilitated the reaction of insoluble materials to simplify stablished synthetic protocols and develop new ones. One notable application involves the use of calcium carbide (CaC2) as a C2-synthon through mechanochemistry, which has offered a more practical alternative to incorporate C2-units compared to the conventional use of highly flammable gaseous acetylene. For example, by ball milling, the acetylenic anions [C2]2- found in CaC2 have been harnessed for the synthesis of diverse functional carbon materials as well as discrete organic molecules. This Concept aims to contribute to the conceptualization of this innovative approach while highlighting both its advantages and the challenges inherent in the use of CaC2.

Ligand Control of Copper-Mediated Cycloadditions of Acetylene to Azides: Chemo- and Regio-Selective Formation of Deutero- and Iodo-Substituted 1,2,3-Triazoles

The participation of σ-monocopper and σ-bis-copper acetylide in mechanistic pathways for copper-catalyzed cycloaddition (CuAAC) reactions of acetylene with azides was probed by analysis of deuterium distributions in the 1,2,3-triazole product formed by deuterolysis of initially formed mono- and bis-copper triazoles. The results show that, when Cu(Phen)(PPh3)2NO3 is used as the catalyst for reactions of acetylene with azides in DMF/D2O, 1-substituted-5-deutero-1,2,3-triazoles are generated selectively. This finding demonstrates that the Cu(Phen)(PPh3)2NO3-catalyzed cycloadditions utilize monocopper acetylide as the substrate and produce 5-copper-1,2,3-triazoles initially. Conversely, when DBU or Et3N is the copper ligand, the process takes place through initial formation and cycloaddition of bis-copper acetylide to produce 4,5-bis-copper-triazole, which reacts with D2O to form the corresponding 4,5-bis-deutero-triazole. Moreover, when C2D2 is used as the substrate, Cu(Phen)(PPh3)2NO3 as the Cu ligand, and H2O/DMF as the solvent, mono-C4-deutreo 1,2,3-triazoles are generated in high yields and excellent levels of regioselectivity. Lastly, CuAAC reactions of acetylene with azides, promoted by CuCl2·2H2O and NaI, yield 4,5-diiodo-1,2,3-triazoles with moderate to high efficiencies.

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.