Research into the Process of Preparing an Additive for Drywall Based on Polymethylene Naphthalenesulfonate

In the technology of synthesis of an additive for drywall based on polymethylene naphthalenesulfonate, it is proposed to carry out an additional stage - the Cannizzaro reaction, which allows reducing the mass fraction of residual formaldehyde. In the process of experimental studies, the effect of the additive on the plasticizing properties of the gypsum dough was revealed.

Smart Food Packaging Designed by Nanotechnological and Drug Delivery Approaches

This paper offers a general view of the solutions that are able to confer bioactivity to the packaging materials, especially antimicrobial and antioxidant activity. These properties can be induced by the nature of the polymers blend or due to the addition of ternary components from natural agents (essential oils or other extracts) to synthetic organic and inorganic agents, including nanoparticles with a broad antimicrobial activity such as metals (e.g., Ag, Au, Cu) or metal oxide (e.g., TiO2, ZnO) nanoparticles, and even bacterial cells such as probiotics. Many times, these components are synergistically used, each of them assuring a specific role or potentiating the role of the other components. The antimicrobial activity can be induced due to the applied coatings or due to the whole bulk material. Along with an increasing food stability which means a longer shelf-life some smart packaging can be exploited in order to highlight the freshness of the food. These act as a sensor (usually pH sensitive but also other mechanisms can be exploited such as aggregation/agglomeration of AuNPs leading to color change or even aldehyde-specific reactions such as the Cannizzaro reaction), and thus, consumers can be confident about the freshness of the food, especially perishable food such as seafood or fish.

Kraft lignin reaction with paraformaldehyde

Lignin is the second most abundant biopolymer and will be an important source for carbon-containing compounds in the future. Based on their similar phenolic structures, lignin has great potential to become a valuable substitute for phenol in phenol-formaldehyde resin adhesives. To meet this aim, the sodium hydroxide (NaOH)-catalyzed reaction of kraft lignin with formaldehyde was studied by using paraformaldehyde (PFA) as a formaldehyde source. The advantage of using PFA, the solid polymer of formaldehyde, is the simple composition of the depolymerized solution. According to the results of differential scanning calorimetry (DSC), the lignin reaction was found to require a high NaOH concentration in order for the reaction with PFA to proceed at reasonably low temperatures compared to the curing temperature of phenol-formaldehyde resins (approximately 150°C). On the other hand, high alkalinity conditions are known to favor the disproportionation of formaldehyde to formic acid and methanol. Due to the moderate reactivity of lignin, the Cannizzaro reaction can compete with the methylolation reaction of lignin. Based on the results of 13C, 31P and 1H-13C heteronuclear single quantum correlation nuclear magnetic resonance (HSQC NMR), methylolation was found to be the main reaction occurring in the lignin-formaldehyde reaction.

Theoretical DFT study of Cannizzaro reaction mechanism: A mini perspective

In regards to the Cannizzaro reaction and its peculiar mechanism, some researchers have presented a free radical mechanism for the Cannizzaro reaction, while others have found that it is feasible through an ionic mechanism, but the actual mechanism has not been finalized yet. The researchers have given the proof of both the mechanisms through their papers published. Actually, Cannizzaro reaction may occur through both mechanisms depending on both molecular structure and different conditions which are yet to be explained. Recently published papers describe that free radical mechanism occurs only in a heterogeneous medium, while an ionic mechanism occurs in a homogeneous medium. We revealed no explanation of the molecular structure-based reason, responsible for a radical or an ionic mechanism. The present paper reviews not only homogeneous/heterogeneous medium conditions but also molecular structure-based facts, which may be responsible for the Cannizzaro reaction to occur through the radical or ionic mechanism, and that may be acceptable to the scientific society. Besides, Density Functional Theory study using Gaussian software was also involved in the explanation of the molecular structure, responsible for one of the two mechanisms. Also, the present paper specifies all points related to future perspectives on which additional studies are required to understand the actual mechanism with a definite molecular structure in the different reaction media.