Evaluation and identification of chemical migrants leached from baby food pouch packaging

Multilayer plastic pouch (MLPP) has an estimated 9% annual increase of market growth. However, the migrants it can introduce to food has not yet been systematically studied. A total of 79 MLPPs for baby food were purchased from major retail outlets in Australia. The methodology for testing chemical migration followed the design of previous studies using four types of selected simulants according to the European Committee Regulation No. 10/2011 method. Four bisphenols and five phthalic acid diesters (PAEs) were detected, including the ones known for endocrine disrupting effect in human. Three intentionally added and 23 non-intentionally added substances (NIAS) were tentatively identified through a suspect screening procedure. Out of the 23 NIAS, neopentyl glycol - phthalic acid - 1,6-hexanediol - phthalic acid oligomer was identified for the first time with MLPP. A further two NIAS were detected for the first time in baby food related products. For 40% of the pouches where adipic acid - diethylene glycol was detected, the estimated exposure from consuming one pouch of food per day may exceed the threshold of toxicological concern established based on the Cramer classification.

Catalytic Production of Functional Monomers from Lysine and Their Application in High-Valued Polymers

Lysine is a key raw material in the chemical industry owing to its sustainability, mature fermentation process and unique chemical structure, besides being an important nutritional supplement. Multiple commodities can be produced from lysine, which thus inspired various catalytic strategies for the production of these lysine-based chemicals and their downstream applications in functional polymer production. In this review, we present a fundamental and comprehensive study on the catalytic production process of several important lysine-based chemicals and their application in highly valued polymers. Specifically, we first focus on the synthesis process and some of the current industrial production methods of lysine-based chemicals, including ε-caprolactam, α-amino-ε-caprolactam and its derivatives, cadaverine, lysinol and pipecolic acid. Second, the applications and prospects of these lysine-based monomers in functional polymers are discussed such as derived poly (lysine), nylon-56, nylon-6 and its derivatives, which are all of growing interest in pharmaceuticals, human health, textile processes, fire control and electronic manufacturing. We finally conclude with the prospects of the development of both the design and synthesis of new lysine derivatives and the expansion of the as-synthesized lysine-based monomers in potential fields.

Changes in Number and Antibacterial Activity of Silver Nanoparticles on the Surface of Suture Materials during Cyclic Freezing

This article presents the results of the 10-fold cyclic freezing (−37.0 °C) and thawing (0.0 °C) effect on the number and size range of silver nanoparticles (AgNPs). AgNPs were obtained by the cavitation-diffusion photochemical reduction method and their sorption on the fiber surface of various suture materials, perlon, silk, and catgut, was studied. The distribution of nanoparticles of different diameters before and after the application of the cyclic freezing/thawing processes for each type of fibers studied was determined using electron microscopy. In general, the present study demonstrates the effectiveness of using the technique of 10-fold cyclic freezing. It is applicable to increase the absolute amount of AgNPs on the surface of the suture material with a simultaneous decrease in the size dispersion. It was also found that the application of the developed technique leads to the overwhelming predominance of nanoparticles with 1 to 15 nm diameter on all the investigated fibers. In addition, it was shown that after the application of the freeze/thaw method, the antibacterial activity of silk and catgut suture materials with AgNPs was significantly higher than before their treatment by cyclic freezing.

Highly efficient Ti-catalyst for deoxygenative reduction of esters at ambient conditions: experimental and mechanistic insights from DFT Study

In this paper, we report the synthesis of dianionic amidophosphineborane–supported titanium chloride [{Ph2P(BH3)N}2C6H4}TiCl2] (1) and TiIV alkyl complex [{Ph2P(BH3)N}2C6H4}Ti(CH2SiMe3)2] (2) using salt metathesis reaction. The TiIV complex 1 was obtained...

Alkali and Alkaline Earth Metal Complexes as Versatile Catalysts for Ring-Opening Polymerization of Cyclic Esters

Biodegradable polyesters such as poly(ϵ-caprolactone) (PCL) and poly(lactic acid) (PLA) have been considered for use in several areas, such as drug delivery devices, sutures, tissue engineering, and GBR membranes, due to its bio-renewability, biodegradability, and biocompatibility. Several synthetic techniques for the preparation of polyesters have been reported in the literature, amongst which the ring-opening polymerization (ROP) of cyclic esters is the most efficient. A convenient approach to access iso-selective PLAs is polymerization of racemic lactide (rac-LA), which shows excellent stereoregularity without the need for costly chiral auxiliaries or ligands. In this personal account, we review a series of methods that have been practiced to the synthesis of biodegradable polyesters from various cyclic monomers using alkali and alkaline earth metal complexes as efficient catalysts.

Alkaline Earth Metal-Mediated Highly Iso-selective Ring-Opening Polymerization of rac-Lactide

Alkaline earth (Ae) metal complexes of the aminophosphine borane ligand are highly active and iso-selective catalysts for the ring-opening polymerization (ROP) of rac-lactide (LA). The polymerization reactions are well controlled and produce polylactides with molecular weights that are precise and narrowly distributed. Kinetic studies reveal that the ROP of rac-LA catalyzed by all Ae metal complexes had a first-order dependency on LA concentration as well as catalyst concentration. A plausible reaction mechanism for Ae metal complex-mediated ROP of rac-LA is discussed, based on controlled kinetic experiments and molecular chain mobility.

Highly Chemoselective Hydroboration of Alkynes and Nitriles Catalyzed by Group 4 Metal Amidophosphine-Borane Complexes

We report a series of titanium and zirconium complexes supported by dianionic amidophosphine-borane ligands, synthesized by amine elimination and salt metathesis reactions. The Ti^IV complex [{Ph₂P(BH₃)N}₂C₆H₄Ti(NMe₂)₂] (1) was obtained by the reaction between tetrakis-(dimethylamido)titanium(IV) and the protic aminophosphine-borane ligand [{Ph₂P(BH₃)NH}₂C₆H₄] (LH2) at ambient temperature. Both the heteroleptic zirconium complexes-[η⁵-(C₅H₅)₂Zr{Ph₂P(BH₃)N}₂C₆H₄] (2) and [[{Ph₂P(BH₃)N}₂C₆H₄]ZrCl₂] (3)-and the homoleptic zirconium complex [[{Ph₂P(BH₃)N}₂C₆H₄]₂Zr] (4) were obtained in good yield by the salt metathesis reaction of either zirconocene dichloride [η⁵-(C₅H₅)₂ZrCl₂] or zirconium tetrachloride with the dilithium salt of the ligand [{Ph₂P(BH₃)NLi}₂C₆H₄] (LLi2), which was prepared in situ. The molecular structures of the complexes 1, 2, and 4 in their solid states were confirmed by single-crystal X-ray diffraction analysis. Of these complexes, only titanium complex 1 acts as an effective catalyst for the facile hydroboration of terminal alkynes, yielding exclusive E-isomers. The hydroboration of organic nitriles yielded diborylamines with a broad substrate scope, including broad functional group compatibility. The mechanism of hydroboration occurs through the formation of titanium hydride as an active species.