Iron Catalyzed Synthesis and Chemical Recycling of Telechelic, 1,3-Enchained Oligocyclobutanes

Closed-loop recycling offers the opportunity to help mitigate plastic waste through reversible polymer construction and deconstruction. While examples of the chemical recycling polymers are known, few have been applied to materials derived from abundant commodity olefinic monomers that are the building blocks of ubiquitous plastic resins. Here we describe a [2+2] cycloaddition oligomerization of 1,3-butadiene to yield a previously unrealized telechelic microstructure of (1,n’-divinyl)oligocyclobutane. This material is thermally stable, has stereoregular segments arising from chain-end control, and exhibits high crystallinity even at low molecular weight. Exposure of the oligocyclobutane to vacuum in the presence of the pyridine(diimine) iron precatalyst used to synthesize it resulted in deoligomerization to generate pristine butadiene, demonstrating a rare example of closed-loop chemical recycling of an oligomeric material derived from a commodity hydrocarbon feedstock.

Download Full-text

Organocatalyzed closed-loop chemical recycling of thermo-compressed films of poly(ethylene furanoate)

Polymer Chemistry ◽

10.1039/d0py01623c ◽

2021 ◽

Author(s):

Elena Gabirondo ◽

Beatriz Melendez-Rodriguez ◽

Carmen Arnal ◽

Jose M. Lagaron ◽

Antxon Martínez de Ilarduya ◽

...

Keyword(s):

Closed Loop ◽

Chemical Recycling ◽

Thermally Stable ◽

Poly Ethylene

Poly(ethylene furanoate) (PEF) films were first produced using thermo-compression. Thereafter, the chemical recyclability was demonstrated in the presence of a thermally stable organocatalyst followed by its repolymerization.

Download Full-text

Biologically active ion exchange (BIEX) for NOM removal and membrane fouling prevention

Water Science & Technology Water Supply ◽

10.2166/ws.2017.016 ◽

2017 ◽

Vol 17 (4) ◽

pp. 1178-1184 ◽

Cited By ~ 3

Author(s):

M. Schulz ◽

J. Winter ◽

H. Wray ◽

B. Barbeau ◽

P. Bérubé

Keyword(s):

Molecular Weight ◽

Biological Activity ◽

Ion Exchange ◽

Membrane Fouling ◽

Building Blocks ◽

Biologically Active ◽

Low Molecular Weight ◽

Effective Removal ◽

Pre Treatment ◽

The Impact

The natural organic matter (NOM) removal efficiency and regeneration behavior of ion-exchange filters with promoted biological activity (BIEX) was compared to operation where biological activity was suppressed (i.e. abiotic conditions). The impact of BIEX pre-treatment on fouling in subsequent ultrafiltration was also investigated. Biological operation enhanced NOM removal by approximately 50% due to an additional degradation of smaller humic substances, building blocks and low molecular weight acids. Promotion of biological activity significantly increased the time to breakthrough of the filters and, therefore, is expected to lower the regeneration frequency as well as the amount of regenerate of which to dispose. Pre-treatment using BIEX filters resulted in a significant decrease in total and irreversible fouling during subsequent ultrafiltration. The decrease was attributed to the effective removal of medium and low molecular weight NOM fractions. The results indicate that BIEX filtration is a robust, affordable and easy-to-operate pre-treatment approach to minimize fouling in ultrafiltration systems and enhance the quality of the produced permeate.

Download Full-text

Cavity-containing supramolecular gels as a crystallization tool for hydrophobic pharmaceuticals

Chemical Communications ◽

10.1039/c6cc04037c ◽

2016 ◽

Vol 52 (66) ◽

pp. 10113-10116 ◽

Cited By ~ 29

Author(s):

Lena Kaufmann ◽

Stuart R. Kennedy ◽

Christopher D. Jones ◽

Jonathan W. Steed

Keyword(s):

Molecular Weight ◽

Building Blocks ◽

Low Molecular Weight ◽

Supramolecular Gels

We present two approaches to low-molecular-weight supramolecular gels bearing hydrophobic cavities based on calixarene-containing building blocks.

Download Full-text

Efficient synthesis of the nonamannoside residue of high mannose glycoproteins

Canadian Journal of Chemistry ◽

10.1139/v05-066 ◽

2005 ◽

Vol 83 (6-7) ◽

pp. 693-701 ◽

Cited By ~ 7

Author(s):

Lu Jiang ◽

Tak Hang Chan

Keyword(s):

Molecular Weight ◽

Polyethylene Glycol ◽

Key Words ◽

Building Blocks ◽

Polymer Support ◽

Low Molecular Weight ◽

Oligosaccharide Synthesis ◽

Efficient Synthesis ◽

Solution Synthesis ◽

High Mannose

An efficient synthesis of the nonamannoside residue 1 of high mannose glycoproteins was achieved using an oligomer-supported solution synthesis with low-molecular-weight polyethylene glycol as the anchor. The synthesis required only five coupling steps from only two monosaccharide building blocks with an overall yield of 12%.Key words: nonamannoside, oligosaccharide synthesis, soluble polymer support synthesis, glycoproteins.

Download Full-text

Synthesis and Acylation of 4-Chloroalkyl-3,4-dihydropyrimidin-2(1H)- ones

Zeitschrift für Naturforschung B ◽

10.5560/znb.2012-0182 ◽

2012 ◽

Vol 67 (9) ◽

pp. 921-924 ◽

Cited By ~ 2

Author(s):

Maksim A. Kolosov ◽

Olesia G. Kulyk ◽

Muataz Al-Ogaili ◽

Valeriy D. Orlov

Keyword(s):

Molecular Weight ◽

Carboxylic Acid ◽

Building Blocks ◽

Low Molecular Weight ◽

One Pot ◽

Acid Anhydrides ◽

Acyl Derivatives

4-Chloroalkyl-3,4-dihydropyrimidin-2(1H)-ones are useful multifunctional 3,4-dihydropyrimidine building blocks with low molecular weight and sufficient solubility, which may be modified selectively by substituents in different positions. Here we propose a simple one-pot protocol for the synthesis of these compounds, which is based on the use of common reagents viz. urea, chloroaliphatic aldehydes and 3-ketoesters. Acylation of 4-chloroalkyl-3,4-dihydropyrimidin-2(1H)-ones by carboxylic acid anhydrides leads to 3-acyl derivatives

Download Full-text

Synthesis and characterization of pH responsive D-glucosamine based molecular gelators

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.10.328 ◽

2014 ◽

Vol 10 ◽

pp. 3111-3121 ◽

Cited By ~ 17

Author(s):

Navneet Goyal ◽

Hari P R Mangunuru ◽

Bargav Parikh ◽

Sonu Shrestha ◽

Guijun Wang

Keyword(s):

Molecular Weight ◽

Building Blocks ◽

Negative Influence ◽

Low Molecular Weight ◽

Ph Responsive ◽

Triggered Release ◽

Self Assembling ◽

Potential Applications ◽

Low Molecular Weight Gelators ◽

Neutral Conditions

Small molecular gelators are a class of compounds with potential applications for soft biomaterials. Low molecular weight hydrogelators are especially useful for exploring biomedical applications. Previously, we found that 4,6-O-benzylidene acetal protected D-glucose and D-glucosamine are well-suited as building blocks for the construction of low molecular weight gelators. To better understand the scope of D-glucosamine derivatives as gelators, we synthesized and screened a novel class of N-acetylglucosamine derivatives with a p-methoxybenzylidene acetal protective group. This modification did not exert a negative influence on the gelation. On the contrary, it actually enhanced the gelation tendency for many derivatives. The introduction of the additional methoxy group on the phenyl ring led to low molecular weight gelators with a higher pH responsiveness. The resulting gels were stable at neutral pH values but degraded in an acidic environment. The release profiles of naproxen from the pH responsive gels were also analyzed under acidic and neutral conditions. Our findings are useful for the design of novel triggered release self-assembling systems and can provide an insight into the influence of the the structure on gelation.

Download Full-text

Development of Natural-Drugs-Based Low-Molecular-Weight Supramolecular Gels

Gels ◽

10.3390/gels7030105 ◽

2021 ◽

Vol 7 (3) ◽

pp. 105

Author(s):

Xiaoyi Feng ◽

Yuning Luo ◽

Fangjie Li ◽

Xueting Jian ◽

Yang Liu

Keyword(s):

Molecular Weight ◽

Self Assembly ◽

Water Solubility ◽

Drug Loading ◽

Building Blocks ◽

Low Molecular Weight ◽

Assembly Mechanism ◽

Supramolecular Gels ◽

Potential Applications ◽

Natural Drugs

Natural small molecular drugs with excellent biocompatibility, diverse pharmacological activities, and wide sources play an increasingly important role in the development of new drug and disease treatment. In recent years, the utilization of paclitaxel, camptothecin, rhein, curcumin, and other natural small molecular drugs with unique rigid backbone structures and modifiable multiple sites as building blocks to form gels by self-assembly has attracted widespread attention. The obtained low-molecular-weight supramolecular gel not only retains the general characteristics of the gel but also overcomes the shortcomings of natural drugs, such as poor water solubility and low bioavailability. It has the advantages of high drug loading, low toxicity, and outstanding stimulus responsiveness, which is widely used in biomedical fields. Here, we provided a comprehensive review of natural-drugs-based low-molecular-weight supramolecular gels reported in recent years and summarized their assembly mechanism, gel structure, gel properties, and potential applications. It is expected to provide a reference for further research of natural-drugs-based supramolecular gels.

Download Full-text