Preface

The modern world is moving towards sustainable development and furan is a key material in this transition. Furan is processed from furfural, which is an organic compound obtained from biomass feedstock. Thus, furan is a green and environmentally friendly material. It is used to produce pharmaceuticals, resin, agrochemicals, and lacquers. It is an important starting material for a variety of industries for the preparation of many useful products. This book presents comprehensive information on furan and its derivatives.

Chapter 1 presents recent developments in catalytic enantioselective reactions of furans derived from biomass, such as unsubstituted furan, 2-methylfuran, 2,5-dimethylfuran, and furfural. Although several review articles have dealt with the Diels-Alder reactions of furans, there have been no articles highlighting enantioselective versions. The resulting products derived from the catalytic enantioselective reaction of furan are often found as core structures in natural products and pharmaceuticals with important pharmacological activities. After recognizing the valuable skeleton of chiral furan derivatives, numerous attempts have been made to synthesize them by utilizing enantioselective cycloaddition reactions, Friedel-Craft reactions, and nucleophilic addition reactions. Enantioselective cyclization reactions using furans as the 4π diene component provided chiral dihydrofuran derivatives. On the other hand, Friedel-Craft and nucleophilic addition reactions served various furan derivatives with the chiral carbon atom in the a-position.

Chapter 2 examines the synthesis of the compound 2-[2-(4-methylphenylamino)- 4-phenylthiazol-5-yl]benzofuran prepared from 1-(4-methylphenyl)-3- (N-phenylbenzimidoyl)thiourea and 2-(2-bromoacetyl)benzofuran in the presence of triethylamine and characterized by FTIR, NMR, and mass spectra. Density functional theory (DFT) computations were adopted for the geometric optimization of this compound to evaluate the Mulliken atomic charge distribution, HOMO-LUMO energy gap, and vibrational analysis. The titled compound induced G1 cell cycle arrest, which is regulated by CDK2 in cancer cells. Therefore, we used molecular modelling to study in silico the possible inhibitory effect as a mechanism of this compound as anticancer agents (PDB code:2KW6, 6DL7, 6VJO, 6WMW, 7LAE). The molecular docking study revealed that the compound was most effective in inhibiting CDk2 cancer cells.

Chapter 3 reports on the synthesis of new α,α-diaminoester and α,α-diamino acid derivatives, as 2-benzamido-2-[(tetrahydro-furan-2-ylmethyl)amino] acetic acid through alkaline hydrolysis reaction of corresponding N-benzoylated methyl α,α-diamino ester. The α,α-diaminoester derivative was synthesized by nucleophilic substitution of methyl α-azido glycinate N-benzoylated with 2-tetrahydrofuran-2-ylmethan-amine. The structure of these products was established on the basis of NMR spectroscopy (1 H, 13C) and MS data.

Chapter 4 describes new reactive hotmelt (RHM) adhesives based on thermally reversible Diels-Alder networks comprising multifunctional furan and maleimide prepolymers. The prepolymer mixture is easy to apply in bulk from the melt

and after application to the substrates, the adhesive undergoes polymerization at room temperature resulting in crosslinked bonds. Due to their thermoplastic nature and low melt viscosity at hot melt application temperatures, the adhesives provide processing properties similar to moisture-cured polyurethanes (PURs). The technology is isocyanate-free and does not require moisture to initiate the crosslinking. Bonding and tensile properties of the RHM adhesive can be readily tuned by prepolymer design and provide cure rates like those of PUR adhesives. The Diels-Alder adhesives provide versatile adhesion to a variety of substrates and good creep resistance up to the retro temperature. The adhesives show good thermal stability during application and can be recycled multiple times by simple heating/ cooling of the bonds providing similar performance. Several furan and maleimide prepolymers were scaled up to multi-Kg quantities to demonstrate the potential for industrial scalability. The results demonstrate that furan-maleimide reversible chemistry can be used for RHM application as a more sustainable alternative to conventional moisture curing PURs, which tend to contain harmful residual isocyanate monomers.

Chapter 5 discusses the evolution of NOx precursors NH3 and HCN from pyrolysis of furfural residue (FR). The pyrolysis process was carried out in a thermogravimetric analyzer (TGA) coupled to a Fourier-transform infrared (FTIR) spectrometer. The combination revealed insightful information on the evolution of NH3 and HCN. This information allows for better understanding of the characteristics of FR derived from furfural production, especially with regard to NH3 and HCN. Nitrogen is considered a minor component in biomass wastes; in this study nitrogen content is about 0.57%. However, the pollution potential of low-nitrogen content is huge through both direct and indirect processes. Thus, this study presents results on FR pyrolysis in a pure nitrogen environment. At the heating rate of 40ºC/min-1, the only NOx precursor detected was HCN at 713cm-1 as per the database provided by National Institute of Standards and Technology (NIST). NH3 was not detected. The particle size of FR used ranged between 0.15 and 0.25 mm.

Chapter 6 reviews pure furanics, tannin–furanics, and tannin–furanic-furanic humins as fire resistant, environmentally friendly rigid biofoams. More recently, furanic wood adhesives have been developed in which a major furan portion is coupled with either synthetic or bioadhesives. In the case of furanic wood bioadhesives, formulations developed range from being 90% to 100% biosourced. Equally, furanic rigid plastics of considerable mechanical resistance have also been developed and applied in the production of angle-grinder disks and automotive brakes with very encouraging results showing the capacity of these resins to resist to the very high mechanical stresses applied.

Chapter 7 describes furfural, a five-membered heterocyclic aromatic hydrocarbon derivable from acid hydrolysis of sugar cane bagasse, maize cob, rice husk, or any cellulose-containing material. It is useful in the synthesis of a range of specialized chemical products. Its condensation with nitromethane in basic medium yields 2-(2-Nitrovinyl) furan. This functional group (nitrovinyl) has been documented as a potent antimicrobial agent against gram-positive and gram-negative bacteria, with more potency against the gram-positive strains. The reaction of urea and thiourea with furfural yields bisimines-1,3-bis[(*E*)-furan2-yl)methylene] urea, and 1,3-bis[(*E*)-furan-2-yl) methylene]thiourea, respectively. The two compounds are good antimicrobial agents in addition to the latter being a potential dye for wool and cotton fabrics with different hues. Also, the reaction between

**V**

acetophenone and furfural (an aldehyde) in a basic medium yields the chalcone: (*E*)-3-(furan-2-yl)-1-phenylprop-2-ene-1-one. This chalcone has been confirmed as a good antifungal agent and wood-protector against termite attack. Thus, chemical modification of the aldehyde functional group of furfural to nitro, imine, and

**Anish Khan**

King Abdulaziz University, Jeddah, Saudi Arabia

King Abdulaziz University, Jeddah, Saudi Arabia

Hyderabad, Telangana, India

**Salman Ahmad Khan** School of Sciences,

Kannampalayam, India

**M. Ramesh**

**Mohammed Muzibur Rahman** 

**and Abdullah Mohammed Ahmed Asiri**

Maulana Azad National Urdu University,

Kalaignarkarunanidhi Institute of Technology,

Center of Excellence for Advanced Materials Research,

chalcone groups imparted different activities on furfural.

acetophenone and furfural (an aldehyde) in a basic medium yields the chalcone: (*E*)-3-(furan-2-yl)-1-phenylprop-2-ene-1-one. This chalcone has been confirmed as a good antifungal agent and wood-protector against termite attack. Thus, chemical modification of the aldehyde functional group of furfural to nitro, imine, and chalcone groups imparted different activities on furfural.

## **Anish Khan**

Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia

## **Mohammed Muzibur Rahman and Abdullah Mohammed Ahmed Asiri**

King Abdulaziz University, Jeddah, Saudi Arabia

## **Salman Ahmad Khan**

School of Sciences, Maulana Azad National Urdu University, Hyderabad, Telangana, India

## **M. Ramesh**

Kalaignarkarunanidhi Institute of Technology, Kannampalayam, India

Section 1

Furans and Furan Derivatives - Recent Advances

## **Chapter 1**
