Resins from furanic derivatives

Furan resins. Thermosets manufactured from furan derivatives such as furfural, furfuryl alcohol, tetrahydrofurfuryl alcohol. Applications foundry resins and core binders, acid-proof coatings, putties. 

Uses. Furfural is primarily a chemical feedstock for a number of monomeric compounds and resins. One route produces furan by decarbonylation. Tetrahydrofuran is derived from furan by hydrogenation. Polytetramethylene ether glycol [25190-06-1] is manufactured from tetrahydrofuran by a ring opening polymeri2ation reaction. Another route (hydrogenation) produces furfuryl alcohol, tetrahydrofurfuryl alcohol, 2-methylfuran, and 2-methyltetrahydrofuran. A variety of proprietary synthetic resins are manufactured from furfural and/or furfuryl alcohol. Other... 

Furan derivatives remained commercially insignificant until about 1920, when furfural was prepared in bulk from acid digestion of the pentosans of oat hulls and corn cobs for use as an industrial solvent and in the preparation of synthetic resins. How this change was wrought is one of the epics of industrial chemistry (B-56MI31000). 

Furans. The last statement is certainly true of furans derived from sugars (142,143), particularly furfural and furfuryl alcohol, which is readily derived from furfural (144)- Dr. McKillip of QO Chemicals discusses furan resin chemistry and furan polymers in Chapter 29. Dr. Stanford and his colleagues at the University of Manchester Institute of Science and Technology discuss the use of a diisocyanate derived from furfural for polyurethane production in Chapter 30. 

Polymers containing heterocycles in the backbone include a variety of compounds, as the diversity of heterocyclic molecules is quite large. The polymers from this class may contain groups derived from furan, thiophene, pyrrole, isoindole, benzimidazole, benzothiazole, benzoxazole, quinoxaline, etc. Macromolecules with a ladder backbone containing, for example, a phenoxazine unit in their structure also are known. Amino thermosetting resins from melamine can be considered as polymers containing heterocycles in their structure. 

In the above condensation resist designs, the phenolic resin offers a reaction site as well as base solubility. Self-condensation of polymeric furan derivatives has been utilized as an alternative crosslinking mechanism for aqueous base development (Fig. 126) [375]. The copolymer resist is based on poly[4-hydroxy-styrene-co-4-(3-furyl-3-hydroxypropyl)styrene], which was prepared by radical copolymerization of the acetyl-protected furan monomer with BOCST followed by base hydrolysis. The furan methanol residue, highly reactive toward electrophiles due to a mesomeric electron release from oxygen that facilitates the attack on the ring carbons, readily yields a stable carbocation upon acid treatment. Thus, the pendant furfuryl groups serve as both the latent electrophile and the nucleophile. Model reactions indicated that the furfuryl carbocation reacts more preferentially with the furan nucleus than the phenolic functionality. 

Many biomass pyrolysis processes convert 55%-65% of dry biomass to a very inexpensive pyrolysis oil (1-3). Costs of the oils will range from 0.02- 0.08/lb of oil, depending on the biomass feedstock cost ( 10- 40/dry ton biomass). Therefore, these inexpensive oils, rich in phenolic fractions, acids, and furan-derivatives could be feedstocks for further upgrading or could be used because of their reactivity, in applications such as thermosetting resins and other wood-bonding methods. One of the... 

Around 60 elemanes are known at present and some of these have been isolated from woody tissues. (-)-Elemol (206) was first isolated in 1907 (350) from Manila elemi oil obtained from the oleoresin of Canarium luzonicum. (-)-)ff-Elemene (209) (238, 396), shyobunone (210) (419), and a few related elemanes occur in the essential oil from rhizomes of Acorus calamus, Resin from Ferula spp. (Galbanum resin) contains 10-epi-elemol (211) (391). The furane derivative, curzerenone (212), has been isolated from rhizomes of Curcuma zedoaria (195). The majority of presently known elemanes have a lactone ring and are known as elemanolides they have been recently rewiewed (146). Callitrin (213) is an example of an elemanolide that has been isolated from the heartwood of Callitris col-umellaris (59). 

There are two basic types of processes used to make CAMCs. The first is chemical vapor infiltration (CVI). CVI is a process in which gaseous chemicals are reacted or decomposed, depositing a solid material on a fibrous preform. In the case of CAMCs, hydrocarbon gases like methane and propane are broken down, and the material deposited is the carbon matrix. The second class of processes involves infiltration of a preform with polymers or pitches, which are then converted to carbon by pyrolysis (heating in an inert atmo-sphere). After pyrolysis, the composite is heated to high temperatures to graphitize the matrix. To minimize porosity, the process is repeated untU a satisfactory density is achieved. This is called densification. Common matrix precursors are phenolic and furan resins, and pitches derived from coal tar and petroleum. 

Other furan compounds, best derived from furfural, are of interest although commercial volumes are considerably less than those of furfural, furfuryl alcohol, furan, or tetrahydrofurfuryl alcohol. Some of these compounds are stiU in developmental stages. Apphcations include solvents, resin intermediates, synthetic mbber modifiers, therapeutic uses, as well as general chemical intermediates. 

Euran Furan resins are thermosetting polymers derived from furfuryl alcohol and Furfural. The cure must be carefully controlled to avoid the formation of blisters and delaminations. To obtain optimum strength and corrosion resistance, furan composites must undergo a postcure schedule at carefully selected temperatures depending upon the laminate thickness. Equipment made with furan resins exhibits excellent resistance to solvents and combinations of acids and solvents. These resins are not for use in strong oxidizing environments. 

Benzo[6 ]furan (2), usually called simply benzofuran, was first prepared by Perkin, who obtained it from coumarin as in Scheme 2 and (not understanding its constitution) called it coumarone, an unsuitable name that still survives in the term coumarone resin , for the compound is now valued for copolymerization purposes. Later the compound was isolated by distillation of bituminous coal, which is also a source of several methyl and hydroxy derivatives and of dibenzofuran (the name diphenylene oxide is now discarded) <75AHC(18)337>. 

All of the studies mentioned are directed to lignins derived from pulp and paper manufacture. This requires that a traditionally conservative pulp and paper industry embark on further development as a chemical producer. However, Helena Chum and her colleagues (Chapter 11) derive their phenolics from lignin by fast pyrolysis of wood rather than as byproducts from the pulp and paper industry. Opportunities might be better for development of adhesives from a chemical manufacturer drawing on waste wood as a raw material much the same as has developed in the production of furan resins derived from agricultural residues described by Bill McKillip (Chapter 29). 

Furan polymers are based on furfuryl alcohol, which is derived from agricultural residues such as corncobs, rice hulls, oat hulls, or sugar cane bagasse. The furan prepolymer is usually cross-linked with furfuryl alcohol, furfuraldehyde, or formaldehyde to yield thermosetting polymers, highly resistant to most aqueous acidic or basic solutions and strong solvents such as ketones, aromatics, and chlorinated compounds. The important characteristic of furan resins is their ability to be stored for long periods of time (up to 5 years), even at low temperatures. 

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