Resorcinol replacement

The reactivity of resorcinol with formaldehyde is essential for developing the cohesive strength of the interlayer and its bonding characteristics. Condensed tannins are known to be very reactive with formaldehyde (7-0), so these renewable phenolic polymers are good candidates as resorcinol replacements. Indeed, condensed tannins from wattle and pine bark extracts have been successfully used in cold-setting, wood-laminating adhesives, and the former are used extensively in the commercial production of laminated timbers in South Africa (Pizzi, A., National Timber Research Institute, Pretoria, South Africa, personal communication, 1982) (10-13). 

In the second approach (120), condensed tannins were purified of co-occur-ring carbohydrates and used as resorcinol replacements in a honeymoon system (116) as described previously in use of wattle tannin adhesives. One surface was spread with a commercial phenol-resorcinol-formaldehyde laminating adhesive, to which additional formaldehyde was added. The other surface was spread with pine bark tannin extract in sodium hydroxide solutions. Bonds meeting the requirements of the American Institute of Timber Construction were also obtained using this approach. It was necessary to remove the carbohydrates, however. Addition of the separated carbohydrates at comparatively low levels (about 10%) resulted in bonds with low wood failure. 

Grigsby, W. and Warnes, J. (2004) Potential of tannin extracts as resorcinol replacements in cold cure thermoset adhesives. Eur. J. Wood Wood Prod, 62 (6), 433-438. 

We understand well the interest in using peeling mixtures of different substances so as to combine caustic, toxic, and metabolic effects. This explains the interest in Jessner s solution (a mixture of resorcinol, lactic acid, and sahcyhc acid) Monheit s formula (a version of a modified Jessner s solution with the resorcinol replaced with citric acid) other secret modified phenol formulas and others (Fintsi,Kakowicz,De Rossi Fattaccioli, etc.). 

As polymer chemistry advanced in the 1930s and 1940s, stronger and more durable synthetic adhesives such as early phenol, resorcinol and urea formaldehydes began to supplant natural glues in wood aircraft manufacture. Around this time however, metal began to replace wood as the dominant material for aircraft manufacture. Aerospace adhesives research and development moved on to focus on metals, primarily aluminum, as the substrates of interest. 

A rare example of substitution kinetics at mercury(II) is provided by the adaptation of replacement of coordinated 4-(2-pyridylazo)resorcinol by l,2-cyelohexanediamine-./V,./V,./V,./V,-tetraacetate to analysis for sulfite or thiosulfite (324). 

In view of the utility of the aromatic polyesters and the demonstrated effectiveness of the aromatic polyphosphonates as flame retardants, the combination of these two polymers was chosen for this study. In addition, this system provided a composition in which both copolymers and polymer blends could be prepared with identical chemical compositions. The polyesters were prepared from resorcinol with an 80/20 m/m ratio of iso-phthaloyl and terephaloyl chlorides while the polyphosphonates were resorcinol phenylphosphonate polymers. Copolymerized phosphorus was incorporated by replacement of a portion of the acid chloride mixture with phenylphosphonic dichloride. 

Dimethyl-HeptylResorcinol TET, 23, 77 (1967). According to R. Adams (JACS, 70, 664 (1948), who made this resorcinol back in 1948, it makes a THC 70 times more powerful than the naturally occurring THC when tested on dogs, and is 500 times more potent than natural THC when tested on rats (JMC, 16, 1200 (1973), To come up with the 1,2-dimethyl-heptyl resorcinol, the formula given in the reference must be changed by replacing 2,4-dimethoxy-acetophenone with 3,5-dimethoxy-acetophenone. 

Naphthol-a-aldehyde (p -hydroxy-a-naphthaldehyde). Proceed as for J-resorcylaldehyde except that 20 g. of (3-naphthol replaces the resorcinol. Recrystallise the crude product (20 g.) from water with the addition of a little decolourising carbon the pure aldehyde has m.p. 80-81°. 

Based on this tautometism, certain addition and replacement reactions at the hydroxyl or keto groups can be effected easily as with certain reactions of resorcinol and 2-naphthalenol. Thus, phloroglucinol forms a trioxime with hydroxylamine (120) it forms mono-, di-, and ttiaddition compounds with sodium bisulfite (121) it undergoes the Bucherer reaction with ammonia at room temperature (122) to give at first phloramine... 

The bark extract bonded particleboards met specifications requiring the inherent durability provided by phenolic adhesives. These products are used for floor decking for modular homes, specialized furniture uses, home siding, garage door panels and more recently, as a wall and roof sheathing and single layer floor decking in conventional home construction. Thus, phenol and phenol-resorcinol modified resins can be replaced by a low-cost bark product. This use of bark would be a profitable outlet for bark residues and could lead to virtual independence of the wood particleboard industry from the petrochemical industry. 

Ready conversion of nitro compounds to amines further extends the applicability of the deamination process. For example, the nitro group may be introduced into an aromatic nucleus for the purpose of closing a position to other groups in subsequent steps of a synthetic sequence, and, finally, the nitro group is replaced by hydrogen. This blocking effect is utilized in the preparation of 2-chlororesorcinol, which cannot be obtained by direct chlorination of resorcinol.187... 

Captan [Ar-(trichloromethylthio)-l,2,3,6-tetrahydrophthalimide] reacts with resorcinol with the formation of a condensed ring, l,6-dioxa-6aA4-dithiapentalene as indicated in equation (12). Similar results are obtained when captan is replaced by thiophosgene (72T2183). 

It is worthwhile to review the U.S. market size for the four principal resins currently used in wood-panel products today (4 )- These are phenol-formaldehyde (PF), urea-formaldehyde (UF), melamine-formaldehyde (MF), and resorcinol-formaldehyde (RF) (Table III). When these production figures are compared to the quantities of lignin potentially available (Table II), it is immediately obvious that all wood adhesives could be replaced by only a very small fraction of the lignin produced annually during chemical woodpulping processes. 

Selection of the End-Joint Profile. Because the purpose of this work was to determine whether a portion of the phenol-resorcinol-formaldehyde adhesive used in structural end-joints could be replaced by tannin extracts from southern pine bark, it was necessary to use a structural end-joint profile design. The profile chosen was the design used by many U.S. plants for the manufacture of structural end-joints. A reproduction in natural size with a drawing showing the exact dimensions is shown in Figure 1. 

The purpose of the research described here was to explore the feasibility of using condensed tannins as replacements for resorcinol in RFL-type adhesive... 

The pecan pith extract was the best of the tannin extracts examined in bonding to polyester cord. Pullout forces using this extract to totally replace resorcinol were nearly twice as high as in the standard dip. The purified pine bark extract also gave very good results. One commonality in these two extracts... 

Casein adhesives experienced similar problems. Once the industry recognized that they were not waterproof, as was originally believed, they were rapidly replaced by resorcinols in most structural, cold-set applications where pressure was easily applied. Crosslinking polyvinyl acetates became preferable in some nonstructural, cold-set applications. Cheaper PF resins took over those exterior applications that allowed the use of heat and pressure. UF resins took over many interior applications on the basis of superior costs and mold resistance. Although the basic raw material cost is not a complete picture of the costs of its adhesive derivatives, it is a fairly good index. Table III shows how casein and blood compare with their competition at the present time. Although the exact prices of these materials fluctuate considerably, the approximate order of their costs has not changed much in the last 15 years. The materials are listed in order of cost. 

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