Resorcinol additives

Resorcinol chemistry can aid in developing high barrier polymeric materials, according to Indspec Chemical Corp. Three relevant derivatives are resorcinol dioxyacetic acid (RDOA), bis-(hydroxyethyl)-ether of resorcinol (HER) and resorcinol diglycidyl ether (RDGE). 

Six major breweries have successfully bottled beer in plastic containers Miller, Heineken, Bass, Feldschlossen. Carlton United, and Carlsberg. The bottle for Miller Lite was developed by Continental PET Technologies, using five layers, with a PA (nylon MXD6) barrier layer less than 5 wt% of the container. In Australia, Carlton United introduced a monolayer bottle coated with PPG Industries Bairocade coating. 

Since the main component of these bottles is PET with a relatively low barrier, the expected shelf life is around three months but, with the development of improved oxygen permeability (P02) and carbon dioxide (PCO2). of the barrier materials, it should be possible to deliver bottles with a shelf life of 6-9 months. The industry is aiming at polymer combinations offering values of P02 0.5 BU and PCO2 2-3 BU. 

P02 values and tensile strength of polyamides and polyesteramides incorporating RDOA monomer suggest that there is a tremendous opportunity for development of high barrier packaging materials, considers Indspec. The lowest P02 values indicate that monolayer containers with high gas barrier properties can be made and used for preserving the taste of beer over an extended period of time, without further modifications. 

MXD6 is a polyamide made from the reaction of MXDA and adipic acid, giving a P02 value of 0.6 BU. But a polyamide made from MXDA and RDOA shows a 

---

Up 1.4575. Purified by dilution with an equal volume of pet ether, then saturated with dry HBr. The ppte was filtered off, washed with small vols of pet ether, then cineole was regenerated by stirring the crystals with H2O. It can also be purified via its o-cresol or resorcinol addition compds. Stored over Na until required. Purified by fractional distn. Insoluble in H2O but soluble in organic solvents. [IR Kome et al. Nippon Kagaku Zasshi [J Chem Soc Japan (Pure Chem Sect)] 80 66 1959 Chem Abstr 603 1961.]... 

Resorcinol will react rapidly with hydroxymethyl as well as free formaldehyde thus only a resin with low-to-nonexistent methylol will be stable in its presence. Such a resin is not likely to show good cure speed unless some sort of latent, protected methylene donor is present. This approach may be viable in a user s mill where the storage time after resorcinol addition is relatively short. If the resorcinol is dissolved, in-line mixing with the PF would be a reasonable approach. 

Resorcinol additions just prior to use provide acceleration, though they are still not the most cost effective nor technically effective use of resorcinol. In-line addition of a PRF resin Just before application of the resin to the adherend achieves better results at less than half the cost of resorcinol chemical, in most cases and it is easier to handle. A variant of this concept is application of the resorcinol and PF resins to the substrate separately but in a way that permits them to come into contact during the curing process. Such methods are sometimes called honeymoon systems. 

The mechanism of step la is questionable in acidic solutions, because of the very low amount of charged species (resorcinol anions) present at the beginning of the polymerization reaction. In this case, the charged species that activates the addition reaction is probably the protonated form of formaldehyde, (CHj-OH) (step lb), which is more sensitive to resorcinol addition than molecular formaldehyde. 

Fluorescein is obtained by condensing phthahc anhydride (1 mol) with resorcinol (2 mols) in the presence of anhydrous zinc chloride. The tetra-bromo derivative, readily prepared by the addition of the calculated quantity of bromine, is eosin. 

Both melamine—formaldehyde (MF) and resorcinol—formaldehyde (RF) foUowed the eadier developments of phenol—, and urea—formaldehyde. Melamine has a more complex stmcture than urea and is also more expensive. Melamine-base resins requite heat to cure, produce colorless gluelines, and are much more water-resistant than urea resins but stiU are not quite waterproof. Because of melamine s similarity to urea, it is often used in fairly small amounts with urea to produce melamine—urea—formaldehyde (MUF) resins. Thus, the improved characteristics of melamine can be combined with the economy of urea to provide an improved adhesive at a moderate increase in cost. The improvement is roughly proportional to the amount of melamine used the range of addition may be from 5 to 35%, with 5—10% most common. 

Medicated Dandruff Shampoos. Dandmff is a scalp condition characterized by the production of excessive cellular material (18). A number of shampoos have been marketed which are designed to control and alleviate this condition, and many additives have been included in shampoo compositions to classify them as treatment products for dandmff. These additives include antimicrobial additives, eg, quaternary ammonium salts keratolytic agents, eg, saUcychc acid and sulfur heavy metals, eg, cadmium sulfide coal tar resorcinol and many others. More recent (ca 1993) systems use selenium sulfide [7488-56-4] or zinc pyrithione [13463-41 -7] as active antidandmff shampoo additives. Both of these additives are classified as dmgs, but can be found in over-the-counter products. A stronger version, incorporating the use of higher levels of selenium sulfide in a shampoo, is available but requires a prescription for purchase. 

After sulfuric acid work-up (accompanied by the formation of sodium sulfate), the resorcinol is extracted and isolated in a 94% yield based on y -benzenedisulfonic acid [98-48-6]. In addition to the technical complexity that goes along with the manipulation of soHds at high temperature, this process produces large amounts of salts (sulfite and sulfate salts) which economically as well as environmentally are not always desired. 

Resorcinol or hydroquinone production from m- or -diisopropylben2ene [100-18-5] is realized in two steps, air oxidation and cleavage, as shown above. Air oxidation to obtain the dihydroperoxide (DHP) coproduces the corresponding hydroxyhydroperoxide (HHP) and dicarbinol (DC). This formation of alcohols is inherent to the autooxidation process itself and the amounts increase as DIPB conversion increases. Generally, this oxidation is carried out at 90—100°C in aqueous sodium hydroxide with eventually, in addition, organic bases (pyridine, imidazole, citrate, or oxalate) (8) as well as cobalt or copper salts (9). 

Methylene chloride is one of the more stable of the chlorinated hydrocarbon solvents. Its initial thermal degradation temperature is 120°C in dry air (1). This temperature decreases as the moisture content increases. The reaction produces mainly HCl with trace amounts of phosgene. Decomposition under these conditions can be inhibited by the addition of small quantities (0.0001—1.0%) of phenoHc compounds, eg, phenol, hydroquinone, -cresol, resorcinol, thymol, and 1-naphthol (2). Stabilization may also be effected by the addition of small amounts of amines (3) or a mixture of nitromethane and 1,4-dioxane. The latter diminishes attack on aluminum and inhibits kon-catalyzed reactions of methylene chloride (4). The addition of small amounts of epoxides can also inhibit aluminum reactions catalyzed by iron (5). On prolonged contact with water, methylene chloride hydrolyzes very slowly, forming HCl as the primary product. On prolonged heating with water in a sealed vessel at 140—170°C, methylene chloride yields formaldehyde and hydrochloric acid as shown by the following equation (6). 

In the known absence of bromoform, iodoform, chloral, and other halogenated methanes, the formation of phenyhsonitrile with aniline provides a simple and faidy sensitive but nonspecific test for the presence of chloroform, the carbylamine test. Phenyhsonitrile formation is the identification test given in the British Pharmacopoeia. A small quantity of resorcinol and caustic soda solution (10% concentration) added to chloroform results in the appearance of a yellowish red color, fluorescing yeUow-green. When 0.5 mL of a 5% thymol solution is boiled with a drop of chloroform and a small quantity of potassium hydroxide solution, a yellow color with a reddish sheen develops the addition of sulfuric acid causes a change to brilliant violet, which, diluted with water, finally changes to blue (33). 

Further improvement in light stability may be achieved by addition of small quantities of ultraviolet absorbers. Typical examples include phenyl salicylate, 2,4-dihydroxybenzophenone, resorcinol monobenzoate, methyl salicylate and stilbene. 

Adolph Baeyer is credited with the first recognition of the general nature of the reaction between phenols and aldehydes in 1872 ([2,5-7] [18], Table 5.1). He reported formation of colorless resins when acidic solutions of pyrogallic acid or resorcinol were mixed with oil of bitter almonds, which consists primarily benzaldehyde. Baeyer also saw resin formation with acidic and basic solutions of phenol and acetaldehyde or chloral. Michael and Comey furthered Baeyer s work with additional studies on the behavior of benzaldehyde and phenols [2,19]. They studied a variety of acidic and basic catalysts and noted that reaction vigor followed the acid or base strength of the catalyst. Michael et al. also reported rapid oxidation and darkening of phenolic resins when catalyzed by alkaline materials. 

Recently, a two-part cross-catalyzed system has been developed that takes advantage of both the acceleration abilities of resorcinol resin and ester [179], The term cross-catalyzed is applied because the phenolic resin contains an accelerator-crosslinker for the resorcinol resin while the resorcinol resin carries an accelerator for the PF, in addition to itself being capable of improving PF cure speed. In each part, the resin carrier for the accelerator is not susceptible to acceleration by the material contained. It is only when the systems are mixed that the accelerators are activated. This system is faster and lower in cost than most of the resorcinol accelerators and gives better bonds (in wood products) than the ester cure alone [179], Another variant of the resorcinol approach utilizes resorcinol-glutaraldehyde resins [180-182],... 

While phenol is the most common monomer for novolac manufacture, it is far more common to see incorporation of other phenolic materials with novolacs than with resoles. Cresols, xylenols, resorcinol, catechols, bisphenols, and a variety of phenols with longer alkyl side chains are often used. While most resoles are made with a single phenolic monomer, two or more phenolic materials are often seen in novolac formulae. These additional monomers may be needed to impart special flow characteristics under heat, change a glass transition temperature, modify cure speed, or to adjust solubility in the application process among others. 

In the manufacture of pure resorcinol resins, the reaction can be violently exothermic unless controlled by the addition of alcohols. Because the alcohols perform other useful functions in the glue mix, they are left in the liquid adhesive. PRF adhesives are generally prepared firstly by reaction of phenol with formaldehyde to form a PF resol polymer, that has been proved to be in the greatest percentage, and often completely, linear [95], In the reaction step that follows the resorcinol chemical is added in excess to the PF-resol to react it with the PF-resin -CH2OH groups to form PRF polymers in which the resorcinol groups can be resorcinol chemical or any type of resorcinol-formaldehyde polymer. 

Polyethylene separators offer the best balanced property spectrum excellent mechanical and chemical stability as well as good values for acid availability and electrical resistance have established their breakthrough to be the leading traction battery separator. Rubber separators, phenolic resin-resorcinol separators, and mi-croporous PVC separators are more difficult to handle than polyethylene separators their lack of flexibility does not allow folding into sleeves or use in a meandering assembly in addition they are more expensive. 

An additional activating hydroxyl group on the phenolic ring allows resorcinol to react rapidly widi formaldehyde even in die absence of catalysts.8 Hiis provides a method for room temperature cure of resorcinol-formaldehyde resins or mixed phenol-formaldehyde/resorcinol-formaldehyde resins. Trihydric phenols have not achieved commercial importance, probably due to tiieir higher costs. 

---