Anhydride component

Eor adhesive applications, it is more convenient to have the two components of the epoxy resin system react at a reasonable rate at room temperature. Replacing the anhydride component by a suitable, more reactive polyfunctional amine enables this to occur at room temperature. Several aliphatic and aromatic polyfunctional amines are used for this purpose (Eq. 21.28). 

The Initiation Mechanism with Phosphonium Compounds. Although further experimental data are needed to give a fuller understanding of the reaction mechanisms involved in the latent acceleration effect of these quaternary phosphonium compounds in epoxyanhydride resins, there is definite indication, at this stage, that the mechanism does not involve the decomposition of the phosphonium compound to the free phosphine species (16). The initiation mechanism probably involves the formation of hydrogen-bonded phosphonium-epoxy or phosphonium-anhydride complexes which rearrange on the application of heat to form activated species resulting in polymerization of the epoxy-anhydride components ( > ... 

The results given above indicate that, despite some variations in rate, anhydride end groups can all be classed as quite readily hydrolyzed. In contrast, the hydrolytic susceptibility of imide linkages varies much more with the polymer examined. BPDA-PDA showed no measurable imide hydrolysis whatsoever. In PMDA-ODA the amount of hydrolysis observed was small enough that we cannot eliminate the possibility that impurities in the anhydride component, rather than PMDA itself, resulted in the formation of hydrolyzable material. Of the polymers studied here, only those that contained BTDA as the anhydride component showed a marked susceptibility to imide hydrolysis. Even in this case, the data suggest that the reaction is limited in that only about 6-7% of the imide linkages appear to be susceptible to hydrolysis. 

Related condensations involving the replacement of the anhydride component with succinic acid (Fit-tig synthesis) or with malonic acid (Knoevenagel condensation, see Volume 2, Qiapter 1.11) provide complementary preparative methods which are useful for both aromatic and aliphatic systems. The Fittig extension of the Perkin transformation involves heating an aliphatic or aromatic aldehyde with sodium succinate and acetic anhydride to give the condensation products (17), which lose carbon dioxide to afford p,7-unsaturated cartoxylic acids (18), accompanied by small amounts of the corresponding 7-buty-rolactones (19 Scheme 7)P... 

FIGURE 5.25 o-Xylene and phthalic anhydride component effectiveness factors in multiplicity region. 

FIGURE 5.29 o-Xylene, phthalic anhydride and maleic anhydride component effectiveness factors. 

FIGURE 5.18 o-Xylene, o-tolualdchyde arid phthalic anhydride component effectiveness factors. 

Although acetic anhydride is often used in the Perkin reaction as the acid anhydride component, other acid anhydrides can be used in the Perkin reaction as well. Oglialoro reported that sodium phenylacetate 21 and acetic anhydride give a-phenylcinnamic acid 22. The Oglialoro modification generates a mixed anhydride in situ and is a convenient preparative method that obviates the necessity of using the arylacetic anhydride as a starting material.2... 

Resin Mixture of Maleic anhydrides anhydride Components [mol] Diethylene Propylene glycol glycol Glycerol Xylene... 

The mechanism of the reaction, which is of the aldol type, involves the car-bonyl group of tlie aldehyde and an active methylene group of the anhydride the function of the basic catalyst B (acetate ion 0H3000 or triethylamine N(0,Hb)j) is to form the anion of the active hydrogen component, i.e., by the extraction of a proton from the anhydride ... 

Division III. Heterocyclic compounds (Heterocyclic stem nuclei). The carbon atoms are joined in closed rings which include one or more other kinds of atoms as ring components. Anhydrides and imides of dibasic acids, as well as lactones, lactams, etc. are thus included in this division... 

Alkenylsuccinic anhydrides made from several linear alpha olefins are used in paper sizing, detergents, and other uses. Sulfosuccinic acid esters serve as surface active agents. Alkyd resins (qv) are used as surface coatings. Chlorendric anhydride [115-27-5] is used as a flame resistant component (see Flame retardants). Tetrahydrophthalic acid [88-98-2] and hexahydrophthalic anhydride [85-42-7] have specialty resin appHcations. Gas barrier films made by grafting maleic anhydride to polypropylene [25085-53-4] film are used in food packaging (qv). Poly(maleic anhydride) [24937-72-2] is used as a scale preventer and corrosion inhibitor (see Corrosion and corrosion control). Maleic anhydride forms copolymers with ethylene glycol methyl vinyl ethers which are partially esterified for biomedical and pharmaceutical uses (189) (see Pharmaceuticals). 

Aroma chemicals are isolates, or chemically treated oils or components of oils. Some components are removed physically, others chemically. In most cases, they are further purified by distillation. For example, Bois de Rose (rosewood) oil may be distilled to isolate linalool, which may be then further treated chemically to yield derivatives such as linalyl acetate, an important fragrance ingredient and a primary component in its own right of lavender and lavandin oils. Vetiver oil Haiti, although containing only 70% alcohols, is treated with acetic anhydride, then carefully distilled to include valuable odor components in the distillate, even though they may not be esters. 

The second largest use at 21% is for unsaturated polyester resins, which are the products of polycondensation reactions between molar equivalents of certain dicarboxyhc acids or thek anhydrides and glycols. One component, usually the diacid or anhydride, must be unsaturated. A vinyl monomer, usually styrene, is a diluent which later serves to fully cross-link the unsaturated portion of the polycondensate when a catalyst, usually a peroxide, is added. The diacids or anhydrides are usually phthahc anhydride, isophthahc acid, and maleic anhydride. Maleic anhydride provides the unsaturated bonds. The exact composition is adjusted to obtain the requked performance. Resins based on phthahc anhydride are used in boat hulls, tubs and spas, constmction, and synthetic marble surfaces. In most cases, the resins contain mineral or glass fibers that provide the requked stmctural strength. The market for the resins tends to be cychcal because products made from them sell far better in good economic times (see Polyesters,unsaturated). 

The properties of polymers formed by the step growth esterification (1) of glycols and dibasic acids can be manipulated widely by the choice of coreactant raw materials (Table 1) (2). The reactivity fundamental to the majority of commercial resins is derived from maleic anhydride [108-31-6] (MAN) as the unsaturated component in the polymer, and styrene as the coreactant monomer. Propylene glycol [57-55-6] (PG) is the principal glycol used in most compositions, and (i9f2v (9)-phthahc anhydride (PA) is the principal dibasic acid incorporated to moderate the reactivity and performance of the final resins. 

Dicylopentadiene Resins. Dicyclopentadiene (DCPD) can be used as a reactive component in polyester resins in two distinct reactions with maleic anhydride (7). The addition reaction of maleic anhydride in the presence of an equivalent of water produces a dicyclopentadiene acid maleate that can condense with ethylene or diethylene glycol to form low molecular weight, highly reactive resins. These resins, introduced commercially in 1980, have largely displaced OfXv o-phthahc resins in marine apphcations because of beneficial shrinkage properties that reduce surface profile. The inherent low viscosity of these polymers also allows for the use of high levels of fillers, such as alumina tfihydrate, to extend the resin-enhancing, fiame-retardant properties for apphcation in bathtub products (Table 4). 

Another sulfur dioxide appHcation in oil refining is as a selective extraction solvent in the Edeleanu process (323), wherein aromatic components are extracted from a kerosene stream by sulfur dioxide, leaving a purified stream of saturated aHphatic hydrocarbons which are relatively insoluble in sulfur dioxide. Sulfur dioxide acts as a cocatalyst or catalyst modifier in certain processes for oxidation of o-xylene or naphthalene to phthaHc anhydride (324,325). 

It is possible to react an organic moiety to the hydroxyl groups on ceU waU components. This type of treatment also bulks the ceU with a permanently bonded chemical (68). Many compounds modify wood chemically. The best results are obtained by the hydroxyl groups of wood reacting under neutral or mildly alkaline conditions below 120°C. The chemical system used should be simple and must be capable of swelling the wood stmcture to facUitate penetration. The complete molecule must react quickly with wood components to yield stable chemical bonds while the treated wood retains the desirable properties of untreated wood. Anhydrides, epoxides, and isocyanates have ASE values of 60—75% at chemical weight gains of 20—30%. 

Mixed Metal Oxides and Propylene Ammoxidation. The best catalysts for partial oxidation are metal oxides, usually mixed metal oxides. For example, phosphoms—vanadium oxides are used commercially for oxidation of / -butane to give maleic anhydride, and oxides of bismuth and molybdenum with other components are used commercially for oxidation of propylene to give acrolein or acrylonitrile. 

Even the earliest reports discuss the use of components such as polymer syrups bearing carboxylic acid functionality as a minor component to improve adhesion [21]. Later, methacrylic acid was specifically added to adhesive compositions to increase the rate of cure [22]. Maleic acid (or dibasic acids capable of cyclic tautomerism) have also been reported to increase both cure rate and bond strength [23]. Maleic acid has also been reported to improve adhesion to polymeric substrates such as Nylon and epoxies [24]. Adducts of 2-hydroxyethyl methacrylate and various anhydrides (such as phthalic) have also been reported as acid-bearing monomers [25]. Organic acids have a specific role in the cure of some blocked organoboranes, as will be discussed later. 

CH3COOH or A -h B —> 2C, where component A is the acetic anhydride. The rate expression is first order in terms of component A. 

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