Difunctional acid

Another potential lignin modification method concerns the reaction with difunctional acid chlorides, especially terephthaloyl chloride, to form cross-linked polymeric materials (1,10,14,20). Several studies have dealt with... 

The described procedure is useful for the preparation of a wide variety of compounds containing trifluoromethyl groups from the corresponding carboxylic acids.8 The yields are generally 60-90%. Some representative examples are listed in Table I. In the cases of the difunctional acids, only 0.1 mole of the compound should be used in the procedure. 

The name Nylon was given by the Du Pont company of America to their first synthetic condensation polymer formed by the reaction of difunctional acids with difunctional amines, ft had been made as part of the fundamental programme of W. H. Carothers to investigate the whole topic of polymerisation. The term has gradually been extended to other related polymers. These materials are strictly polyamides, but this term includes that otherwise distinct class of natural macromolecules, the proteins. The term nylon is retained for its usefulness in distinguishing synthetic polyamides from the broader class of such polymers. 

In a subsequent investigation by O Lenick [2] Guerbet acids were converted into the corresponding oligomers by reacting with difunctional acids while using benzene sulfonic acid as catalyst. Products were used to prepare lipstick. 

Equation (16) can lead to the formation of difunctional acids, lactones, methyl ketones with carbon chains shorter than the starting hydrocarbon, and other compounds [44, 45]. Back-biting reactions have the unique characteristic that it is not possible to dilute the site of a back-biting attack with respect to the attacking radical. In the normal chain propagation (eq. (2)), such dilution with respect to the attacking radical can be achieved by, for example, holding the conversion at a lower level. 

The difunctional acid anions have only been recognized to exist in very high concentrations in a few instances. Propanedioic (malonic) and Z-butenedioic (maleic) acid anions and the C4 to Cio difunctional CAA have been reported in formation waters (1.32) however, reported concentrations were low. Barth (44) reported the concentration of ethanedioic (oxalic) and propanedioic (malonic) acid anions in formation waters in concentrations up to 38 and 102 ppm respectively. MacGowan and Surdam (25) report concentrations of difunctional CAA in excess of 2500 ppm in California formation waters, although most concentrations of total difunctional CAA are well below 200... 

Friedel-Crafts reaction of the difunctional acid chloride of 361 gave exclusively monocyclization to 362 (70%). Compound 363 (obtained as a 1.8 1 mixture of cis-trans isomers, 67%) gave a mixture of 364 (54%) and 25 (20%) from reduction plus dehydration. Dehydrogenation of this mixture produced 25 only (50%). Lamberton and Paine129 used the acid chloride method to convert acid 364a to phenol 364b (42%, m.p. 250°C methyl ether, m.p. 163°C). 

The basic reaction of alkyds is esterification. A difunctional acid such as phthalic anhydride, a monofunctional fatty acid such as soya fatty acid, and a polyfunctional alcohol such as glycerine or pentaerythitol are reacted together under conditions of heat, catalyst, and elimination of water. Conventional esterification catalysts are effective. 

As sodium acetate is titrated, the acetate ion is replaced by the chloride ion, which, owing to its slightly higher ionic-equivalent conductance, causes a slight increase in conductivity up to the endpoint. Beyond the endpoint, excess hydrochloric acid causes large increases. Such titrations are useful where the ionization constant of the liberated weak acid or base, when divided by the salt s concentration, does not exceed 5 x 10" . If a difunctional acid is formed, then the two ionization constants should differ by about 1Q- if two endpoints are to be observed NajS is an example of this type. Figure 5.9 shows typical replacement titration curves. 

Chlorendic anhydride (1,4,5,6,7,7-hexa-chloro-5-norbornene-2,3-dicar-boxylic anhydride, HET anhydride, a difunctional acid anhydride) n. HET anhydride is a white, crystalline powder used as a hardening agent and flame retardant in epoxy, alkyd, and polyester resins (See image). 

It appears that carboxyl-modification is necessary for bonding polymer latexes through amine-functional silanes. A series of experimental styrene-butadiene-acid terpolymers were compared as film formers and primers with 5% added Z-6020 (Table V). Difunctional acids gave the most stable mixes, but poorest water resistance. Polymers with acrylic acid modification were best primers for plaster. Alkylmaleate modified polymers had poor stability with silane, and deposited rubbery films with poor wet adhesion to glass. 

Substituting formic, propionic, or butyric acid for acetic acid in the esterification reaction yields the corresponding formate, propionate, and butyrate esters. Lactic acid and oxalic acid (a difunctional acid) can also be reacted with alcohols to give the lactate and oxalate ester solvents. A versatile series of esters formed from the reaction of methanol with difunctional adipic, glutaric, and succinic acids yield the dibasic esters which are commonly referred to as DBE solvents. Reaction of lower aliphatic alcohols with t)-phthalic acid or phosphoric acid yield the corresponding phthalate and phosphate esters. Another important group of esters are obtained from the... 

Phthalic anhydride is the difunctional acidic component most widely used for the preparation of alkyd resins. Manufacture of the material is dealt with in Section 10.2.2.3. Phthalic anhydride is preferred in this application on account of its low cost and because it gives rise to resins with good solubility and compatibility characteristics and good film properties. Other dibasic acids and anhydrides, which are used to a lesser extent, include maleic anhydride (Section 10.2.2.2), isopthalic acid (VI), adipic acid and sebacic add (Section 9.2.2). 

Condensation of a difunctional amine with a difunctional acid ... 

In practice, difunctional acids and diphenols are little used as curing agents for epoxy resins. They are, however, often used in combination with a second, more highly functional or efficient curing agent (novolac resins or fatty trimer acids). 

Esterification of carboxylic acids followed by hydrocarbon extraction and gas chromatography has been widely used (e.g., Willey et al. 1975 Carothers and Kharaka 1978 Kharaka et al. 1985). The main advantage of this method is the ability to detect and quantify some of the longer-chain acids that are not detectable by other methods. The disadvantages are that (1) many of the esters of these carboxylic acids are more hydrophilic than hydrophobic, and thus are never extracted into the analate and (2) the short-chain difunctional acid esters are apt to either precipitate as insoluble Ca or Mg salts during evaporative concentration of the extract, or totally decarboxylate at the injection port, and thus are either not analyzed or are analyzed as CO2, respectively (Kawamura et al. 1986 Alltech Associates 1985). This method is also expensive and time-consuming. 

Fig. 2. Schematic chromatogram showing relative peak heights and elution times for monofunctional, hydroxybenzoic, and difunctional acids...

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