Trimer acid

This type of cement has been further improved by the substitution of -hexyl van ill ate [84375-71-3] and similar esters of vanillic acid [121 -34-6] and/or syringic acid [530-57 ] for eugenol (93—95). These substituted cements are strong, resistant to dissolution, and, unlike ZOE and EBA cements, do not inhibit the polymerization of resin-base materials. Noneugenol cements based on the acid—base reaction of zinc and similar oxides with carboxyhc acids have been investigated, and several promising types have been developed based on dimer and trimer acids (82). 

Calcium Chelates (Salicylates). Several successhil dental cements which use the formation of a calcium chelate system (96) were developed based on the reaction of calcium hydroxide [1305-62-0] and various phenohc esters of sahcyhc acid [69-72-7]. The calcium sahcylate [824-35-1] system offers certain advantages over the more widely used zinc oxide—eugenol system. These products are completely bland, antibacterial (97), facihtate the formation of reparative dentin, and do not retard the free-radical polymerization reaction of acryhc monomer systems. The principal deficiencies of this type of cement are its relatively high solubihty, relatively low strength, and low modulus. Less soluble and higher strength calcium-based cements based on dimer and trimer acid have been reported (82). 

The clay-cataly2ed iatermolecular condensation of oleic and/or linoleic acid mixtures on a commercial scale produces approximately a 60 40 mixture of dimer acids and higher polycarboxyUc acids) and monomer acids (C g isomerized fatty acids). The polycarboxyUc acid and monomer fractions are usually separated by wiped-film evaporation. The monomer fraction, after hydrogenation, can be fed to a solvent separative process that produces commercial isostearic acid, a complex mixture of saturated fatty acids that is Hquid at 10°C. Dimer acids can be further separated, also by wiped-film evaporation, iato distilled dimer acids and trimer acids. A review of dimerization gives a comprehensive discussion of the subject (10). 

Siace dimer acids, monomer acids, and trimer acids are unsaturated, they are susceptible to oxidative and thermal attack, and under certain conditions they are slightly corrosive to metals. Special precautions are necessary, therefore, to prevent product color development and equipment deterioration. Type 304 stainless steel is recommended for storage tanks for dimer acids. Eor heating coils and for agitators 316 stainless steel is preferred (heating coils with about 4s m (50 ft ) of heat transfer surface ia the form of a 5.1 cm schedule-10 U-bend scroU are recommended for a 37. 9-m (10,000-gal) tank. Dimer acid storage tanks should have an iaert gas blanket. 

Currently, there is continuing work on an iadustry standard method for the direct determination of monomer, dimer, and trimer acids. Urea adduction (of the methyl esters) has been suggested as a means of determining monomer ia distilled dimer (74). The method is tedious and the nonadductiag branched-chain monomer is recovered with the polymeric fraction. A micro sublimation procedure was developed as an improvement on urea adduction for estimation of the polymer fraction. Incomplete removal of monomer esters or loss of dimer duriag distillation can lead to error (75). 

The acute oral toxicity and the primary skin and acute eye irritative potentials of dimer acids, distilled dimer acids, trimer acids, and monomer acids have been evaluated based on the techniques specified ia the Code of Eederal Regulatioas (CER) (81). The results of this evaluatioa are showa ia Table 7. Based oa these results, monomer acids, distilled dimer acids, dimer acids, and trimer acids are classified as nontoxic by ingestion, are not primary skin irritants or corrosive materials, and are not eye irritants as these terms are defined ia the Eederal regulatioas. 

Flammability. Dimer and trimer acids, as well as monomer acids derived from dimer acid processing, are neither flammable nor combustible as defined by the Department of Transportation (DOT) and do not represent a fire ha2ard ... 

Cowan Teeter (1944) reported a new class of resinous substances based on the zinc salts of dimerized unsaturated fatty acids such as linoleic and oleic acid. The latter is referred to as dimer acid. Later, Pellico (1974) described a dental composition based on the reaction between zinc oxide and either dimer or trimer acid. In an attempt to formulate calcium hydroxide cements which would be hydrolytically stable, Wilson et al. (1981) examined cement formation between calciimi hydroxide and dimer acid. They found it necessary to incorporate an accelerator, alimiiniiun acetate hydrate, Al2(OH)2(CHgCOO)4.3H2O, into the cement powder. 

Since dimer acids, monomer acids, and trimer acids are unsaturated, they are susceptible to oxidative and thermal attack, and under certain conditions they are slightly corrosive to metals, Special precautions arc necessary, therefore, to prevent product color development and equipment deterioration. 

Alkali dithioformates can be prepared according to reaction (10) in a methanolic medium. The unstable free monomeric add, which trimerizes within a few minutes, is formed when an aqueous solution of these compounds is treated with HC1. The trimeric acid turns into the polymeric product (24) in DMF or DMSO. The alkali metal compounds are light and oxygen sensitive. Its complexes with Cu", Tl1, In1" and PbD are stable, whereas the Ag1, FeD, Co" and Ni compounds decompose and give the metal sulfides.1... 

Aitzetmuller (69,70) indicated that SEC can be used as a measure and indication of the extent of heating and polymerization of heated fats and oil. Harris et al. (71) achieved SEC separation of monomer, dimer, and trimer acids within 3 h, and quantitation was possible with the use of heptanoic acid as internal standard. 

Acids Phosphoric acid, FFAP (carbowax-20m-terephthalic acid ester), trimer acid These modifiers will act as subtractive agents for basic components in the sample FFAP will selectively abstract aldehydes phosphoric acid may convert amides to the nitrile (of the same carbon number), desulfonate sulfur compounds, and may esterify or dehydrate alcohols... 

FIGURE 8.16 Monomers used for trimeric acid-like molecules. 

ANEDCO AC-163 is a versatile basic intermediate which can be further modified by reacting with dimer-trimer acids to obtain an excellent film persistent-corrosion inhibitor. Various surfactants may be added to obtain improved water dispersibility. ANEDCO AC-163 may be reacted with a short chain organic acid such as acetic acid, hydroxy acetic acid, etc. to form a water-soluble corrosion inhibitor. 

The synthesis of dimeric fatty acids is based on the reaction between a fatty acid with one double bond (oleic acid) and a fatty acid with two double bonds (linoleic acid) or three double bonds (linolenic acid), at higher temperatures in the presence of solid acidic catalysts (for example montmorillonite acidic treated clays). Dimerised fatty acids (C36) and trimerised fatty acids (C54) are formed. The dimer acid is separated from the trimeric acid by high vacuum distillation. By using fatty dimeric acids and dimeric alcohols in the synthesis of polyesters and of polyester polyurethanes, products are obtained with an exceptional resistance to hydrolysis, noncrystalline polymers with a very flexible structure and an excellent resistance to heat and oxygen (Chapter 12.5). Utilisation of hydrophobic dicarboxylic acids, such as sebacic acid and azelaic acid in polyesterification reactions leads to hydrolysis resistant polyurethanes. 

An important development in the area of polyols from renewable resources was realised by transformation of the dimeric or trimeric acids (or of corresponding methyl esters) by hydrogenation in C36 diols or C54 triols. 

By hydrogenation of these dimeric or trimeric acids the corresponding diols or triols are obtained. The dimer alcohol (Figure 17.12) has an hydroxyl number of 202-212 mg KOH/g and a molecular weight of 565 daltons and a viscosity of around 3,500 mPa-s at 25 °C [73, 74]. Trimer alcohols (Figure 17.13) have an hydroxyl number about 205 mg KOH/g and a viscosity of around 9,500 mPa-s at 25 °C [74]. 

A head to tail arrangement was observed for the intermolecular reaction of activated o-aminobenzoic acid. The final cyclization step used DCC activation on the cu-amino trimeric acid, which first had to be prepared (Edge et al., 1981, 1982 Hoorfar et al., 1982a Ollis et al., 1975). Thionyl chloride... 

Dimer acid, trimer acid, and small amounts of higher polymers are formed when tall oil fatty acid is treated with an active clay (37). In the same process, part of the fatty acid is isomerized to methyl-branched acids. These can be hydrogenated to produce a mixture of isostearic and stearic acids, which can be separated by a solvent crystallization process. Dimer acids are separated from trimers by thin-film or molecular distillation. 

Pripol. [Unichema Unichema France SA] IMmer or trimer acids modifier for nylon, polyester fibers used in polyamide for hot melt adhesives, thermographic inks, urrfhane elastomers, industrial lubricants, fuel additives, surface coadng resins, spin finishes. 

PripoL [Unidiema Unichema Fnmce SA] Dimer ro trimer acids modifier fro nylon, polyester fibros used in polyamide for hot melt adhesives, ther-mogrs diic inks, urethane elastomers, industrial lubriemts, fuel additives, surface coatiiig reshfi, qun finishes. 

Soybean oil may be hydrolyzed into glycerol and fatty acids, or soybean oil soap-stocks (foots) may be acidified to produce fatty acids. Crude soybean fatty acids are used to make adhesive tape, shaving compounds, textile water repellents, carbon paper, and typewriter ribbons. Consumption of fatty acids in the United States, Western Europe, and Japan was 2.3 MMT (2.5 million t) in 2001. These soybean fatty acids can be separated into various fractions by distillation, and are used in candles, crayons, cosmetics, polishes, buffing compounds, and mold lubricants. These fatty acids can be converted to FAME by esterification, alkyl epoxy esters by epoxidation, fatty alcohols by hydrogenation (Kreutzer, 1983 Voeste Buchold, 1983), and dimer and trimer acids by conjugation or amines and amides as shown in Fig. 17.7 (Maag, 1983). 

Antonucci, J.M. S. Venz D.J. Dudderar M.C. Pham J.W. Stansbury. Energy-absorbing, hydro-phobic dental cements based on dimer and trimer acids. Transactions of the Annual Meeting of the Society for Biomaterials in Conjunction with the International Biomaterials Symposium. 1984, pp. 137. 

A trigonal symmetry of host molecules provides a typical template for obtaining cavities or channels. In the crystal structure of a-TMA (TMA = trimeric acid, the parent acid of the BTC anion), mutual triple catenation of hydrogen-bonded TMA was found. However, selfpenetration is preventable, if the TMA was crystallized with template molecules or is functionalized with bulky substituents to obtain a rigid arrangement. 

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