Rosin structures

Further, the hydrocarbon nature of rosin structures imparts an excellent hydrophobicity to the PCL with a contact angle closely to that of poly(styrene) thus effecting a very low water absorption. The graft copolymers maintain the full degradability and a good biocompatibiUty. 

Src tyrosine kinase contains both an SH2 and an SH3 domain linked to a tyrosine kinase unit with a structure similar to other protein kinases. The phosphorylated form of the kinase is inactivated by binding of a phosphoty-rosine in the C-terminal tail to its own SH2 domain. In addition the linker region between the SH2 domain and the kinase is bound in a polyproline II conformation to the SH3 domain. These interactions lock regions of the active site into a nonproductive conformation. Dephosphorylation or mutation of the C-terminal tyrosine abolishes this autoinactivation. 

Rosin and tall oil-based tackifiers are derived from feedstock, which is typically obtained by extraction and distillation of the materials from shredded tree stumps or wood chips. A typical structure of one of the different products obtained through this process is this abietic acid structure shown in Fig. 14 as a representative of the rosin acid family. 

In this section the rosins and rosin derivative resins, coumarone-indene and hydrocarbon resins, polyterpene resins and phenolic resins will be considered. The manufacture and structural characteristics of natural and synthetic resins will be first considered. In a second part of this section, the characterization and main properties of the resins will be described. Finally, the tackifier function of resins in rubbers will be considered. 

Most of the inhibitors in use are organic nitrogen compounds and these have been classified by Bregman as (a) aliphatic fatty acid derivatives, b) imidazolines, (c) quaternaries, (d) rosin derivatives (complex amine mixtures based on abietic acid) all of these will tend to have long-chain hydrocarbons, e.g. CigH, as part of the structure, (e) petroleum sulphonic acid salts of long-chain diamines (preferred to the diamines), (/) other salts of diamines and (g) fatty amides of aliphatic diamines. Actual compounds in use in classes (a) to d) include oleic and naphthenic acid salts of n-tallowpropylenediamine diamines RNH(CH2) NH2 in which R is a carbon chain of 8-22 atoms and x = 2-10 and reaction products of diamines with acids from the partial oxidation of liquid hydrocarbons. Attention has also been drawn to polyethoxylated compounds in which the water solubility can be controlled by the amount of ethylene oxide added to the molecule. 

Rosin is an organic flux that has long been used for soldering. It is a yellow, transparent, and relatively hard resin secreted from wounds in the trunks of coniferous trees. Rosin is insoluble in water, and its exact composition and structure are as yet unknown. 

Terpenoids are susceptible to a number of alterations mediated by oxidation and reduction reactions. For example, the most abundant molecule in aged Pinus samples is dehydroabietic acid [Structure 7.10], a monoaromatic diterpenoid based on the abietane skeleton which occurs in fresh (bleed) resins only as a minor component. This molecule forms during the oxidative dehydrogenation of abietic acid, which predominates in rosins. Further atmospheric oxidation (autoxidation) leads to 7-oxodehydroabietic acid [Structure 7.11]. This molecule has been identified in many aged coniferous resins such as those used to line transport vessels in the Roman period (Heron and Pollard, 1988 Beck et al., 1989), in thinly spread resins used in paint media (Mills and White, 1994 172-174) and as a component of resin recovered from Egyptian mummy wrappings (Proefke and Rinehart, 1992). 

Figure 2.9 The molecular structure of abietic acid—the dominant component of wood rosin.

Studies of the metal-exchange process of P.R.49 (Na) to P.R.49 1 (Ba) [1] revealed that the process, apart from the temperature, is not only influenced by the crystal structure and the concentration of the barium ions but also by the amount of rosin soap. Colophony-based rosin which is assumed to act as a surfactant, is converted during the laking process into colorless insoluble rosinate salts. These salts are incorporated in the pigment til up to 30% by weight without a loss of tinctorial strength. Very often the color strength is even increased, accompanied by a color shift to more bluish reds. 

Rosin is compatible with many materials because of its polar functionality, cycloaliphatic structure, and its low molecular weight. It has an acid number of ca 165 and a saponification number of ca 170. It is soluble in aliphatic, aromatic, and chlorinated hydrocarbons, as well as esters and ethers. Because of its solubility and compatibility characteristics, it is useful for modifying the properties of many polymers. 

Composition. Rosin is primarily a complex mixture of monocarboxylic acids of alkylated hydrophenanthrene nuclei. These constituents, known as resin acids, represent about 90% of rosin. The resin acids are subdivided into two types, based on their skeletal structure. The abietic-type acids contain an isopropyl group pendent from the carbon numbered 13. The pimaric-type acids have a methyl and vinyl group pendent from the same carbon atom. Figure 1 shows the structure of typical resin acids abietic acid, C20H30O2 (1) is predominant. The remaining 10% of commercial rosin consists of neutral materials that are either hydrocarbons or saponifiable esters. These materials are derived from resin acids by decarboxylation or esterification. 

Dimerization is mediated by the phosphotyrosine residue and the SH2 domain. Highly resolved structural investigation show that the phosphotyrosine residue of one Stat protein binds to the SH2 domain of the partner and vice versa, so that the phosphoty-rosine-SH2 bonds fimction as a double clasp (structure in complex with DNA Becker et al., 1998 Chen et al., 1998). The binding to DNA is in the form of a dimer, with the Stat-DNA complex showing a large similarity to the structure of the NFxB-DNA complex (see Fig. 1.10). 

Ethoxylation of alkyl amine ethoxylates is an economical route to obtain the variety of properties required by numerous and sometimes small-volume industrial uses of cationic surfactants. Commercial amine ethoxylates shown in Tables 27 and 28 are derived from linear alkyl amines, aliphatic /-alkyl amines, and rosin (dehydroabietyl) amines. Despite the variety of chemical structures, the amine ethoxylates tend to have similar properties. In general, they are yellow or amber liquids or yellowish low melting solids. Specific gravity at room temperature ranges from 0.9 to 1.15, and they are soluble in acidic media. Higher ethoxylation promotes solubility in neutral and alkaline media. The lower ethoxylates form insoluble salts with fatty acids and other anionic surfactants. Salts of higher ethoxylates are soluble, however. Oil solubility decreases with increasing ethylene oxide content but many ethoxylates with a fairly even hydrophilic—hydrophobic balance show appreciable oil solubility and are used as solutes in the oil phase. 

The chemical structures of thyroxine and triiodothyronine are shown in Figure 31—1. As shown in the figure, thyroid hormones are synthesized first by adding iodine to residues of the amino acid tyrosine. Addition of one iodine atom creates monoiodotyrosine, and the addition of a second iodine creates diiodotyrosine. Two of these iodinated tyrosines are then combined to complete the thyroid hormone. The combination of a monoiodotyrosine and a diiodotyrosine yields triiodothyronine, and the combination of two diiodoty-rosines yields thyroxine.55... 

The alternative stereochemistry typified by labdadienyl PP can be seen in the structure of abi-etic acid (Figure 5.48), the major component of the rosin fraction of turpentine from pines and other conifers (Table 5.1). Initially, the tricyclic system is built up as in the pathway to /-kaurene (Figure 5.47), via the same mechanism, but generating the enantiomeric series of compounds. The cation loses a proton to give sandaracopimara-diene (Figure 5.48), which undergoes a methyl... 

Rosin contains -COOH and double bonds in its molecular structure. Rosin contains mainly cyclic compounds as follows. 

Rosinate and Cholate. These carboxylates were included because of their different (from fatty acid) structure rosin acids compose about half of the tall oil acids and cholic acid is a representative bile acid that is important in the animal metabolism of fats. Salts of these acids had interfacial tensions that were significantly higher than oleate no minima were found (Figure 7)-... 

All rosins are made up of 90-95% of diterpenic monocarboxylic acids, or resin acids , Q9H29COOH, in different specific molecular architectures. Their most common structures can be subdivided into those bearing two conjugated double... 

The aspects relevant to the use of rosin as such, or one of the derivatives arising from its appropriate chemical modification as monomer or comonomer [12-14], have to do with the synthesis of a variety of materials based on polycondensations and polyaddition reactions of structures bearing such moieties as primary amines, maleimides, epoxies, alkenyls and, of course, carboxylic acids. These polymers find applications in paper sizing, adhesion and tack, emulsification, coatings, drug delivery and printing inks. 

---