Ester mixed esters

Since this early work, a very large range of organic acids has been used to prepare cellulose esters, mixed esters, and ethw esters (Rouse, 1965). A typical example of considerable commercial importance is the acetylation of cellulose. As in aU esterifications of macromolecular materials, the accessibility of the hydroxyl groups to the esterilying acid is of prime importance. Reaction (11.1) represents complete esterification, a process that is probably never fuUy achieved. The identification of the esterified products is, therefore, dependent not only on the content of acetyl groups but also on the location of these groups on the macromolecular backbone. Both factors are affected by the method of preparation and the esterification conditions. 

Butanedioic acid, 3-(2,3-dihydroxypropoxy)-2-hydroxypropyi ester, mixed esters with octanoic acid and decanoic acid. See Caprylic/capric digiyceryl succinate Butanedioic acid, ((dimethoxyphosphinyi) thio)-, diethyl ester. See Malaoxon Butanedioic acid, dimethyl ester. See Dimethyl succinate... 

The separation of these compounds which are often very similar, frequently unstable and may interconvert on thin layer chromatography, is sometimes very difficult. High pressure liquid chromatography has been much used, but is not free from problems of isomerisation. Separation is further complicated by the occurrence of mixtures of esters mixed esters of isobutyric and 2-methylbutyric acids are particularly common and difficult to separate. 

Synonyms Butanedioic acid, 3-(2,3-dihydroxypropoxy)-2-hydroxypropyl ester, mixed esters with octanoic acid and decanolc acid Classification Semisynthetic compound... 

Inspired by the many hydrolytically-active metallo enzymes encountered in nature, extensive studies have been performed on so-called metallo micelles. These investigations usually focus on mixed micelles of a common surfactant together with a special chelating surfactant that exhibits a high affinity for transition-metal ions. These aggregates can have remarkable catalytic effects on the hydrolysis of activated carboxylic acid esters, phosphate esters and amides. In these reactions the exact role of the metal ion is not clear and may vary from one system to another. However, there are strong indications that the major function of the metal ion is the coordination of hydroxide anion in the Stem region of the micelle where it is in the proximity of the micelle-bound substrate. The first report of catalysis of a hydrolysis reaction by me tall omi cell es stems from 1978. In the years that... 

Another ester synthesis employs the reaction of a long-chain ketone and pentaerythritol in xylene or chlorobenzene (14). Mixed esters have been produced using mixed isostearic and cyclohexane carboxyUc acids in trihromophosphoric acid, followed by reaction with lauric acid (15). 

Cotton linters or wood pulp are nitrated using mixed acid followed by treatment with hot acidified water, pulping, neutralization, and washing. The finished product is blended for uniformity to a required nitrogen content. The controlling factors in the nitration process are the rates of diffusion of the acid into the fibers and of water out of the fibers, the composition of mixed acid, and the temperature (see Cellulose esters, inorganic esters). 

Various other diesters, mixed esters, and polyesters of trimethylpentanediol are useful as monomeric or polymeric plasticizers for coatings and plastic film and sheeting (49). They are compatible with, and useful ia, ceUulosics, vinyls, polystyrenes, and some other plastics. 

Chemical Composition. From the point of view of leathermaking, hides consist of four broad classes of proteins coUagen, elastin, albumen, and keratin (3). The fats are triglycerides and mixed esters. The hides as received in a taimery contain water and a curing agent. Salt-cured cattie hides contain 40—50% water and 10—20% ordinary salt, NaCl. Surface dirt is usuaUy about 2—5 wt %. Cattie hides have 5—15% fats depending on the breed and source. The balance of the hide is protein (1). 

Uses. Phthabc anhydride is used mainly in plasticizers, unsaturated polyesters, and alkyd resins (qv). PhthaUc plasticizers consume 54% of the phthahc anhydride in the United States (33). The plasticizers (qv) are used mainly with poly(vinyl chloride) to produce flexible sheet such as wallpaper and upholstery fabric from normally rigid polymers. The plasticizers are of two types diesters of the same monohydric alcohol such as dibutyl phthalate, or mixed esters of two monohydric alcohols. The largest-volume plasticizer is di(2-ethylhexyl) phthalate [117-81-7] which is known commercially as dioctyl phthalate (DOP) and is the base to which other plasticizers are compared. The important phthahc acid esters and thek physical properties are Hsted in Table 12. The demand for phthahc acid in plasticizers is naturally tied to the growth of the flexible poly(vinyl chloride) market which is large and has been growing steadily. 

Mixed esters can be prepared from Cl Ti(OR)4 and a second alcohol in the presence of a base or by mixing a tetraalkoxide and the second alcohol in the desired proportions and flash-evaporating the mixed alcohols. Mixing of two pure tetraalkoxides of titanium also leads, via a rapid ester interchange reaction, to a mixture of ah. possible combinations of tetraalkyl titanates. 

Also produces cellulose acetate butyrate (CAB) and cellulose acetate propionate (CAP) mixed esters. 

Cellulose esters of aromatic acids, aUphatic acids containing more than four carbon atoms and aUphatic diacids are difficult and expensive to prepare because of the poor reactivity of the corresponding anhydrides with cellulose Httle commercial interest has been shown in these esters. Of notable exception, however, is the recent interest in the mixed esters of cellulose succinates, prepared by the sodium acetate catalyzed reaction of cellulose with succinic anhydride. The additional expense incurred in manufacturing succinate esters is compensated by the improved film properties observed in waterborne coatings (5). 

Mixed esters containing the dicarboxylate moiety, eg, cellulose acetate phthalate, are usually prepared from the partially hydroly2ed lower aUphatic acid ester of cellulose in acetic acid solvent by using the corresponding dicarboxyhc acid anhydride and a basic catalyst such as sodium acetate (41,42). Cellulose acetate succinate and cellulose acetate butyrate succinate are manufactured by similar methods as described in reference 43. 

Other mixed esters, eg, cellulose acetate valerate [55962-79-3] cellulose propionate valerate [67351-41-17, and cellulose butyrate valerate [53568-56-2] have been prepared by the conventional anhydride sulfuric acid methods (25). Cellulose acetate isobutyrate [67351-38-6] (44) and cellulose propionate isobutyrate [67351-40-0] (45) have been prepared with a 2inc chloride catalyst. Large amounts of catalyst and anhydride are required to provide a soluble product, and special methods of delayed anhydride addition are necessary to produce mixed esters containing the acetate moiety. Mixtures of sulfuric acid and perchloric acid are claimed to be effective catalysts for the preparation of cellulose acetate propionate in dichi oromethane solution at relatively low temperatures (46) however, such acid mixtures are considered too corrosive for large-scale productions. 

The price of cellulose ester flake has generally increased with inflation and as of mid-1987 was estimated at ca 3.64— 4.71/kg for cellulose diacetate molding resin and from ca 4.16— 4.71/kg for the mixed esters molding resins depending on purity and the number of propionyl or butyryl esters (4). 

From 1946 to mid-1987, Farbenfabriken Bayer AG in Germany was the European producer of cellulose acetate, cellulose acetate butyrate (CAB), and cellulose acetate propionate (CAP) before closing its faciUties. Bayer s exit from the cellulose acetate mixed esters business leaves Eastman Chemical Co. in the United States as the sole producer of CAB/CAP resins. 

Cellulose esters, especially acetate propionate and acetate butyrate mixed esters, have found limited use in a wide variety of specialty appHcations such as in nonfogging optical sheeting (171), low profile additives to improve the surface characteristics of sheet-molding (SMC) compounds and hulk-molding (BMC) compounds (172,173), and controlled dmg release via encapsulation (174). 

Mixed esters such as cellulose acetate sulfate [51910-28-2] (21,22), cellulose acetate butyrate sulfate [57485-48-0] (21,22), cellulose acetate propionate sulfate [67351-39-7] (23), and ethylceUulose sulfate (24) are described in the patent Hterature but are not of commercial importance. 

Oils are mixtures of mixed esters with different fatty acids distributed among the ester molecules. Generally, identification of specific esters is not attempted instead the oils are characterized by analysis of the fatty acid composition (8,9). The principal methods have been gas—Hquid and high performance Hquid chromatographic separation of the methyl esters of the fatty acids obtained by transesterification of the oils. Mass spectrometry and nmr are used to identify the individual esters. It has been reported that the free fatty acids obtained by hydrolysis can be separated with equal accuracy by high performance Hquid chromatography (10). A review of the identification and deterrnination of the various mixed triglycerides is available (11). 

Broinonaphlhalene (9). in the same manner the acyl chloride 6 was reacted with hydroxamic denvative 7 to give the mixed ester 8, which heated In BrCCIa/PhCI In the presence of azolsobutyronitnle (AIBN) at 130°C afforded 9 in 85% yield. 

A s/cr.s possess a fruity smell and usually distil without decomposition. Boil with refltiK for 5 minutes on the water-btith a few c.c. of the licpiid with 3 to 4 volumes of a ten pei cent, solution of ctLListic potash in methyl alcohol and pour into water. Notice if the liquid dissolves and has lost the odour of the ester. An ester will be completely hydrolysed, and if the alcohol is soluble in water a clear solution will be obtained. If the alcohol is vol.atile and the solution neiitialised w ith sulphuric acid. and evaporated on the water-bath, the alkali salt of the organic acid mixed with pottissium sulphate will be left and the acid may be investigated as desciibed under 1. If it is required to. ascertain the nature of the alcohol in the ester, hydrolysis must fig effected with a strong aqueous solution of caustic potash... 

Meerwein s Ester (9) Dimethyl malonate (13.2 g, 0.4 mole) and 6 g of 40 % aqueous formaldehyde solution are mixed in an Erlenmeyer flask and cooled to 0° in an ice bath. To the mixture is added 0.3 g of piperidine and enough ethanol to produce a homogeneous solution. The solution is allowed to stand at 0° for 12 hours, at room temperature for 24 hours, and at 35 0° for 48 hours. The reaction product is washed with water (50 ml) followed by dilute sulfuric acid, then dried (sodium sulfate). Unreacted malonic ester is distilled off under vacuum leaving a residue of about 12.5 g, which contains methylenemalonic ester, methylenebismalonic ester, and hexacarbomethoxypentane. 

Common fats (butter, tallow) and oils (olive, palm, and peanut) are mixed esters each molecule has most often three, sometimes two, or, rarely, one kind of acid combined with a single glycerol. There are so many such combinations in a given sample that fats and oils do not have sharp melting or boiling points. Ranges are found instead. 

Chemical properties. As already stated, Petrin is an intermediate in the prepn of numerous mixed esters. Marans et al (Ref 2) prepd a series of Petrin-nitrobenzoate esters by reacting Petrin with the appropriate nitrobenzoyl chloride. They also prepd Petrin-formate, acetate, propionate, oxalate, glutarate, succinate, adipate, and phthalate. An especially important Petrin derivative is Petrin-acrylate. It is prepared by reacting Petrin with a mixt of acrylyl chloride and dimethylaniline (Ref 4)... 

The influence on detergency of mixing ester sulfonates with different chain lengths has been studied with sodium methyl a-sulfopalmitate (C16 ester sulfonate) and sodium methyl a-sulfostearate (C18 ester sulfonate) [58]. At 20°C... 

Acid anhydrides have been employed with, and without the use of a base catalyst. For example, acetates, propionates, butyrates, and their mixed esters, DS of 1 to ca. 3, have been obtained by reaction of activated cellulose with the corresponding anhydride, or two anhydrides, starting with the one with the smaller volume. In all cases, the distribution of both ester groups was almost statistic. Activation has been carried out by partial solvent distillation, and later by heat activation, under reduced pressure, of the native cellulose (bagasse, sisal), or the mercerized one (cotton linters). No catalyst has been employed the anhydride/AGU ratio was stoichiometric for microcrystalhne cellulose. Alternatively, 50% excess of anhydride (relative to targeted DS) has been employed for fibrous celluloses. In all cases, polymer degradation was minimum, and functionalization occurs preferentially at Ce ( C NMR spectroscopic analysis [52,56,57]). 

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