Dibasic esters, formation

DnoouFosmoN voltage, 2. Dehydration by electro-osmosis, SO. Deoxyoafieine, formation of, 63. Dibasic esters, formation of, 72. Diazotisation by electrolyds, 71. 

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... 

A continuous process for the production of high dropping point lithium complex greases has been developed (13). Here, the conventional dibasic acid salt or the dibasic ester component is no longer used. These conventional components are substituted with a borated additive fed into the reactor downstream of the thickener formation zone. This substitution and process modification results in a significantly less problematic process and a substantial increase in production throughput (13). 

Other constituents may be added to assist in the formation of uniform beads or to influence the use properties of the polymers through plasticization or cross-linking. These include lubricants, such as lauryl or cetyl alcohol and stearic acid, and cross-linking monomers such as di- or trivinylbenzene, diaHyl esters of dibasic acids, and glycol dimethacrylates. 

The primary and secondary alcohol functionahties have different reactivities, as exemplified by the slower reaction rate for secondary hydroxyls in the formation of esters from acids and alcohols (8). 1,2-Propylene glycol undergoes most of the typical alcohol reactions, such as reaction with a free acid, acyl hahde, or acid anhydride to form an ester reaction with alkaU metal hydroxide to form metal salts and reaction with aldehydes or ketones to form acetals and ketals (9,10). The most important commercial appHcation of propylene glycol is in the manufacture of polyesters by reaction with a dibasic or polybasic acid. 

Berberilic acid, CgoHjgOgN, m.p. 177-82°, is dibasic, and furnishes a dimethyl ester, m.p. 173°. When heated to about 180°, the acid passes into ANHYDROBERBERiLic ACID, CjgHjjOgN, colourless needles, m.p. 236°, soluble in alkali carbonate solutions with the formation of berberilates. When ammonium berberilate is dried under reduced pressure, a molecular proportion of ammonia is lost with the formation of the ammonium salt of the anhydro-acid, from which other salts, and the methyl ester, m.p. 178°, have been obtained. Berberilic acid is hydrolysed by hot dilute sulphuric acid to hemipinic acid (I) and oi-aminoethylpiperonylic acid (II), large tabular crystals, m.p. 180-2°. Berberilic acid is therefore represented by (III). 

Sulfuric acid can form ester derivatives with alcohols, though since it is a dibasic acid (pAla — 3, 2) it can form both mono- and di-esters. Thus, acid-catalysed reaction of methanol with sulfuric acid gives initially methyl hydrogen sulfate, and with a second mole of alcohol the diester dimethyl sulfate. Though not shown here, the mechanism will be analogous to the acid-catalysed formation of carboxylic acid esters (see Section 7.9). 

Formic anhy dride is not stable. However, formate esters of alcohols and phcnolics can be prepared using lormic-acetic anhydride. Dibasic acid anhydrides such as phthalic anhydride and maleic anhydride readily react with alcohols to form Ihe numoalkyl ester Kelene, like acid anhydrides, reacts with alcohols to fonn (acctatei esters. 

Carboalkoxy acyl halides are made from mono esters of dibasic acids and thionyl chloride or phosphorus pentachloride. Examples are numerous. Halides with the ester group in the beta position are unstable to prolonged heating. Alkyl halide is eliminated with the formation of an anhydride. Under certain conditions a rearrangement occurs in the preparation of ester acid chlorides. The product obtained is a mixture of the expected compound and its isomer in which the ester and acid chloride groups are interchanged, viz., ROjCCHR (CI ) CO,H — RO,C(CH,) CHR COQ. The cyclic anhydride is a likely intermediate. ... 

The method has been adapted to the formation of l)fs-diazoacetylalkanes from dibasic acid chlorides. Diazo ketones have been obtained from acyl chlorides containing a /Sj y-double bond, an ester group, and certain heterocyclic and aryl nuclei having alkyl, methoxyl, and nitro substituents. On the other hand, functional groups such as phenolic hydroxyl, arylamino, aldehyde, active methylene, and a,/S-unsaturated linkages may interfere. The method is ideal for application to complex molecules. 

The gross structure of seneciphyllic acid was established by Adams et al. (205). It was shown to be dibasic by direct titration and by formation of a dimethyl ester. The IR-maximum at 3452 cm. and at 3497 cm.- for the acid and its ester was indicative of a hydroxyl group, which because of its inertness was recognized as tertiary and because of the yellow color given by seneciphyllic acid with ferric chloride was... 

Formation of di-esters of dibasic acids. Succinic acid — Adipic acid—Suberic acid—Sebasic acid—n-Dodecane-dicarboxylic acid—n-Decahexane-dicarboxylic acid.37-38... 

A convenient source of esterase for in vitro laboratory use is malt enzyme (diastase, J. P.) the application of which was described by Noguchi (N-672, N-673). Noguchi reported the successful hydrolysis of acetates at the IBa-, 17/3-, 20a-, 20/3-, and 21-positions (N-672). He also extended this method to 21-esters of other straight-chain aliphatic carboxylic acids (formate, butyrate, and caprylate), dibasic aliphatic hemiesters (hemisuccinate and hemitartrate) and JV-substituted amino acid esters (diraethylaminoacetate and diethylaminoacetate) (N-673). 17/3-Formate was hydrolyzed, t 17/3-propionate was not. 

Different types of chemical compounds such as vegetable oils, fatty adds, dibasic acids and anhydrides, dihydroxyamine and catalysts are required for the preparation of vegetable oil-based poly(ester amide)s. The methods of resinification or polymer formation are similar to those of vegetable oil-based polyesters, as discussed in the earlier chapter (Chapter 4). 

In mixtures, 2-nonenal and 2,4-heptadienal are more rapidly oxidized than methyl linoleate and linolenate, and these fatty esters are more readily oxidized than nonanal. Therefore, during the more advanced stages of oxidation the saturated aldehydes accumulate and the unsaturated aldehydes are further oxidized to lower aldehydes and dialdehydes. At elevated temperatures, saturated aldehydes and dialdehydes are further oxidized into mono- and dibasic acids. The formation of low molecular weight volatile acids is used as a measure of thermal oxidation of fats, and is the basis for detection in some high temperature stability tests (Chapter 7). 

---