Condensation esterification

Under the general term of substitution, we will deal with several transformations in which two molecules of reactants form the product and in which a new C—C or C—O bond or bonds are formed by replacing a C—H bond or another C—O bond. Aldol condensation, esterification, or transesterification and the formation of ethers from alcohols fall into this broad category. We also will include in this section addition to multiple C—C bonds. The published LFERs are summarized in Table III (2, 72-76). 

A new transesterification stanoxane catalyst, tin (di(chlorodimethylsiloxy)-tin chlor-odimethylsilane), has been used to incorporate ethyl acrylate into the condensation polymer of 2,2-bis(hydroxymethyl)propionic acid. This catalyst is preferable because it allows the reaction to proceed under milder conditions than those using a condensation esterification reaction route and makes it likely for product crosslinking side reactions to occur. 

For catalysis by bases, addition esterification is the first and the fastes reaction. It can be followed by slower polyetherification reaction, if epoxy groups are in excess, or by condensation esterification (even slower), if carboxyl groups are in excess. This mechanism was verified on a model system caproic acid — phenylglycidyl ether... 

Aluminum chloride and its derivatives are the most familiar Lewis acids and are routinely employed in many Lewis acid-promoted synthetic transformations. The first polymer-supported metal Lewis acids to be studied were polymers attached by weak chemical or physical interactions to a Lewis acid. In the 1970s Neckers and coworkers reported the use of styrene-divinylbenzene copolymer-supported AlCl,- or BF3 as catalyst in condensations, esterifications, and acetalization of alcohols [11,12]. This type of polymer-supported AICI3 (1) is readily prepared by impregnation of a polystyrene resin with AICI3 in a suitable solvent. Subsequent removal of the solvent leaves a tightly bound complex of the resin and AICI3. The hydrophobic nature of polystyrene protects the moisture-sensitive Lewis acid from hydrolysis, and in this form the Lewis acid is considerably less sensitive to deactivation by hydrolysis. This polymer complex could be used as a mild Lewis acid catalyst for condensation of relatively acid-sensitive dicyclopropylcarbinol to an ether (Eq. 1) [13],... 

Bixchler Napiralski, Dieckmann cyclization [15], Suzuki reaction [48], Wittig reaction, ozonolysis, condensation, esterification, nucleophilic substitution [49], Henry reaction, 1.3-dipolar cyclo-addition, electrophilic addition [50], oxidation chloride -> aldehyde [50], sulfide —> sulfone [51], alcohol —> ketone, Arbuzov reaction (phosphine-phosphorox-ide) [52], reduction hydration [45], ester -> alcohol [49, 53]... 

To avoid tedious reaction workup, polystyrene-supported AICI3 (72) was first developed by Neckers and coworkers [42]. After their pioneering work, polystyrene-supported AICI3 has been used for various chemical transformations including condensation, esterification, and acetalization of alcohols [42]. Some other applications were discussed in the previous edition of this book [18]. Application of this... 

Free Radical Active hydrogen Vinyl Addition Urethane Carbodiimide Condensation Esterification... 

Hierarchical (or mesoporous) zeolites became the focus of the review by Christensen et al. [7]. The main reason behind the development of hierarchical zeolites is to achieve heterogeneous catalysts with an improved porous structure and thereby enhanced performance in alkylation of benzene with alkenes, alkylation, and acylation of other compounds, methanol conversion into hydrocarbons, aromatization processes, isomerization of paraffins, cracking of diverse substrates and raw materials (naphtha, aromatic compounds, hexadecane, vacuum gas oil, and some polymers), and hydrotreating. The reactions that are of interest from the point of view of fine chemicals synthesis occurring on hierarchical zeohtes include aldol condensation, esterification, acetalization, olefin epoxidation, and Beckmarm rearrangement. 

The reaction mechanisms between the epoxy group and the carboxyl and hydroxyl groups have been studied and three different reaetions - two esterifications and one etherification -are identified [21]. The results of DSC, FTIR and reaction mechanisms indicate that the cin-ing process between the epoxy resin and GMAEVC can be explained by condensation esterification (carboxyl-hydroxyl reaction), addition esterification (carboxyl-epoxy reaction) and etherification (hydroxyl-epoxy reaction) from lower temperature to higher temperature. 

Ethyl p-aminobenzoate (esterification of p-aminobenzoic acid). Place 80 ml. of absolute ethyl alcohol in a 250 ml. conical flask equipped with a two-holed cork and wash-bottle tubes. Pass dry hydrogen chloride (Section 11,48,2) through the alcohol until saturated—the increase in weight is about 20 g.—and transfer the solution to a 250 ml. round-bottomed flask. Introduce 12 g. of p-aminobenzoic acid, fit a double surface condenser to the flask, and reflux the mixture for 2 hours. Upon... 

Benzilic acid rearrangement Benzoin reaction (condensation) Blanc chloromethylation reaction Bouveault-Blanc reduction Bucherer hydantoin synthesis Bucherer reaction Cannizzaro reaction Claisen aldoi condensation Claisen condensation Claisen-Schmidt reaction. Clemmensen reduction Darzens glycidic ester condensation Diazoamino-aminoazo rearrangement Dieckmann reaction Diels-Alder reaction Doebner reaction Erlenmeyer azlactone synthesis Fischer indole synthesis Fischer-Speior esterification Friedel-Crafts reaction... 

Acid catalyzed condensation of an alcohol and a carboxylic acid yields an ester and water and IS known as the Fischer esterification... 

Fischer esterification m which a phenol and a carboxylic acid condense m the pres ence of an acid catalyst is not used to prepare aryl esters... 

Chemical Properties. Neopentyl glycol can undergo typical glycol reactions such as esterification (qv), etherification, condensation, and oxidation. When basic kinetic studies of the esterification rate were carried out for neopentyl glycol, the absolute esterification rate of neopentyl glycol with / -butyric acid was approximately 20 times that of ethylene glycol with / -butyric acid (7). 

Titanium alkoxides are used for the hardening and cross-linking of epoxy, siUcon, urea, melamine, and terephthalate resins in the manufacture of noncorrodable, high temperature lacquers in the sol-gel process as water repellents and adhesive agents (especially with foils) to improve glass surfaces as catalyst in olefin polymeri2ation, and for condensation and esterification. 

Solvent Process. In the solvent process, or solvent cook, water formed from the reaction is removed from the reactor as an a2eotropic mixture with an added solvent, typically xylene. Usually between 3 to 10 wt % of the solvent, based on the total charge, is added at the beginning of the esterification step. The mixed vapor passes through a condenser. The condensed water and solvent have low solubiUty in each other and phase separation is allowed to occur in an automatic decanter. The water is removed, usually to a measuring vessel. The amount of water collected can be monitored as one of the indicators of the extent of the reaction. The solvent is continuously returned to the reactor to be recycled. Typical equipment for this process is shown in Figure 2. The reactor temperature is modulated by the amount and type of refluxing solvent. Typical conditions are ... 

The 1 1 molar addition products of a primary diol and a tetraaLkyl titanate, Ti(OGO)(OR)2 may react with water to give either Ti(OGO)(OH)2 or condensed products (Ti(OGO)O), which can be used as esterification catalysts (64). 

The toluenesulfonic acid prepared as an iatermediate ia the preparation ofpara-cmso also has a modest use as a catalyst for various esterifications and condensations. Sodium salts of the toluenesulfonic acids are also used ia surfactant formulations. Annual use of toluene for sulfonation is ca 100,000-150,000 t (30-45 x 10 gal). 

Because vanillin is a phenol aldehyde, it is stable to autooxidation and does not undergo the Cannizzarro reaction. Numerous derivatives can be prepared by etherification or esterification of the hydroxy group and by aldol condensation at the aldehyde group. AH three functional groups in vanillin are... 

Isobutyraldehyde also undergoes consecutive aldol and Tischenko condensations to give 2,2,4-trimethyl-l,3-pentanediolmonoisobutyrate [25265-77-4] (Texanol, Filmer IBT), alternatively prepared by the esterification of TMPD with isobutyric acid. 

About 69% of the total 1988 U.S. consumption of isobutyraldehyde, went into the production of isobutyl alcohol and isobutyraldehyde condensation and esterification products. The other principal isobutyraldehyde derivative markets (as a percentage of total 1988 U.S. isobutyraldehyde consumption) are neopentyl glycol (15%) isobutyl acetate (6%) isobutyric acid (5%) isobutyUdene diurea (2.5%) and methyl isoamyl ketone (1.7%). 

Acid—Base Catalysis. Inexpensive mineral acids, eg, H2SO4, and bases, eg, KOH, in aqueous solution are widely appHed as catalysts in industrial organic synthesis. Catalytic reactions include esterifications, hydrations, dehydrations, and condensations. Much of the technology is old and well estabhshed, and the chemistry is well understood. Reactions that are cataly2ed by acids are also typically cataly2ed by bases. In some instances, the kinetics of the reaction has a form such as the following (9) ... 

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