Vinyl Butyrate, Reaction

Poly(vinyl Butyral). Poly(vinyl butyral) is prepared according to the following reaction ... 

Analogously, poly(vinyl ketals) can be prepared from ketones, but since poly(vinyl ketals) are not commercially important, they are not discussed here. The acetalization reaction strongly favors formation of the 1,3-dioxane ring, which is a characteristic feature of this class of resins. The first of this family, poly(vinyl ben2al), was prepared in 1924 by the reaction of poly(vinyl alcohol) with ben2aldehyde in concentrated hydrochloric acid (2). Although many members of this class of resins have been made since then, only poly(vinyl formal) [9003-33-2] (PVF) and poly(vinyl butyral) [63148-65-2] (PVB) continue to be made in significant commercial quantities. 

Poly(vinyl alcohol) participates in chemical reactions in a manner similar to other secondary polyhydric alcohols (82—84). Of greatest commercial importance are reactions with aldehydes to form acetals, such as poly(vinyl butyral) and poly(vinyl formal). 

Poly(vinyl butyral), prepared by reacting poly(vinyl alcohol) with -butyraldehyde, finds wide appHcation as the interlayer in safety glass and as an adhesive for hydrophilic surfaces (161). Another example is the reaction of poly(vinyl alcohol) with formaldehyde to form poly(vinyl formal), used in the production of synthetic fibers and sponges (162). 

Reaction of poly(vinyl alcohol) [9002-89-5] with //-butyraldehyde yields poly(vinyl butyral) [63148-65-2] (PVB), a commercially important resia. 

An industrial example of acidolysis is the reaction of poly(vinyl acetate) with butyric acid to form poly(vinyl butyrate). Often a butyric acid—methanol... 

Transesterification has a number of important commercial uses. Methyl esters of fatty acids are produced from fats and oils. Transesterification is also the basis of recycling technology to break up poly(ethylene terephthalate) [25038-59-9] to monomer for reuse (29) (see Recycling, plastics). Because vinyl alcohol does not exist, poly(vinyl alcohol) [9002-89-5] is produced commercially by base-cataly2ed alcoholysis of poly(vinyl acetate) [9003-20-7] (see Vinyl polymers). An industrial example of acidolysis is the reaction of poly(vinyl acetate) with butyric acid to form poly(vinyl butyrate) [24991-31-9]. 

The products are amorphous resins whose rigidity and softening point depend on the aldehyde used. Poly(vinyl butyral), with the larger side chain, is softer than poly(vinyl formal). Since the reaction between the aldehyde and the hydroxyl groups occurs at random, some hydroxyl groups become isolated and are incapable of reaction. A poly(vinyl acetal) molecule will thus contain ... 

In the reaction, it was essential to use an IL as a co-solvent. Lozano, Iborra and co-workers recently reported an interesting stabilizing effect of two types of water-immiscible ILs ([emim][TFSI] and [BuMe3N][TFSI]) for CAL-B-catalyzed transesterification of vinyl butyrate. The synthetic activity and the stability of the enzyme in these IL solvent systems were markedly enhanced as compared to those in hexane. CAL-B maintained its activity higher than 75% after 4 days of incubation in [emim][TFSI] solvent, while it showed an activity of only 25% when incubated in both water and hexane media at 50°C. Comparison of the ratio of a-helix and (3-sheet by CD spectra showed the activity was closely related with a-helix content which reduced to 31% immediately after lipase was added to hexane and had reached only 2% after 4 days in hexane. On the contrary, no significant reduction of a-helix content was... 

Reaction in organic solvent can sometimes provide superior selectivity to that observed in aqueous solution. For example, Keeling et al recently produced enantioenriched a-trifluoromethyl-a-tosyloxymethyl epoxide, a key intermediate in the synthetic route to a series of nonsteroidal glucocorticoid receptor agonist drug candidates, through the enan-tioselective acylation of a prochiral triol using the hpase from Burkholderia cepacia in vinyl butyrate and TBME (Scheme 1.59). In contrast, attempts to access the opposite enantiomer by desymmetrization of the 1,3-diester by lipase-catalysed hydrolysis resulted in rapid hydrolysis to triol under a variety of conditions. 

Vinyl coatings are used primarily on metal surfaces. They provide excellent protection by their strong cohesive forces, although their adhesion to the metal is not good. Used with a phosphoric acid-containing primer to etch the metal surface, this adhesion is markedly improved. The primer also contains poly(vinyl butyral) and is approximately 0.2-0.3 mil thick (1 mil = 1/1000th inch). Poly(vinyl butyral) is made from polymerized vinyl acetate by hydrolysis and reaction with butyraldehyde. 

This safety glass turned yellow after several years of exposure to light. The bonding layer was replaced in 1933 by cellulose acetate, made from the reaction of cotton with acetic acid. By 1939 this was replaced by poly(vinyl butyral) (PVB), which is still in use today as the adhesive placed between sheets of glass to produce laminated safety glass. This is one of a very few modern-use materials that has retained the same basic materials for over 60 years. 

Early reports on the effects of the choice of solvent on enzymatic enantioselectivity showed that substantial changes may be observed. For the transesterification reaction of sec-phenethyl alcohol with vinyl butyrate catalyzed by subtilisin Carlsberg, a 20-fold increase in the E-value was reported when the medium was changed from acetonitrile to dioxane [59]. Similar changes were recorded for the prochiral selectivity of Pseudomonas sp. lipase in the hydrolysis of 2-substituted... 

The synthesis of poly(vinyl acetals) (252) represents another example of generating a heterocycle, in this case the 1,3-dioxane nucleus, by application of a polymer modification reaction. Generally, the polymer modified is poly(vinyl alcohol) (180) or one of its copolymers. The 1,3-dioxane ring is generated (Scheme 122) by an acid-catalyzed acetalization reaction with an aldehyde, although ketones have also been reacted. A review (71MI11102) is available covering synthesis, properties and applications of the two most common and industrially important poly(vinyl acetals), poly(vinyl butyral) and poly(vinyl formal), as well as many other functional aldehydes that have been attached. 

The bicyclic aminoalcohol, 3-quinuclidinol, is an important synthon for the preparation of cholinergic receptor ligands [23], anesthetics [24], and drugs for the treatment of Alzheimer s disease and asthma [5]. P. Bossard at Lonza AG developed and patented an enantioselective acylation of racemic 3-quinuclidinol using ChiroCLEC -BL, the CLC form of subtilisin (Fig. 5) [25]. The reaction was run in 2-methyl-3-butanol with vinyl butyrate used as the acylating agent. 

Lipase-catalyzed acylation of one isomer of iV-hydroxymethyl /3-lactam 121 by vinyl butyrate in acetone yielded the ester 122, which afforded 123 after acidic hydrolysis and ion-exchange chromatography (Scheme 7). The unesterified alcohol 124 gave the /3-amino acid 125. Similar reactions yielded 2-aminocyclohex-3-en-l-carboxylic acid and 2-aminocyclohex-4-ene-l-carboxylic acid from l-azabicyclo[4.2.0]oct-3-en-8-one and l-azabicyclo[4.2.0]oct-... 

Table 9.3 Initial reaction rates and the fraction of ester present under the form of monoester for the acylation of various polyhydroxylated natural compounds (30mM) with vinyl butyrate catalyzed by immobilized CALB in [bmim]BF4 and [bmimJPFs at 60°C and in acetone at 50°C after 72h of reaction.

TRANSESTERIFICATION REACTION OF VINYL BUTYRATE WITH BENZYL ALCOHOL IN ANHYDROUS CARBON TETRACHLORIDE CATALYSED BY DIFFERENT HYDROLYTIC ENZYMES IMPRINTED WITH THE SUBSTRATE ANALOGUE V-ACETYL-L-PHENYLALANINE AMIDE ... 

Assuming that the yield for gel fraction is proportional to the rate of crosslinking, it seemed that the observation on possibility of resolving the experimental results into terms proportional to I and Ia /2, points out the dual mechanism of photoinduced crosslinking of poly (vinyl butyral). The over all character of the equation (l) suggests that the main role in the discussed reaction plays the relation gel content connected possibly with direct coupling of... 

The -0-R group attached to the carbon chain backbone of a polymer is also present in acetals. These polymers can be obtained, for example, from poly(vlnyl alcohol) and an aldehyde in the presence of a strong acid. Typically the reaction starts with poly(vinyl acetate), which is saponified in methanol with NaOH to generate the PVA, followed by the acetal formation. This sequence of reactions is shown below for the formation of poly(vinyl butyral) ... 

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