Acetyl/hydroxypropyl groups

Acetylated starch 1420 E1420 Acetic anhydride Hydroxypropyl groups <7.0% Acetyl groups <2.5%... 

In the above condensation resist designs, the phenolic resin offers a reaction site as well as base solubility. Self-condensation of polymeric furan derivatives has been utilized as an alternative crosslinking mechanism for aqueous base development (Fig. 126) [375]. The copolymer resist is based on poly[4-hydroxy-styrene-co-4-(3-furyl-3-hydroxypropyl)styrene], which was prepared by radical copolymerization of the acetyl-protected furan monomer with BOCST followed by base hydrolysis. The furan methanol residue, highly reactive toward electrophiles due to a mesomeric electron release from oxygen that facilitates the attack on the ring carbons, readily yields a stable carbocation upon acid treatment. Thus, the pendant furfuryl groups serve as both the latent electrophile and the nucleophile. Model reactions indicated that the furfuryl carbocation reacts more preferentially with the furan nucleus than the phenolic functionality. 

Benzyloxypropyl)phosphonic and (2-trimethylsilyloxyethyl)phosphonic diethyl esters are obtained from the appropriate alkyl bromide and triethyl phosphite. Deprotection at the side-chain substituent (debenzylation with H2, Pd-C desilylation with MeOH-HCl) leaves the diethyl (2-hydroxypropyl)- and (2-hydroxyethyl)-phosphonates from which the free acids are readily obtainable by acid hydrolysis. Both procedures were adapted by Hammerschmidt for the preparation of deuterium-labelled compounds of known chirality for biosynthetic studies. The acetyl group can also be used for protection purposes ... 

Extended Hydrogen Bonding Groups Bonded P-Acetylated (CB-AC) and Bonded P-Hydroxypropylated Cyclodextrins (CB-SP), (CB-RSP),... 

The chemical substitution of hydroxyl groups with functional groups yields modified starches with unique functionalities and uses. Acetylated and hydroxypropylated starches are produced after treatment with anhydrous acetic and propylene oxide under an alkaline pH, respectively. After the reaction, the slurry is neutralized, filtered, and dried. These derivatized starches are less prone to retrogradation, produce weaker and clearer gels, and have improved water-holding capacity (Mauro et al. 2003, Thomas and Atwell 1999). 

Hydroxypropylation increases freeze-thaw stability, decreases gelatinization and pasting temperatures, and improves paste clarity. The hydroxyalkylated starches are obtained after treatment with alkylene oxide under alkaline conditions. The hydroxyl groups located in the second position of glucose units are the preferred sites of substitution. These starches have similar properties, functionalities, and uses as their acetylated counterparts (Table 13.1). 

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