Anhydrides, reaction with

Yuan et al [60] have described an elegant method to hydrophobize the surface of tunicin whiskers. Aqueous emulsions of an alkenyl succinic anhydride were mixed with cellulose whisker suspensions, freeze-dried and then heated. Bulk and surface D S was evaluated by FT-IR and XPS, respectively. DS values were low ( 0.02), but this 

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Hydrogen peroxide undergoes two reactions with anhydride ... 

Reactions with anhydrides afford interesting compounds having a carboxylic acid function (Table 26, entries 5 and 7 and Figure 40). It is notable that in the case of succinic anhydride, if the reaction is carried out at 25 °C, only one substitution occurs on the nitrogen atom, if the temperature is increased to 180 °C, there is a second substitution giving rise to a heterocyclic substituent (Table 26, entries 5-8). 

For all the reactions with anhydrides it is preferable to use the free amine rather than the hydrochloride salt in order to reduce the amount of external base in the reaction mixture and thus obtain clean products. 

Since amines react more readily than alcohols in noncatalyzed reactions with anhydrides, the reaction is more difficult and initially required stoichiometric catalyst loadings [107], but could be performed in a catalytic sense with an O-acylated azlactone as acylating agent, which does not react with a benzylic amine at —50°C, but is capable of acylating the catalyst [108, 109]. Depending on the buUdness of the substrate, selectivities ranged from S = 11 to 27 (s = [ enantiomer l]/[ enantiomer 2])-... 

Some support for this mechanism is provided by the observation that on reaction with anhydrides of the form (R2CHC0)20—where there would be no a -H to remove in the intermediate corresponding to (1066)—it is possible to isolate the analogue of (1066) as the actual end-product of the reaction. 

PEG contains no carboxylate groups in its native state, but can be modified to possess them by reaction with anhydride compounds. Either PEG or mPEG may be acylated with anhydrides... 

Scheme 156 Nickel-zinc-mediated cathodic Reformatsky reaction with anhydrides.

Reactions with anhydrides and acid chlorides are more rapid and can occur in an essentially nonreversible fashion. But, anhydrides and acid chlorides are considered high-energy reactants since they often involve additional energy-requiring steps in their production, and are thus less suitable for large-scale production of materials. The activity energies for direct esterification and transesterification are on the order of 30 kcal/mol (120 kJ/mol) while the activation energies for anhydride and acid chloride reaction with alcohols are on the order of 15-20 kcal/mol (60-80 kJ/mol). 

For a review of the reactions with anhydrides and imides (and carboxylic esters, thiol esters, and amides), see Murphy Brennan Chem. Soc. Rev. 1988,17, 1-30. For a review with respect to imides, see Flitsch Schindler Synthesis... 

A number of nitrogen- and sulfur-containing heterocyclic compounds are effective corrosion inhibitors (62MI11502), the imidazolines and the benzotriazoles being particularly important types. The imidazolines are derived from ethyleneamines by reaction with fatty acids the free bases (53), the fatty acid salts (54), and various derivatives obtained by reaction with anhydrides, isocyanates or alkyl halides (55) are effective inhibitors. 

Oxidative ring expansion of enamides.2 A general route to tetrahydro-3-benz-izepine-2-ones involves oxidative ring expansion of enamides of dihydroisoquino-Imes, which are easily formed by reaction with anhydrides or acid chlorides. The... 

Styryl carbanions readily react with carbon dioxide 31) to yield carboxy end groups. These terminal groups are also introduced by reaction with anhydrides 19) whereas the use of oxirane 23) leads to the formation of hydroxy end groups esters and nitriles are used to introduce carbonyl functions at the chain end. These reactions can be carried out at low temperature in THF solution and proceed quantitatively if no deactivation by protons occurs. 

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