Sucrose octadienyl ethers

The sucrose octadienyl ethers have an average degree of substitution of 4—5.7 and are almost insoluble in water (Table 11). However, under such reaction conditions, the isopropanol reacted with the butadiene and 4—10% of isopropyloctadienyl ether were also observed. 

Sucrose (20) was also used for the reaction of telomerization with 1 [19, 49, 50]. Applying specific conditions, sucrose octadienyl ethers were obtained with an average degree of substitution of 4.7-5.3. These products are practically insoluble in water, clear or almost colorless, and present a viscosity of 1500-2000 cPs at 25°C [39]. These properties confer to these products the possibility of being employed as emulsifiers or defoaming agent [49]. Minimum surface tension of solution of substituted sucrose in water is 25-28 mN/m whatever the degree of substitution... 

Other Alkyl Ethers. Sucrose has been selectively etherified by electrochemical means to generate a sucrose anion followed by reaction with an alkyl halide (21,22). The benzylation of sucrose using this technique gives 2-O-benzyl- (49%), T-O-benzyl- (41%), and 3 -O-benzyl- (10%) sucrose (22). The benzylation of sucrose with benzyl bromide and silver oxide in DMF also produces the 2-O-benzyl ether as the principal product, but smaller proportions of T- and 3 -ethers (23). Octadienyl ether derivatives of sucrose, intermediates for polymers, have been prepared by a palladium-catalyzed telomerization reaction with butadiene in 2-propanol—water (24). 

The telomerization of sucrose with butadiene was catalyzed in aqueous solution by palladium acetate and tppts (102). The sucrose conversion was about 96%, but octadienyl ethers of different degrees of alkylation were also formed. 

Gruber B, Weese KJ, Mueller HP, Hill K, Behr A, Tucker IR, Hoagland SM (1992) Octyl ethers and octadienyl ethers of hydroxy compounds such as glucose and sucrose. WO 92/ 01702... 

Two recent studies have examined the selective monoalkylation and polyaUcylation of sucrose (Scheme 17, 52). Using Pd(acac)2/Ph3P, sucrose was efficiently polyalkylated with butadiene in 4 1 isopropanol/water to give a mixture of 2,7-octadienyl ethers averaging 4-5 ether linkages per sucrose.While conditions for polyalkylation were found, Mortreux and co-workers also reported an alternative set of conditions that favor selective monoaUcylation.t Treatment of sncrose (52) with Pd(OAc)2/3 TPPTS (TPPTS = tris(m-sulfonatophenyl)phosphine) in 5 2 isopropanol/1 M NaOH (80 °C, 30 min, 73% conversion) afforded a 2 1 mixture of mono- and diethers, from which monoethers 53a (65%) and 53b (18%) were isolated. The reaction is of interest for its selective alkylation, the use of a water-soluble catalyst system, and the observation that NaOH acts as a strong activator for the reaction. 

Carbohydrate allenyl ethers have been prepared via the corresponding propargyl ethos,and sucrose 0-octadienyl ethers have been synthesized by a novel telomerisation of butadiene with sucrose in the presence of Pd(acac>2 and PhsP. Radical bromination of allyl ethers using MBS in CCU in the presence of isopropylidene acetals, acetates and benzoates has allowed the selective removal of the allyl ethers with a hydrolytic work-up. ... 

The telomerization of sucrose has been studied more in depth. Using water alone as solvent, sucrose conversion was only 65% after 5 hours with 36% of mono and 48% of dioctadienyl compounds. The use of basic conditions (sodium hydroxide 1 M) resulted in a large increase of the catalytic activity for example, after only 26 minutes, 87% of sucrose was very selectively converted into octadienyl ethers with a higher average degree of substitution (DS = 2.4) (Scheme 11). Under these conditions, a turnover frequency of 5400 h could be observed after 20 min, at the maximum conversion rate. ... 

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