Octadienyl ether

Keywords Hydrophobic starch, Octadienyl ether, Palladium, Surfactant, Telomerization, Water catalyzed reaction... 

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. 

Glucose octadienyl ether (DS = 2) is non-toxic with good skin compatibility [73]. The viscosity of derivative with moderate degree of substitution (DS = 1.5) reaches 2500 cPs at 25°C and potential applications as emulsifiers or defoamers are conceivable. 

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. 

Abstract The dimerization of 1,3-dienes (e.g. butadiene) with the addition of a protic nucleophile (e.g. methanol) yields 2,7-octadienyl ethers in the so-called telomerization reaction. This reaction is most efficiently catalyzed by homogeneous palladium complexes. The field has experienced a renaissance in recent years as many of the platform molecules that can be renewably obtained from biomass are well-suited to act as multifunctional nucleophiles in this reaction. In addition, the process adheres to many of the principles of green chemistry, given that the reaction is 100% atom efficient and produces little waste. The telomerization reaction thus provides a versatile route for the production of valuable bulk and specialty chemicals that are (at least partly) green and renewable. The use of various multifunctional substrates that can be obtained from biomass is covered in this review, as well as mechanistic aspects of the telomerization reaction. 

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... 

Another important etherification is the palladium-catalyzed telomerization of glycerol with butadiene yielding octadienyl ethers of glycerol, which can be used as starting materials for detergents [51, 52]. 

The hnear dimerization of isoprene with alcohols also continues to be of inter-est,[27],[8i] [85] rough correlation between the yield of octadienyl ether and the acidity of the alcohol was noted.f " Thus, trifluoroethanol (pX, 12.39) and methanol (pX, 15.09) give high yields ethanol (pX 15.93), n-propanol (pX 16.1), and n-butanol (pX 16.1) give moderate yields while tert-butyl alcohol (pX >19) does not afford a hnear dimer. 

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. 

A soln. of piperidine and diisobutylaluminium chloride in methylene chloride treated with methyl 2,7-octadienyl ether in the presence of a little Pd(acac)2 and PPh3 at 35-40° for 6-8 h - product. Y 65-96%. F.e. and 2-ethylenethioethers (with Cp2ZrCl2) s. U.M. Dzhemilev et al., Izv. Akad. Nauk SSSR Ser. Khim. 1988, 2645. 

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 selective telomerization of 1,3-butadiene with seven different linear and cyclic diols in the presence of in situ generated (NHC)-Pd catalysts was reported by Beller and coworkers [82]. They showed that these telomerlzations could proceed with very low metal loadings (2-10 ppm Pd) and with excellent catalyst turnover numbers (>250000). Depending on the substrate, excellent conversions and high chemo-selectivities toward the mono-octadienyl ether were obtained. 

The telomerization reaction is catalyzed by various transition metal complexes as nickel, palladium or platinum, but among them, palladium catalysts proved to be the most efficient. With palladium catalysts, linear cis, trans and branched octadienyl ethers are the major products and side products that can arise from the linear dimerization or the degenerative telomerization of butadiene are formed in marginal amounts (Scheme 6). 

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. ... 

Conditions have been described whereby butadiene is dimerized to a mixture of octadienes, using N-hydroxymorphoIine and nickel(O) phosphine complexes/ or to octadienyl ethers using palladium catalysts in alcohol. In both cases minimal formation of octatriene products is observed. 

Starting from the very reactive Pd2(dae)3 (dae = diallyl ether), " an alternative route to other carbene complexes of palladium(O) has been reported recently. These are of the type Pd(carbene)(77 -dae), with differently substituted imidazol-2-ylidene molecules. Theoretical calculations and five X-ray diffraction structures were undertaken to analyze the electronic and steric factors responsible for the unprecedented catalytic efficiency of these compounds in the telomerization reaction of 1,3-butadiene with alcohols to give alkyl octadienyl ethers. 

The telomerization of various higher alcohols has also been carried out. The primary alcohols react most easily with butadiene, whereas secondary and tertiary alcohols yield only small amounts of telomers. Steric hindrance alone cannot be the only factor responsible for the reactivity because the voluminous 2,2-bis(trifluoromethyl)benzylalcohol reacts smoothly to produce the 2,7-octadienyl ether. 

Our objective was to prepare more hydrophobic starches to incorporate them in latex preparation for decorative paints so that substrates derived from fossil fuel can be replaced by modified starches derived from renewable resources. Partial substitution of starch with acetate, hydroxypropyl, alkylsiliconate or fatty-acid ester groups was described in the literature for the synthesis of more hydrophobic starch. An alternative route was employed consisting of grafting octadienyl chains by butadiene telomerization (8,9). This reaction (Figure 4) was catalyzed by hydrosoluble palladium-catalytic systems prepared from palladium diacetate and trisodium tris(m-sulfonatophenyOphosphine (TPPTS). Starch octadienyl ethers are expected to be much less sensitive towards hydrolysis compared to the esterified starches. 

The palladium(ii) acetylacetonate-tri phenyl phosphine catalysed reaction of butadiene with water and carbon dioxide in solvents such as t-butanol or acetone has been reported to give octa-2,7-dien-l-ol as the major product together with minor amounts of octa-l,7-dien-3-ol, 1,3,7-octatriene and octadienyl ethers. In contrast aqueous potassium tetrachloropalladate with excess diene leads to pale yellow solids which were polymeric. Decomposition of these complexes with dimethylglyoxime gave a mixture of 3-methyIbutenyl ethers, (Scheme 33). The use of (—)-2,2-dimethyl-4,5-bis(diphenylphosphinomethyl)-l,3-dioxolane (DIOP) as a chiral ligand... 

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