Sucrose-triethanolamines

The mixtures of sucrose - triethanolamine, usually of 1-1.5/1 (sucrose/triethanolamine) [9] are very stirrable mixtures, at the propoxylation temperature, and are frequently used in practice. Triethanolamine can be replaced by diethanolamine, monoethanolamine and even by ammonia [59]. The triol is formed in situ by the reaction of ammonia or primary or secondary ethanolamines with PO. The polyols based on sucrose - triethanolamine (Table 13.6) are frequently used to make rigid PU foams for thermoinsulation of freezers. The mixtures of sucrose - sorbitol lead easily to high functionality polyols, sorbitol having an excellent solvating capability for solid sucrose. 

This method of direct propoxylation of mixtures between sucrose and a second polyol is often used in practice, the most important polyols being based on sucrose - glycerol, sucrose - triethanolamine and sucrose - diethyleneglycol. 

Table 13.6 The characteristics of a representative sucrose-triethanolamine-based rigid polyether polyol for rigid PU foams (structure I) ...

Other polyhydric compounds with higher functionality than glycerol (three-OH) are commonly used. Examples are sorhitol (six-OH) and sucrose (eight-OH). Triethanolamine, with three OH groups, is also used. 

The most important low molecular weight polyols used as starters for polyether polyols destined for rigid PU foams synthesis are glycerol, trimethylolpropane (TMP), triethanolamine, pentaerythritol, dipentaerythritol, a-methyl glucoside, xylitol, sorbitol and sucrose [1-27]. The main properties of these starter polyols, which are of interest for polyurethane chemistry, are presented in Table 13.1. 

The representative examples are the synthesis of sucrose-based polyether polyols with a low melting point. Sucrose is well solvated by low molecular weight polyols such as glycerol, diethylene glycol, dipropylene glycol, triethanolamine and sorbitol. At the... 

One can easily imagine that if the glycerol is replaced by triethanolamine [9, 10] or by DEG [51], the resulting polyols are of course a mixture of propoxylated sucrose with propoxylated triethanolamine or propoxylated DEG (13.29). 

E3 UDP-sugar phosphorylase. E4 pyrophosphatase. (Below) Synthesis of 6 -deoxy-6 -fluorosucrose. El, sucrose synthetase E2, pyruvate kinase E3, UDP-glucose pyrophosphorylase E4, pyrophosphatase. All enzymes (150 U each) are co-immobilized in polyacrylamide gel. The reactions are carried out in triethanolamine buffer (50 mM) containing MgCl2 (10 mM) with pH being controlled at 7.5 by addition of IN NaOH. The 500-mL reaction mixture contains glucose-... 

Preparation of polyether polyols dispersions with high solids content and low viscosity from sucrose and propylene oxide with triethanolamine and tributylamine initiation [93],... 

Harms buffer 250 mM sucrose, 10 mM triethanolamine, 10 mM acetic add. 1 mM EDTApH73... 

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