Sodium iso-propoxide

Alfin An obsolete process for making synthetic rubber by polymerizing butadiene in pentane solution. The catalyst was an insoluble aggregate of sodium chloride, sodium iso-propoxide, and allyl sodium. The name is actually the name of the catalyst, derived from alcohol, used to make the sodium Aopropoxide, and olefin, referring to the propylene used to make the allyl sodium. 

T). 3 5)-Aminopyrazole Note 5). (Caution Because hydrogen gas is evolved, this reaction should be conducted in an efficient hood in the absence of an ignition source.) A solution of sodium iso-propoxide is prepared from 18.4 g. (0.80 g. atom) of sodium and 500 ml. of isopropyl alcohol in a 2-1. four-necked flask fitted with a mechanical stirrer, a thermometer, a reflux condenser, and a... 

The alkylmetal-metal alkoxide combination was first described by Morton [6] for the anionic polymerization of butadiene - addition of an equivalent of sodium iso-propoxide improved the catalytic activity of allylsodium. Fifteen years later the spe-... 

Secondary and tertiary alkyl halides are not suitable, because they tend to react with alkoxide bases by E2 elimination rather than by Sn2 substitution. Whether the alkoxide base is primary, secondary, or tertiary is much less important than the nature of the alkyl halide. Thus benzyl isopropyl ether is prepared in high yield from benzyl chloride, a primary chloride that is incapable of undergoing elimination, and sodium iso-propoxide ... 

Heat capacity measurements of sodium alkoxides (methoxide, ethoxide, n-propoxide and iso-propoxide) were carried out using DSC in die temperature range 240-550 K by Chandran and coworkers [219]. From the heat capacity values, odier thermodynamic functions, such as endialpy increments, entropies and Gibbs energy fimctions of these compounds were derived. The Cp 9g values of sodium medioxide, sodium ethoxide, sodium n-propoxide and sodium iso-propoxide were measured and reported. 

Sodium alkoxides, namely, sodium methoxide, sodium ethoxide, sodium n-propoxide, and sodium iso-propoxide were synthesized and characterized by various analytical techniques. Thermal decomposition of these sodium alkoxides was studied under isothermal and non-isothermal conditions by thermogravimetric (TG) method. Non-isothermal experiments were carried out at different linear heating rates. Mass spectrometric technique was followed for identifying the evolved gases. The onset temperatures of decomposition of sodium methoxide, sodium ethoxide, sodium n-propoxide, and sodium iso-propoxide were found to be 623, 573, 590, and 545 K, respectively. These sodium alkoxides form gaseous products of saturated and unsaturated hydrocarbons and leave a mixture of sodium carbonate, sodium hydroxide, and free carbon as the decomposition residue. Activation energy and pre-exponential factor for the decomposition reactions were deduced from the TG data by model-dependent and model-independent (iso-conversion) methods. The probable decomposition mechanism of sodiiun alkoxides is described in this chapter. 

Keywords-. Sodium methoxide, sodiiun ethoxide, sodium -propoxide, sodium iso-propoxide, decomposition, isothermal, non-isothermcd, activation energy... 

Literature survey The only study on the decomposition of sodium methoxide is a patent by Pfeifer et al. [36]. These authors have reported that the sodium methoxide decomposed at 393 and 413 K. The only study on the decomposition of sodium ethoxide has been reported by Blanchard et al. [19]. According to them, the decomposition commenced at temperatures above 570 K. There are no reports on the decomposition of other sodium alkoxides (for example, sodium n-propoxide and iso-propoxide). Even for sodium methoxide and sodium ethoxide, data on the kinetic parameters are not available. The kinetic parameters of the decomposition of sodium methoxide, sodium ethoxide, sodium n-propoxide and sodium iso-propoxide were determined and discussed in this chapter. 

The process of decomposition of sodium iso-propoxide commences at 550 K. In this case too the rate of decomposition is low up to a reaction fraction of 0.1 beyond which the decomposition is rapid as shown in Figure 15.17. The gaseous decomposition products are mainly methane (mass 16), propylene (mass 42) and butylene (mass 56) with minor quantity of ethylene (mass 28). Formation of methane is high when compared to other products, propylene and butylene. 

The formation of larger amounts of propylene in the case of decomposition of sodirnn M-propoxide and methane in the case of decomposition of iso-propoxide could be due to the normal chain and branched chain of alkyl group attached to -ONa in these com-poimds. Decomposition of sodium iso-propoxide follows the pattern similar to that of sodiiun ethoxide, where methane is found to be the major decomposition product. The weight loss observed for sodium iso-propoxide is 24 wt. %. 

Figure 15.24 Plot of sodium iso-propoxide decomposition at different linear heating rate (a) TG trace and (b) fraction decomposed deduced from above data.

Figure 15.26 Plot of In (g(a)/T2) vs 1000/T for (a) sodium n-propoxide decomposition and (b) sodium iso-propoxide decomposition derived from TGA data (non-isothermal run).

The activation energies for the decomposition of sodium n-propoxide and sodium iso-propoxide derived from the isothermal data are slightly higher than those of non-isothermal data. There could be two possible reasons (1) the temperature ranges of the isothermal and non-isothermal measurements are not the same and (2) the initial stage of decomposition under isothermal conditions includes a retardation period and also the specimen experiences a non-isothermal condition till the isothermal temperature is reached. Similar observations are reported in the literature [58,67]. 

Table 15.10 and A derived from MS data (non-isothermal runs) for sodium iso-propoxide... 

Figure 15.35 Plot of In [(3] vs 1/T for decomposition fraction (a = 0.1-0.9) of sodium iso propoxide under non-isothermal data.

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