Isopropanol as solvent

The aldehyde or ketone, when treated with aluminum triisopropoxide in isopropanol as solvent, reacts via a six-membered cyclic transition state 4. The aluminum center of the Lewis-acidic reagent coordinates to the carbonyl oxygen, enhancing the polar character of the carbonyl group, and thus facilitating the hydride transfer from the isopropyl group to the carbonyl carbon center. The intermediate mixed aluminum alkoxide 5 presumably reacts with the solvent isopropanol to yield the product alcohol 3 and regenerated aluminum triisopropoxide 2 the latter thus acts as a catalyst in the overall process ... 

When benzophenone is photoreduced in isopropanol as solvent, benz-pinacol and acetone are produced ... 

The use of ethanol or isopropanol as solvent results in the formation of tris (a-ethoxybenzyl)- or tris(a-isopropoxybenzyl)-phosphine, respectively, in yields of up to 85% ... 

Coteiro s group studied the influence of the solvent to the ternary oxide, Ru-Ti-Sn, electrode stability (Coteiro et al. 2006). The precursor mixtures were prepared by dissolving RuCh H20, TiCl4, and SnCl2 2H20 salts into the solvent. Two different solvents, HC1/H20 (1 1 v/v) or isopropanol, were applied. The results with isopropanol as solvent showed that tin loss can be eliminated and higher elec-trochemically active area and stability can be achieved, when compared with HC1 solution. 

Since the initiation by y-irradiation is unsatisfactory for AAm-TAA system, the suspension polymerization procedure is adopted using isopropanol as solvent and AIBN as initiator to obtain a resin having a capacity of 0.63 meq/g. When vinylacetate (26 % by weight based on AAm) is used as a third monomer, the capacity is improved from 0.63 to 0.9 meq/g. For the MAAm-TAA system the chemical initiation is not preferred since the yields of the resins obtained by this method are lower than those obtained by y-irradiation. 

We carried out studies using technical-grade isopropanol as solvent with excellent results. Illustrated in Table 14.1 is the coupling of a series of aryl bromides and chlorides with a variety of arylboronic acids at low catalyst loadings. Aryl chlorides are very attractive substrates as they... 

Firstly, the /-piperitone is reduced, by means of a reagent such as lithium aluminium hydride to a mixture of diastereomeric alcohols, l-cis-piperitol (36%) and df-frans-piperitol (64%). This mixture is reduced by a Raney nickel catalyst modified by addition of nickel (II) chloride. The hydrogenation is carried out in isopropanol as solvent at 25 °C and a hydrogen pressure of 60 psig. During hydrogenation, the stereochemistry of the isopropyl group controls the stereochemistry of the other centres. 

The most efficient of these Pd/NHC systems reported to date for the synthesis of di- and trisubstituted biaryls is based on an NHC-modified pal-ladacycle, NaO Bu as base, and isopropanol as solvent [47]. Using this protocol, sterically hindered aryl chlorides couple with sterically hindered boronic acids at room temperature in minutes. The proposed activation of the catalyst relies on the formation of an unstable palladium hydride upon attack of TrO followed by P-hydrogen elimination (Scheme 10). 

Fig. 9.8 Selectivities for Rh-Ce/Si02 (a) and Rh-Ge/Al203 (b) catalysts prepared by surface redox reaction at 50% citral conversion (T,e,cion=70°C, PH2=76bar, isopropanol as solvent) ( ) citronellal (a) unsaturated alcohols ( ) citronellol. Reprinted from G. Lafaye, C. Micheaud-Especel, C. Montassier, P. Marecot, Appl. Catal. A, 2002, 230,19-30, Copyright (2002), with permission from Elsevier.

Although the photoinitiator is readily soluble in the monomer(s), it is insoluble in the polymer. Thus, Lucirin TPO precipitates and forms an amorphous core surrounded by a polymeric shell. The encapsulation efficiency, which is the ratio of encapsulated material to material initially added to the system, was determined to be about 90%. The release of the initiator into the environment was investigated using isopropanol as solvent. Compared to a 50% release of Lucirin TPO after less than 1 min, the release from a crosslinked shell is significantly prolonged to about 5 min. 

Toluidinylnaphthalene-6-sulfonic acid [7724-15-4] M 313.9, pKj st Crystalhse the acid twice from 2% aqueous KOH and dry it imder high vacuum for 4 hours at room temperature. It also ciystalhses from H2O. It is tested for purity by TLC on sihea gel with isopropanol as solvent. The free acid is obtained by acidifying a saturated aqueous solution. [Beilstein 14 H 762.]... 

The use of cerium on Ru-based catalysts supported on alumina and activated carbon increased selectivity to unsaturated alcohols in the hydrogenation of crotonaldehyde (in the gas phase) and citral (in the liquid phase with isopropanol as solvent). However, the observed activities were very low. 

Figure 6.4 Schematic Representation of the Formation of Highly Distorted Nanoscopic Aluminum Fluoride by Reacting Aluminum Isopropoxide with Anhydrous Hydrogen Fluoride in Isopropanol as Solvent. Reproduced from Ref. [26] with permission of Royal Society of Chemistry.

Figure 2.2 Effect of the R = [HF]/[Al] molar ratio on the X-ray diffraction powder pattern. For each X-ray diagram, the R molar ratio is noticed as well as the stabilized phase. Syntheses were conducted at T = 160°C, t— 2h using Al(N03)3.9 Fl20 and water/isopropanol as solvents...

The effect of the nature of the synthesis medium has also been considered through the replacement of both titanium precursor and solvent. An organic medium has therefore been used containing titanium isopropoxide as precursor and isopropanol as solvent. In these conditions, two different R = [HF]/[Ti] molar ratios have been studied, i.e. 3 and 4. The corresponding X-ray diffraction powder patterns (not shown) are similar to those obtained from the aqueous medium with a broadening of the X-ray peaks suggesting smaller particle size. Here, the salient point is that the recovered powders are coloured, which is consistent with mixed-valency Ti. Such a point will be discussed later. 

Figure 8.19 UV-Visible spectra of Ti hydroxyfluorides prepared by microwave assisted synthesis using either water, R=HF/Ti = 3, Ti oxychloride as precursor (red curve), or isopropanol as solvent, TI Isopropoxide as precursor, R—3 (green curve), or isopropanol as solvent, Ti isopropoxide as precursor, R = 4 (blue curve). Reproduced with the permission of ACS or American Chemical Society...

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