Isopropoxy group

Chemical properties of isopropyl alcohol are determined by its functional hydroxyl group in the secondary position. Except for the production of acetone, most isopropyl alcohol chemistry involves the introduction of the isopropyl or isopropoxy group into other organic molecules by the breaking of the C—OH or the O—H bond in the isopropyl alcohol molecule. 

Quinoxalinyl, 4-cinnolinyl, and 1-phthalazinyl derivatives, which are all activated by a combination of induction and resonance, have very similar kinetic characteristics (Table XV, p. 352) in ethoxylation and piperidination, but 2-chloroquinoxaline is stated (no data) to be more slowly phenoxylated. In nucleophilic substitution of methoxy groups with ethoxy or isopropoxy groups, the quinoxaline compound is less reactive than the cinnoline and phthalazine derivatives and more reactive than the quinoline and isoquinoline analogs. 2-Chloroquinoxaline is more reactive than its monocyclic analog, 2-chloropyrazine, with thiourea or with piperidine (Scheme VI, p. 350). 

Chymotrypsin, in addition to its proteolytic activity, can also function as an esterase.1 It is inactivated by D.F.P., etc. (p. 186). The esterases firmly bind the phosphorus of D.F.P., and in the case of chymotrypsin the reaction is bimolecular, yielding a crystalline derivative containing two isopropoxy groups and one atom of phosphorus per protein molecule, but no fluorine.2... 

In a very similar way, hydroxy functionalized ATRP initiators such as 2,2,2-tribromoethanol can be used for the simultaneous polymerization of eCL and MMA (Scheme 25) [83]. Purposely, the ROP of eCL is promoted by Al(OfPr)3 added in catalytic amount so that the rapid alcohol-alkoxide exchange reaction (see Sect. 2.4) activates all the hydroxyl functions. In order to avoid initiation by the isopropoxy groups of Al(0/Pr)3. The in-situ formed zPrOH is removed by distillation of the zPrOH/toluene azeotrope. On the other hand, the ATRP of MMA is catalyzed by NiBr2(PPh3)3. The two aforementioned one-step methods provide block copolymers with controlled composition and molecular weights, but with a slightly broad MWD (PDI=1.5-2). 

Wulff et al. recently reported another unique example of this inverse transformation [35]. Thus, treatment of a, P-unsaturated Fischer carbene complexes 138 with an isopropoxy group on the carbene carbon with ketene acetal 139 at 80 °C in THF under CO pressure gave 4-pentynoate derivatives 140 in good yield. The reaction was proposed to proceed through 1,4-addition of ketene acetal to the carbene complex to give a zwitterionic intermediate 141. This underwent internal... 

Pal and Kapoor74 have studied the reactions of isopropoxides of aluminum, titanium and zirconium with benzo- and phenylaceto-hydroxamic adds in anhydrous benzene. Solid products of the types Al(OPr )3 L and M(OPri)4 L (where M = Ti or Zr and L is the hydroxamic acid) have been isolated all the aluminum and zirconium products are white in colour whereas titanium ones are yellow. The mixed isopropoxide hydroxamates interchange their isopropoxy group with r-but-oxy groups, yielding r-butoxide products. 

The Cadarache group39 focused its modeling contribution on di(isopropoxy)-calix[4]arene-crown-6. It was deduced from these simulations that the 1,3-alternate conformation is much more preorganized than the cone conformation to bind a large cation in water and in vacuo. It can be explained by the fact that the isopropoxy groups, which are near to the crown basis, can prevent the complexation of small cations by shielding the complexation site constituted by the four phenoxy oxygen atoms. 

Figure 19.9. Structure of colchicine. The biophore A (bold, see Fig. 19.8) is responsible for the therapeutic effectiveness. Toxicophore B (see Fig. 19.10 shown in bold) is responsible for the induction of sister chromatid exchanges (SCE) in vivo. Removal of toxicophore B or its replacement be isopropoxy groups abolishes the induction of SCEs without affecting the therapeutic potential.

In mixed acetals the identities of the carbon-alkoxy bond cleaved or retained are a synthetically important issue. Equations (58) [177,178] and (59) [179] illustrate discrimination between oxy groups. In the former the isopropoxy group more accessible to the Lewis acid seems to be eliminated whereas in the latter reaction, a better leaving group, the hydrogen peroxide anion, is eliminated and, at the same time, the more cation-stabilizing methoxy group remains in the product. 

The bulk of the isopropoxy groups on the vinyl and methacryl silanes is unique among silane monomers in that, through their enhanced stability, levels of incorporation of silane an order of magnitude greater than standard methoxy-substituted monomers is possible. Thus, much higher performance can be achieved using these silane monomers. 

Reactivation of alkylphosphorylated acetylcholinesterase. Spontaneous reactivation (dashed arrow) by water occurs at an insignificant rate however, loss of one isopropoxy group occurs at a much more rapid rate, yielding the aged enzyme, which is resistant to reactivation. The regeneration of the enzyme by pralidoxime is shown at bottom. 

Sodium isopropoxide replaces the 2-bromo atom of 1-substituted 2,4,5-tribromoimidazole by an isopropoxy group <87JCS(P1)1437>. In 1,4-dinitroimidazole (81) reaction with methanol leads to c/ne -substitution, the reaction being first order with respect to both reactants and also to hydroxide ions. The yield is not affected by increasing the concentration of methanol from 10 to 40%, and only slightly by raising the pH from 8 to 10. Above that level the product is not formed (Equation (27)) <84PJC311>. 

This resin-bound substrate was then used for the synthesis of 1,4-quinone derivatives (Fig. 6.2). In the first step, the isopropoxy-group was displaced with primary amines (Fig. 

The synthesis of substituted squaric acid derivatives was shown in two other reactions. In one synthesis, the educt shown in Figure 6.2 was used the isopropoxy group was displaced with different secondary amines and the products were cleaved from the resin. 

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