Moisture tolerance

Keywords Bismuth(IH) salts Catalysis Green chemistry Lewis acidity Moisture tolerance Non-toxicity Organic transformations... 

Yamamoto had earlier reported that Lewis acid activation of valine-derived oxazaborolidine 60 yielded a highly reactive and moisture-tolerant LLA catalyst 61 for the Diels-Alder reaction (Scheme 5.76) [145]. In later studies, activation of 60 with the super Bronsted acid, C,sF5CHTf2, was found to produce the even more reactive catalytic species BLA 62. During studies toward an enantioselective route to Platensimycin [146], BLA 62 was found to catalyze the Diels-Alder reaction between various monosubstituted dienes and ethyl acrylate to afford adducts... 

In an effort to develop new chiral BINOL-Ti complexes, chemical modifications of the chiral complex (f )-BINOL-Ti(OPr )2 (R-2) that can easily be prepared by simply mixing ( PrO)4Ti and (/ )-BINOL in the absence ofMS4A have been studied [37c-e]. A dimeric form has been reported for the single-crystal X-ray structure of complex R-2 [38], (I )-BINOL-Ti-p3-oxo complex, prepared via hydrolysis of complex R-2 has been shown to serve as an efficient and moisture-tolerable asymmetric catalyst [37d,e]. It is noteworthy that the (/ )-BINOL-Ti-)i3-oxo catalyst [37e] shows a remarkable level of (+)-NLE (asymmetric amplification), thereby attaining the maximum enantioselectivity for this system by using (/ )-BINOL with only 55-60% ee as the chiral source (consult Scheme 8C. 14). 

A highly enantioselective direct Mannich reaction of simple /V-Boc-aryl and alkyl- imines with malonates and /1-kclo esters has been reported.27 Catalysed by cinchona alkaloids with a pendant urea moiety, bifunctional catalysis is achieved, with the urea providing cooperative hydrogen bonding, and the alkaloid giving chiral induction. With yields and ees up to 99% in dichloromethane (DCM) solvent, the mild air- and moisture-tolerant method opens up a convenient route to jV-Boc-amino acids. 

Chiral BINOL-indium(ni) complexes have been employed in several enantioselective allylations (i) in the ionic liquid, hexylmethylimidazolium-PF6, for aldehydes,190 (ii) a moisture tolerant version, for a wide variety of aldehyde types,191 and (iii) a recyclable example, useful for aromatic, aliphatic, and a,/S-unsaturated ketones.192... 

Recently Toste et al. [6] introduced the air- and moisture-tolerant Re-complex (dppm)Re(0)Cl3 as an alternative. Applied as catalyst in 5% amounts (5h at 65 °C) the propargylation of 1,2,3-trimethoxybenzene (9) with model reactant 15 is achieved with 92 % yield of the corresponding mono-substitution product. The potential of this method is highlighted by the successful synthesis of natural products such as /l-apopicropodophyllin (24) (Scheme 5). 

Epoxy crack injection systems are unfilled compositions, based on low-viscosity liquid epoxy resins and low-viscosity moisture-tolerant hardeners. The low viscosity of the system aids penetration into fine cracks and achieves the right balance of gel time (Anchor Chemicals/Air Products, undated a). Cracks as narrow as 0.05 mm can be filled with epoxy injection systems (CCA/, 1985). 

It is apparent that water consumed through urea formation is minor under typical industrial conditions. So again, the good moisture tolerance of pMDI reflects that the binder is not water miscible. 

The moisture tolerance of pMDI is utilized in steam injection pressing (SIP), where steam is injected into the flake or strand mat (through the press platens) immediately prior to, and during compaction. SIP accelerates heat transfer and hotpress production, especially for very thick products such as laminated strand lumber. Besides accelerated production, steam processing increases the dimensional stability of the resulting composite [45,46]. Isocyanate resins appear to be the only exterior grade wood binders which can withstand the moisture extremes found in SIP [33,34,47]. 

P. Subramaniam, S. Jayasurya, K.L. GirishBabu, Evaluation of glass carbomer sealant and a moisture tolerant resin sealant - a comparative study, InL J. Dent. Sci. Res. 2 (2015) 42-48. 

CAS 2210-79-9 EINECS/ELINCS 21 4 3 Uses Reactive epoxy diluent for tooling, elec, applies., coatings, flooring Features Good chem. resist., esp. against adds and soivs., low volatility, moisture tolerant... 

Several other methods have been developed, including small-pile storage tests and drillabflity tests, to evaluate the degree of moisture tolerance of fertilizers. All of these tests have some merit and can-be found in the literature [1,2,3,8 65,66,67,68,69.701. 

Firouzabadi, H., Iranpoor, N., Jafarpour, M. and Ghaderi, A. 2006a. Zr0Cl2-8H20 as a highly efficient and the moisture tolerant Lewis acid catalyst for Michael addition of amines and indoles to a, 3-unsaturated ketones under solvent-free conditions. J. Mol. Catal. A Chem. 252 150-155. 

While the formation of a variety of carbon stereocentres has been effectively achieved, stereoselective approaches for the preparation of P-stereogenic phosphines have, until recently, been non-existent. In this context, Bergman s group has developed several chiral ruthenium catalysts to be investigated for the enantioselective ruthenium-catalysed alkylation of secondary phosphines into the corresponding chiral air- and moisture-tolerant tertiary phosphine-borane products after a subsequent treatment with BHs.THF. " These reactions proceeded through the intermediacy of nucleophilic phosphido species, which had low barriers to pyramidal inversion, allowing a DKR process. 

The hydrogenation of a series of a, -unsaturated ketones by H2 in EtOH is catalysed by air and moisture tolerant [Ru(cymene) Cl2]2 in the presence of [(5,5)-Phos-Biox] (59) and LiOH to form corresponding allylic alcohols in yields up to 98% and up to... 

Reduction of primary, secondary, and tertiary amides to the corresponding amines in toluene and in the presence of PhSiH3 occurs with good functional-group tolerance in the absence of any metal using air- and moisture-tolerant boronic acid as the catalyst. ... 

Futatsugi K, Yamamoto H (2005) Oxazaborolidine-derived Lewis acid assisted Lewis acid as a moisture-tolerant catalyst for enantioselective Diels-Alder reactions. Angew Chem Int Ed Engl 44 1484-1487... 

---