Solventless, room temperature

Solventless, Room-Temperature Diels-Alder Reaction Intramolecular Nucleophilic Acyl Substitution A Huge Increase in Molecular Complexity in a 10-mL Beaker... 

Figure 1. Solventless, room temperature Diels-Alder reaction.

A.dhesives, Cjanoac late, Eapid Room Temperature Curing, Solventless, Army Materials and Mechanics Research Center, Watertown, Mass. 

Rhodium and iridium nanoparhcles entrapped in aluminum oxyhydroxide nanofibers were shown by Park et al. to be suitable catalysts for the hydrogenation of arenes and ketones at room temperature, with hydrogen at ambient pressure [103]. Rhodium in aluminum oxyhydroxide [Rh/A10(0H)] and iridium in aluminum oxyhydroxide [Ir/A10(0H)], were simply prepared from readily available reagents such as RhCls and IrCls hydrates, 2-butanol and Al(O-sec-Bu) at 100°C. Substrates such as cyclopentanone, 2-heptanone, ethyl pyruvate, acetone and 2,6-dimethyl-4-heptanone were reduced to the corresponding alcohols either in n-hexane at room temperature (maximum TOF 99 h" for ethyl pyruvate) or in solventless conditions at 75 °C using 4 atm of H2 (maximum TOF 660h" for acetone, 330 for 2-heptanone). 

A solventless PMR resin became known under the designation LARC 160 (15), which could be processed as a hot melt. An exchange of MDA in PMR-15 with a liquid isomeric mixture of di- and trifunctional amines (Jeffamine 22) provided a mixture of monomeric reactants which was tacky at room temperature. In the presence of 3% methanol the resin could be processed via a hot melt process. Unfortunately, the cured resin was inferior with respect to thermal oxidative stability in comparison to PMR-15. 

Studies on the immobilization of Pt-based hydrosilylation catalysts have resulted in the development of polymer-supported Pt catalysts that exhibit high hydrosilylation and low isomerization activity, high selectivity, and stability in solventless alkene hydrosilylation at room temperature.627 Results with Rh(I) and Pt(II) complexes supported on polyamides628 and Mn-based carbonyl complexes immobilized on aminated poly(siloxane) have also been published.629 A supported Pt-Pd bimetallic colloid containing Pd as the core metal with Pt on the surface showed a remarkable shift in activity in the hydrosilylation of 1-octene.630... 

This technique is, of course, only applicable to organic compounds in soil that are sufficiently volatile at room temperature or slightly above that they exist in the headspace above the samples. For such samples, the technique is elegant in that it is solventless, i.e., there is no solvent interference, is amenable to automation, and can be directly coupled to a gas chromatograph and/or alternate techniques such as mass spectrometry to ensure equivocal identification of the organics. 

Supramolecular self-assembly has been found to be dramatically accelerated in some cases, and this is perhaps the reason why solventless reactions have been rapidly adopted by coordination chemists. For example, the formation of a platinum-containing square is dramatically accelerated compared with the same reaction in water (Figure 2.3). In water, the reaction needed to be heated at 100 °C for 4 weeks. In a solvent free approach, approximately the same yield was achieved in 10 min at room temperature. Water and ethanol were the only solvents used in the work up of the reaction. This approach was then extended to bowl-shaped and helical supramolecular structures. 

The two components cure without evolution of any by-products, little or no volume change occurs and the system is ideally suited for use in thick and variable thickness bondlines. Solventless and 100% solid systems are possible which cure at room temperature within a few minutes. Viscosity, curing rate and cure temperature requirements can be tailored to meet the user s needs. Application of the system is generally made by two-part metering and mixing equipment. 

Direct addition of an alkylsulphonate into imidazole is useful, not only to synthesize the sulphonate anion, but also different anions via metathesis in the halogen free method. For example, the alkylation of /V-alkylimida/oles such as /V-mcthylimidazolc with alkylsulphonate can be performed under solventless conditions at room temperature affording, after 48-72 h, the corresponding 1,3-dialkylimidazolium alkanesulphonate salts as crystalline solids in almost quantitative yields (5) [48], The alkane sulphonate anions can easily be substituted by a series of other anions by metathesis ... 

Many of the above cited applications utilize solventless epoxy resins containing latent catalysts which are designed to be unreactive at room temperature but will give rapid cure of resin with the application of heat. 

There are two basic VPI resin formulations. One is based on epoxy resins, and the other is based on unsaturated polyesters. Both are typically one-part solventless compositions that are completely polymerizable. Volatile, nonpolymerizable solvents cannot be tolerated because these will lead to bubbling in the vacuum impregnation procedure. To control viscosity of the resin formulations, the epoxies contain low-viscosity, reactive diluents of the monoglycidyl ether type the unsaturated polyester formulations contain styrene or vinyltoluene as reactive diluents. Both resin types contain catalysts that become active only at elevated temperatures to insure long-term stability at room temperature. The epoxy resins are frequently catalyzed with metal organic compounds such as titanium complexes, and peroxides are usually the main catalyst in the unsaturated polyester formulations. In addition to the ingredients mentioned here, the compositions may contain additives such as cocatalysts, activators, and accelerators. However, there are no particular fillers used in VPI resins. 

Acylation of electron-rich arenes with AC, BC, and benzotrichloride can be performed in the presence of hydrated zirconia. The catalyst is prepared by treatment of an aqueous solution of zirconium(IV) oxychloride octahydrate (ZrOCl2 x 8H2O) with aqueous sodium hydroxide at room temperature, followed by heating the precipitate at 300°C for 5 h. The acetylation is performed in 1,2-dichloroethane at 60°C, whereas benzoylation is carried out under solventless conditions at 120°C (Table 4.16). It is remarkable that naphthalene is benzoylated selectively at the 1-position. The catalyst is recovered by filtration and reused three times with no loss of activity and selectivity in all cases. 

Can you see what happened there Ketone and amine react to give final freebase. Very nice. The authors even suggest that simpler matrices such as alumina or silica might work in place of clay. But, regardless, there is one small problem. The authors did not use any of the amines that an underground chemist would. As a solventless system, the authors had to use amines that were liquid or solid at or above room temperature. The lowest boiling amine they used was propylamine. And it was a borderline case causing them to use a modified pulse method so that it would not get too hot and escape the reaction matrix. 

The same methodology could be applied to platinum using Pt2(dba)3 and various room-temperature ionic liquids, and led to metallic Pt nanoparticles with a mean size near 2.0-2.5 nm (Scheme 6). " The isolated Pt(0) nanoparticles could be redispersed in the ionic liquid or in acetone or else used in solventless conditions for liquid-liquid biphasic,... 

Although the high solids, solventless and powder versions of epoxy coatings have created wider interest, it is possible with epoxies, as with most resin systems, to produce water-based versions. Usually the epoxy resin is emulsified with suitable surfactants. The co-reactive material can be, for example, a U/F resin emulsified with it to produce a stoving composition, or a water-soluble polyamine supplied in a second pack for room temperature cure. 

New developments of catalytic reactions with tin(iv) oxide are connected to the acid-catalysed biomass transformation. Acetalisation of glycerol with acetone in a 1/1 molar ratio was catalysed by tin(iv) oxide under solventless conditions at room temperature. The conversion could be greatly increased from 15 to 60% by the addition of 10 wt% of M0O3 (Scheme 21.6). It was further shown that molybdenum(vi) oxide led to a larger BET surface area... 

Adhesive acrylic monomer base, for acrylic plastics Adhesive, air-drying silicone rubber Adhesive, metallic structural honeycomb construction Adhesive, special rapid room-temperature curing, solventless... 

---