Sodium arene derivatives

The tricyclic /3-aminocyclohexenone 234 was obtained via intramolecular photoarylation of the bromo arene derivative 233 (Scheme 40). Enamide 234 was treated with sodium hydride, followed by the mesylate derivative of [(trimethylsilyl)methyl]allyl alcohol, to give the allylated compound 235, which was converted to two allyliminium salts 236 and 237. However, attempts to photocyclize these compounds to tetracyclic derivatives were not successful, in contrast to the results of the earlier studies (Scheme 35) in which the spirocyclic system was easily generated in intermediates not rigidly tethered to the aromatic ring. 

Recently, Kobayashi noticed that the presence of a small amount of a surfactant such as sodium dodecyl sulfate (SDS) showed a remarkable enhancement of the reactivity in the Mukaiyama-catalyzed aldol reaction in pure water using Yb(OTf)3 or better Sc(OTf )3 as the catalyst without addition of the surfactant, the reaction was very sluggish (Scheme 8.4). Other surfactants such as calix[6]arene derivatives bearing sulfonate and alkyl groups or aromatic and aliphatic anionic surfactants have also been found to be highly effective in the aqueous Mukaiyama aldol reactions in pure water, affording the aldol products in high yields. This was probably due to the formation of micelles which stabilized the labile silyl enol ethers and thus promoted the aldol reaction. 

Thanks to the versatility of the Raman spectroscopy, nanoparticles AgNP(25) were used also to detect other policyclic aromatic pollutants (PAHs), like benzo [cjphenanthrene, triphenylene, and coronene [67]. In this case, selectivity is not as important as in other sensors, because the pollutant molecule can be in principle identified by its Raman spectrum. The affinity constants and the limits of detection of PAHs were also determined. In 2012, Coleman and co-workers developed a method to determine the critical micellar concentration (CMC) of cationic surfactants exploiting the SPB of a series of sulfonato calix [njarene-capped AgNPs [68]. The nanoparticles were synthesized by reducing AgNOs with sodium borohydride in aqueous solution in the presence of the sulfonate calix[n]arene derivatives 24, 26 and 27 (see Fig. 35.15) and characterized by TEM, DLS and UV-visible spectroscopy. Suspensions of the... 

Compared with the cone derivatives of calix[4]arene 4 [6], 2d shows a high affinity for potassium, as the cavity size of 2d is larger than that of calix[4]arene derivatives. This selectivity seems to be contradictory to the effect of sodium carbonate found in the selective preparation of 2d, but we presume this difference to be dependent on the coordination site. In the preparation of 2d, the sodium ion... 

In the case of 2d, the high affinities to alkali cations were observed in CD3OD and THF solution. In contrast to the cone conformer of calix[4]arene derivatives 4,2d prefers potassium ion to sodium ion. This difference of selectivity seems to be dependent on the size of cavity of host molecule. 

Previously, we have reported that the bulkier decyl ester type calix[4]arene derivative 6 [2] is available a sodium selective ionophore for polymeric membrane electrodes, independently of Diamond s work [3]. Selectivity coefficients for Na " with respect to other alkali and alkaline-earth metal ions, NH4, and H" " on the... 

Table V displays the sodium ion selectivity for three kinds of bridged type cal-ix[4]arene derivatives. Since the capping of the lower rim of calix[4]arene with a bridge of different length methylene groups results in the fixation of a rigid cone conformation and the change of the cavity size, the Na" " selectivity is expected to be improved.

In conclusion, the diester-diester mixed type derivative 7 and diester-bridged type 9 are promising neutral carriers for sodium ion assay. Further investigation on the electrode membrane condition such as membrane solvents and lipophilic salts for the calix[4]arene derivatives, 7-10, are currently being done in our laboratory-... 

Calixcrown compounds appear to be a new promising family of carriers for the selective removal of caesium from high salinity and acidity media such as MLW through an SLM. By choosing a highly hydrophobic organic diluent, o-NPOE, and a lipophilic crown-6-calix[4]arene derivative in the 1,3-altemate conformation suitable for caesium complexation over that of sodium, very selective and stable SLMs can be obtained (over a period of 50 days). 

The reaction of (dibromomethyl)arenes with sodium acetate and calcium carbonate under liquid liquid conditions yields not the bisacetoxy derivative but the aldehyde in high yield (65-82%) [29,30]. 

Most of the studies carried out on cesium extraction conclude that the most efficient crown ethers for extraction of this cation are benzo-21-crown-7 derivatives. Like dicarbollides, these compounds need a synergistic agent or polar diluent modifier to allow cesium to be extracted from very acidic solutions. The resulting selectivity for cesium over sodium is low. Only dialkoxy-calix[4]arene-crown-6 and calix[4]arene bis(crown-6) compounds allow objectives to be fulfilled extraction of cesium at low-level concentration from acidic media.19... 

The significant selectivity for cesium over rubidium (,S Cs/Rb = 39), compared with that obtained for the calix[4]arene-crown-6 derivatives (8 for MC8 and less than 5 for MC14), has to be pointed out. Replacement of 0.1 M of sodium hydroxide by potassium hydroxide strongly decreases the cesium distribution ratios for calix[4] arenes-crown-6 (DCs < 1). On the contrary, they are slightly increased for tBuC[4], leading to a cesium-over-rubidium selectivity exceeding 150. This selectivity value... 

In conclusion, calix[4]arene-bis(crown-6) and dialkoxy calix[4]arene crown-6, and especially their dibenzo derivatives, which display an important hydrophobic-ity, seem best suited for the extraction of cesium from very acidic media or media containing large amounts of sodium. In 2006, Mohapatra confirmed the high efficiency and selectivity of BC5 and BC10 for the extraction of cesium from simulated acidic high-activity level waste. The Cs distribution ratio follows the trend of diluent... 

Extraction of Cesium and Sodium—Cs/Na Selectivity—Competitive Extraction of Cesium in the Presence of an Excess of Sodium by Nitro Derivatives of Calix[4]arene-diisopropoxy-crown-6 and Calix[4]arene-bis-crown-6... 

Several classes of synthesized calixarenes bearing several moieties (ether, ester, and amide derivatives), were tested for the extraction of strontium picrates (from aqueous solutions into dichloromethane).128 Only a few of them show appreciable extraction levels. The p-i-butyl calix[6]arene hexa(di-/V-ethyl)amide (CA4) shows a very high extraction level of alkaline earth cations with respect to alkali metal cations. Moreover, dealkylation of the calix[6]arene hcxa(di-/V-cthyl)amidc (CA5) decreases the extraction of both sodium and strontium. As this decrease is much more important for sodium than for strontium, the Sr/Na selectivity, which increases from 3.12 to 9.4, is better than that achieved for DC18 derivative under the same conditions (8.7). These results were confirmed by extraction of strontium (5 x 10 4 M) from 1 M HN03 solutions, where it was found that p-t-butyl calix[4]arene tetra(di-N-ethyl) amide (CA2) (10 2 M in NPOE) extracts only sodium (DNa = 12.3, DSl < 0.001). 

As hosts for cations, the phenolic oxygen atoms at the calixarene lower rim (Figure 3.81) have the potential to act in a similar way to the anisole residues of the spherands, either in the original hydroxyl form or as alkyl ether derivatives. This kind of behaviour has been observed for the methyl ether of the parent /j-f-butylcalix[4] arene (compound 3.121) upon reaction with a mixture of sodium benzoate, one... 

Mesitylene and hexamethylbenzene cyclohexadienyl ruthenium complexes 236 have also been prepared in good yield by reduction of their corresponding bisarene ruthenium dications 235 with sodium borohydride in water (142,143). Cyclohexadienyl derivative 236c can be easily formed by treatment of bisarene ruthenium(O) complex 197 (arene = hexamethylbenzene) with a solution of hydrochloric acid in acetone. The structure of 236c and the presence of the endo C—H bond have been clearly resolved by infrared and 1H-NMR spectra (144,145) [Eq. (28)]. 

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