Methylene complex with water

Reactions leading to surface-active diamides form emulsions of the hydrated [A1(H20)6]C13 complex. However, by hydrolysis of the RPOCl2-AlCl3 complex with water at a molecular ratio of 1 6-7.5 in methylene chloride at a temperature of -10°C, the A1C13 from the complex reacts selectively forming a precipitation of [A1(H20)6]C13, which can be easily filtered off. From the solvent the alkanephosphonic acid dichloride can be isolated in good quality (Table 4). 

Aluminum chloride dissolves readily in chlorinated solvents such as chloroform, methylene chloride, and carbon tetrachloride. In polar aprotic solvents, such as acetonitrile, ethyl ether, anisole, nitromethane, and nitrobenzene, it dissolves forming a complex with the solvent. The catalytic activity of aluminum chloride is moderated by these complexes. Anhydrous aluminum chloride reacts vigorously with most protic solvents, such as water and alcohols. The ability to catalyze alkylation reactions is lost by complexing aluminum chloride with these protic solvents. However, small amounts of these "procatalysts" can promote the formation of catalyticaHy active aluminum chloride complexes. 

According to a detailed mechanistic study, the first step is the abstraction of the relatively acidic hydrazone proton (93- 97). This is followed by hydride attack on the trigonal carbon of the C=N bond, mainly from the a-side at C-3, together with the concomitant loss of the tosylate anion (97 -> 98). Expulsion of nitrogen from the resulting intermediate (98) yields a fairly insoluble anion-metal complex (99) which upon decomposition with water provides the methylene derivative (100). 

Methoxyestra-l,3,5(10),14-tetraen-17-one. A solution of 9.3 g (0.0328 mole) of 3-methoxyestra-l,3,5(10),14-tetraen-17)S-ol in 300 ml of methylene dichloride is added at a rapid dropwise rate to a stirred suspension of 46.5 g (0.18 mole) of the dipyridine-chromium VI complex in 800 ml of methylene dichloride at room temperature. The mixture is stirred 45 min and then filtered. The residue is washed with ethyl acetate and the organic layers are combined. Water is added to the filtrates and sufficient ethyl acetate is added to make the organic layer less dense than water. After the organic layer is washed with water it is dried over sodium sulfate and concentrated to leave... 

The method developed by Epton [212,213] became the universally accepted method for the analysis of active matter of anionic and cationic surfactants. Epton s method, also known as the two-phase titration, is based on the titration of the anionic surfactant with cetylpyridinium bromide, a cationic surfactant, in the presence of methylene blue as indicator. A solution of the anionic surfactant is mixed with the indicator dissolved in dilute sulfuric acid, followed by further addition of chloroform, and then it is titrated with the cationic surfactant. Methylene blue forms a complex with the anionic salt that is soluble in chloroform, giving the layer a blue color. As the titration proceeds there is a slow transference of color to the water layer until the equivalence point. At the equivalence point colors of the chloroform and water layers are visually the same. On successive additions of titrant the chloroform layer lightens in shade and finally becomes colorless. 

Fig. 3. Stereoview of the inclusion complex between a hydrogen-bonded dimer of host 3 with water and methylene chloride as guests. The crystal structure of this compound contains two additional species, a disordered CH Clj and fractional water (donated by S ). Both lie outside the complex between the bound water and an adjacent host unit (taken from Ref.28>)...

The linear telomerization reaction of dienes was one of the very first processes catalyzed by water soluble phosphine complexes in aqueous media [7,8]. The reaction itself is the dimerization of a diene coupled with a simultaneous nucleophilic addition of HX (water, alcohols, amines, carboxylic acids, active methylene compounds, etc.) (Scheme 7.3). It is catalyzed by nickel- and palladium complexes of which palladium catalysts are substantially more active. In organic solutions [Pd(OAc)2] + PPhs gives the simplest catalyst combination and Ni/IPPTS and Pd/TPPTS were suggested for mnning the telomerizations in aqueous/organic biphasic systems [7]. An aqueous solvent would seem a straightforward choice for telomerization of dienes with water (the so-called hydrodimerization). In fact, the possibility of separation of the products and the catalyst without a need for distillation is a more important reason in this case, too. 

In this method, first established by Herz and later studied by Hale, hexamine is introduced into fuming nitric acid which has been freed from nitrous acid. The reaction is conducted at 20-30 °C and on completion the reaction mixture is drowned in cold water and the RDX precipitates. The process is, however, very inefficient with some of the methylene and nitrogen groups of the hexamine not used in the formation of RDX. The process of nitrolysis is complex with formaldehyde and some other fragments formed during the reaction undergoing oxidation in the presence of nitric acid. These side-reactions mean that up to eight times the theoretical amount of nitric acid is needed for optimum yields to be attained. 

Water is a possible axial ligand for the transient Ni(PP) in these systems and has been shown to form weak complexes with other nickel porphyrin species (18). While we cannot unequivocally rule out weak, transient ligation, the observation of similar transient behavior in Ni(OEP) and Ni(PPDME) in noncoordinating, nonaqueous, solvents (toluene, methylene chloride (9, unpublished results)) leads us to conclude that the transient behavior of the Ni(PP) in acetone/water is not predicated upon ligand binding. 

Attempts have been made to mimic proposed steps in catalysis at a platinum metal surface using well-characterized binuclear platinum complexes. A series of such complexes, stabilized by bridging bis(diphenyl-phosphino)methane ligands, has been prepared and structurally characterized. Included are diplati-num(I) complexes with Pt-Pt bonds, complexes with bridging hydride, carbonyl or methylene groups, and binuclear methylplatinum complexes. Reactions of these complexes have been studied and new binuclear oxidative addition and reductive elimination reactions, and a new catalyst for the water gas shift reaction have been discovered. 

Due to the possibility of chain initiation by direct reaction of a metal-dioxygen complex with substrate, many of these complexes have been examined as autoxi-dation catalysts, particularly for the oxidation of olefins.136 139-141 172-179 Thus, Collman et al.172 reported that dioxygen complexes of Ir(I), Rh(I), and Pt(0) catalyzed the autoxidation of cyclohexene at 25° to 60°C in benzene or methylene chloride. Cyclohexene-3-one is the major product (together with water) and cyclohexene oxide a minor product ... 

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