On the thermochemistry of intercalation of n-alkylamines into α-titanium hydrogenphosphate

Lamellar-titanium hydrogenphosphate (-TiP) suspended in water or 1,2-dichloroethane (dce) intercalates 7.70 meq g¹ ofn-alkylamines (C₁-C₄), as determined by potentiometry and thermogravimetry. The thermal decomposition of the intercalates takes place in three stages: dehydration, removal of amines, and condensation of the hydrogenphosphate to pyrophosphate. The increase in the-TiP interlayer distance (7.56×10² pm) during the intercalation was followed by x-ray powder diffraction. The standard enthalpy (rH _m ^o ) involved in the overall reaction O₃PO-H + RNH₂ O₃P-O^{– +}H₃NR, which was determined by reaction-dissolution calorimetry, correlates linearly with the number of carbons in the alkyl chain and with the interlamellar distance. An intercalation mechanism is proposed, starting from the amine protonation by POH groups and its insertion between the sheets. An increase in enthalpy of –2.67 and +2.56 kJ mol^–1 or –1.24 and +1.20 kJ mol^–1/10² pm for each CH₂ group of then-alkyl chain in dce and water, respectively, for this series of amines is proposed.     

Multiple-step preparation and physicochemical characterization of crystalline α-germanium hydrogenphosphate

The reaction between germanium oxide and phosphoric acid has previously been described and led to impure germanium hydrogenphosphate samples with low crystallinity. A new multiple-step route involving the same reaction under refluxing and soft hydrothermal conditions is described for the preparation of pure and crystalline α-GeP. The physicochemical characterization of the samples allows accompaniment of the reaction evolution as well as determining short- and long-range structural organization. The phase purity of the α-GeP sample was confirmed by applying Rietveld's profile analysis, which also determined the cell parameters of its crystals.     

Ring opening of fluoroalkyl-containing α,β-epoxyketones by aromatic amines

Aromatic amines cause ,-epoxyketones containing a -fluoroalkyl group to undergo ring opening at the -position to give -amino--hydroxyketones.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 882–883, May, 1994.     

Palladium-catalyzed α-regioselective allylic amination of Morita-Baylis-Hillman acetates with simple aromatic amines

An efficient allylic amination of Morita-Baylis-Hillman acetates with simple aromatic amines provided good yields with excellent α-regioselectivity (up to exclusive α-product) under the catalysis of Pd(2)(dba)(3)/ferrocene-type diphosphine ligand.     

Intercalation ofn-alkylamines into α-titanium phosphate from aqueous solutions

The intercalation reactions betweenn-alkylamines and -titanium phosphate in aqueous media have been investigated. The compounds with the maximum intercalation have the formula -Ti(HOPO₃)₂ · 2 C _n H _2n+1 NH₂ · H₂O (n=1–10). Defined crystalline phases with lower amine content are described, the general formula being -Ti(HOPO₃)₂ · _m C _n H _2n+1 NH₂ ·pH₂O (m=1.0 1.3, 1.5, 1.7). Whenm=1.0 then-alkylamines form a monomolecular layer. Whenm>1.0 the layer is bimolecular. The inclination angle and the packing density of then-alkylamines in the interlayer space is determined.     

Mechanism of dehydrogenation of cyclohexane on the crystalline α-oxide of chromium

Russian Chemical Bulletin - Dehydrogenation of cyclohexane on crystalline α-Cr2O3 proceeds according to a sextet-type mechanism. This conclusion agrees with the structural principles of...     

The oxidation of aromatic amines in the presence of “electron-rich” aromatic systems

The oxidation of aromatic amines to the corresponding nitro substituents is performed under mild, nonacidic conditions in the presence of highly nucleophilic aromatic systems such as indoles and furans.     

Synthesis of α-monoglycerides of aromatic acids

The synthesis of -monoglycerides of aromatic acids has been performed by the transesterification of the methyl esters of the corresponding acids with glycerol. The structures of the compounds obtained have been confirmed by their IR, UV, and¹H and¹³C NMR spectra.A. B. Bekturov Institute of Chemical Sciences, Academy of Sciences of the Republic of Kazakhstan, Almaty, fax (3272) 61 57 65. Translated from Khimiya Prirodnykh Soedineii, No. 4, pp. 452–457, July–August, 1999.     

Study on the Intercalation of TMAPP into α-ZrP

In this paper, an intercalation compound of layered α-ZrP with TMAPP was firstlysy nthesized by using the α-ZrP-BA pre-intercalation compound as intermediate. And wesystemically investigated the intercalation behavior of TMAPP into α-ZrP by XRD, visible spectrum and fluorescence spectrum.     

Tropylium ion mediated α-cyanation of amines

Tropylium ion mediated α-cyanation of amines is described. Even in the presence of KCN, tropylium ion is capable of oxidizing various amine substrates, and the resulting iminium ions undergo salt metathesis with cyanide ion to produce aminonitriles. The byproducts of this transformation are simply cycloheptatriene, a volatile hydrocarbon, and water-soluble potassium tetrafluoroborate. Thirteen total substrates are shown for the α-cyanation procedure, including a gram scale synthesis of 17β-cyanosparteine. In addition, a tropylium ion mediated oxidative aza-Cope rearrangement is demonstrated.     

Silver-mediated aminophosphinoylation of propargyl alcohols with aromatic amines and H-phosphine oxides leading to α-aminophosphine oxides

A new silver mediated aminophosphinoylation of propargyl alcohols with aromatic amines and Hphosphine oxides for the construction of a-aminophosphine oxides has been developed.The C-N and C-P bond could be efficiently formed in one pot operation via sequential C-C and C-O bond cleavage of propargylic alcohols.This present methodology,which not only provides a simple and alternative strategy for the synthesis of α-aminophosphine oxides,but also opens a new window for the cleavage reactions of propargyl alcohols via dealkynalation coupling.     

Concise synthesis of aromatic tertiary amines via a double Petasis–borono Mannich reaction of aromatic amines,formaldehyde, and organoboronic acids

A simple and efficient strategy to construct aromatic tertiary amines via a double Petasis–borono Mannich reaction of aromatic amines, formaldehyde, and organoboronic acids has been developed. The transformation provides a useful method for the synthesis of amine derivatives.     

Microwave-assisted synthesis of α-hydroxy aromatic ketones from α-bromo aromatic ketones in water

A reaction ofα-bromo aromatic ketones in water with microwave irradiation gave the correspondingα-hydroxy aromatic ketones in good yields.The use of microwaves was found to significantly improve yields and shorten the reaction time.This reaction afforded a very clean,convenient method for the synthesis ofα-hydroxy aromatic ketones.     

Direct synthesis of α-thio aromatic acids from aromatic amino acids

Modified amino acids are useful synthetic components in both chemistry and biology. Here we describe a simple, scalable two-step procedure to generate α-thio aromatic acids from aromatic amino acids with yields of up to 96%. Diazotization and α-lactone mediated bromination efficiently form the α-bromo acid with retention of configuration. Thiol substitution with mild reagents such as sodium hydrosulfide or sodium trithiocarbonate provides the inverted, free α-thio acid. The mildly acidic soft nucleophile can then be utilized in many synthetic applications.     

Facile synthesis of 2-nitromethyl aromatic ketones by insertion of benzynes into the C-C bond of α-nitroketones

A facile method to synthesize 2-nitromethyl aromatic ketones was developed. In the method, benzyne was generated in situ for the insertion to α-Nitroketones in one pot to achieve 2-nitromethyl aromatic ketones under mild conditions. Aromatic and aliphatic α-nitroketones were applied in the reaction, and the results show that aliphatic α-nitroketones gave excellent yields (up to 96%), while aromatic α-nitroketones gave moderate yields. The synthesized 2-nitromethyl aromatic ketones could be potential substrates to synthesize isoindoles.     

Direct and stepwise intercalation of alkylalcohols intoα-zirconium phosphate

Intercalation of alkylalcohols into -zirconium phosphate was investigated at 25°C and/or under reflux.n-Alcohols having two to five carbons and 2-propanol were taken up at 25°C. These alcohols, andn-hexanol and heptanol, also intercalated under reflux.n-Alcohols having eight to eighteen carbon atoms intercalated when a stepwise method was employed. 2-Butanol and tertiary amylalcohols intercalated under reflux using a butanol intercalate as a starting material. Ethanol-to-butanol intercalates were unstable at room temperature, losing alcohols and changing to -zirconium phosphate. The particle size of the -zirconium phosphate did not affect the intercalation of alcohols.     

Gold-complexes catalyzed oxidative α-cyanation of tertiary amines

Oxidative α-cyanation of tertiary amines is catalyzed by gold complexes with trimethylsilyl cyanide to afford the corresponding α-aminonitriles in the presence of tert-butyl hydroperoxide in good to excellent yields under acid-free conditions at room temperature.     

One-pot asymmetric synthesis of α-trifluoromethylated amines from α-trifluoromethyl ketones

Diastereoselective reduction of (Rs)-N-tert-butanesulfinyl α-trifluoromethyl ketimines formed in situ from the corresponding α-trifluoromethyl ketones and N-tert-butanesulfinamide has been achieved, and either diastereomer of N-tert-butanesulfinyl α-trifluoromethyl amines was obtained in good yields with excellent diastereoselectivities (up to 99:1 dr) using NaBH₄ and L-Selectride as the reductants, respectively.