Tert-butylamine Research Articles

Nanostructured Pd/C catalysts prepared by grafting of model carboxylate complexes onto functionalized carbon

Pd(5 wt%)/C catalysts were prepared by grafting carboxylate precursors onto functionalized carbon. The functionalization of the support was carried out with HNO 3 or H 2O 2, and the number and nature of oxygenated functions introduced were determined by a combination of simplified Boehm's titration, XPS, BET, and DRIFTS. These functions were then used as anchors for model Pd precursors through covalent bonding. The underlying ligand-exchange mechanism was elucidated through detailed XPS studies. The thermal activation of the grafted materials was followed by in situ mass spectrometry, which demonstrated that it consisted of ligand losses. The activated samples were characterized by SEM, XRD, CO chemisorption, and XPS and used in the reduction of 2-methyl-2-nitropropane (MNP) into t-butylamine (TBA). The catalytic activity was shown to be correlated with the initial carbon acidity and the Pd dispersion.

Group 10 Metal Aminopyridinato Complexes: Synthesis, Structure, and Application as Aryl-Cl Activation and Hydrosilane Polymerization Catalysts

(4-Methyl-pyridin-2-yl)(trimethylsilanyl)amine (ApSi-H) and tert-butyl(4-methyl-pyridin-2-yl)amine (AptBu-H) were synthesized via salt metathesis and aryl amination reactions, respectively. Lithiation of these two aminopyridines using n-BuLi and the reactions with [(dme)NiCl2] (dme = dimethoxyethane) or [(cod)PdCl2] (cod = cyclooctadiene) in THF at low temperature gave rise--after workup in hexane--to group 10 amido compounds, [(ApSi)4Ni2], [(AptBu)2Pd], [(AptBu-H)(AptBu)2Ni], [(AptBu)3(C2H5O)3Ni3OLi(thf)], and [(AptBu)2Ni(tBupy)2] (tBupy = 4-tert-butylpyridine). The aminopyridinato complexes were characterized by X-ray crystal structure analysis. The highly strained binding situation of the aminopyridinato ligands suggested that these compounds might be efficiently converted into catalytically active species. The applications of some of the synthesized complexes as Suzuki cross-coupling catalysts (activation of aryl chlorides) are described and [(ApSi)4Ni2] is a rare example of a "phosphine-free" catalyst system. A number of late transition metal complexes were found to successfully catalyze polymerization of MeH2SiSiH2Me toward soluble, linear poly(methylsilane). Remarkable activity was observed for [(ApSi)2Pd].

High static pressure alters spin trapping rates in solution. Dependence on the structure of nitrone spin traps

Using a competitive spin trapping method, relative spin trapping rates were quantified for various short-lived radicals (methyl, ethyl, and phenyl radicals). High static pressure was applied to the competitive spin-trapping system by employing high-pressure electron spin resonance (ESR) equipment. Under high pressure (490 bar), spin trapping rate constants for alkyl and phenyl radicals increased by 10 to 40%, and the increase was dependent on the structure of nitrone spin traps. A maximum increase was obtained when tert-butyl(4-pyridinylmethylene)amine N-oxide (4-POBN) was used as a spin trap. Activation volumes (DeltaDeltaV(double dagger)) for the two spin trapping reactions were calculated to be -17-(-9) cm(3) mol(-1) for the 4-POBN system.

Synthesis, Structure, and Hydrophosphorylation of π‐Complexes Derived from tert‐Butyl(1,3‐dimethyl‐2‐butenylidene)amine and Homoligand Iron(0) and Group VIb Metal Carbonyls.

New iron(0), chromium(0), molybdenum(0), and tungsten(0) π-complexes containing η2-, η 3-, and η4-coordinated tert-butyl(1,3-dimethyl-2-butenylidene)amine ligands were synthesized under conditions of photochemical and thermal activation. The geometric, electronic, and energetic parameters of the coordinated 1,3-azadiene were calculated by nonempirical methods, and factors determining the mode of coordination were established. The obtained π-complexes reacted with dialkyl phosphonates in the presence of triethylamine to afford organometallic α-aminophosphonates; hydrophosphorylation in the absence of a catalyst gave the corresponding amidophosphate which then underwent rearrangement into α-aminophosphonate.

Synthesis, structure, and hydrophosphorylation of ?-complexes derived from tert-butyl(1,3-dimethyl-2- butenylidene)amine and homoligand iron(0) and group VIb metal carbonyls

New iron(0), chromium(0), molybdenum(0), and tungsten(0) π-complexes containing η2-, η 3-, and η4-coordinated tert-butyl(1,3-dimethyl-2-butenylidene)amine ligands were synthesized under conditions of photochemical and thermal activation. The geometric, electronic, and energetic parameters of the coordinated 1,3-azadiene were calculated by nonempirical methods, and factors determining the mode of coordination were established. The obtained π-complexes reacted with dialkyl phosphonates in the presence of triethylamine to afford organometallic α-aminophosphonates; hydrophosphorylation in the absence of a catalyst gave the corresponding amidophosphate which then underwent rearrangement into α-aminophosphonate.

Adsorption and Decomposition Studies of t-Butylamine, Diethylamine, and Methylethylamine on Si(100)−(2 × 1)

We have studied chemisorption and thermal decomposition of tert-butylamine (TBA), diethylamine (DEA), and methylethylamine (MEA) on Si(100)−(2 × 1) with synchrotron-based X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Adsorption at cryogenic temperature leads to molecularly intact chemisorption (dative-bonding via the nitrogen lone pair) and dissociative chemisorption via N−H scission, producing distinct N 1s peaks at binding energies of 401.1 and 398.2 eV, respectively. The corresponding change for C 1s core level is also significant, and a 0.9 eV shift toward lower binding energy is found for DEA, suggesting a high degree of charge redistribution between two adsorption configurations. Upon warming to room temperature, the adsorbed amines almost completely transform into dissociative chemisorbed forms. Thermal decomposition of TBA at elevated temperatures produces desorption species of isobutylene via γ-H elimination, hydrogen cyanide, and H2. In comparison, DEA and M...

Application of an alkyl-diol silica precolumn in a column-switching system for the determination of meloxicam in plasma

The group of LiChrospher alkyl-diol silica (ADS) phases that make part of the unique family of restricted-access materials, have been developed as special packings used in the liquid chromatographic integrated sample processing of biofluids. The advantage of these phases lies in the possibility of direct injection of untreated plasma. An on-line elimination of the protein matrix is achieved with a quantitative recovery together with an on-column enrichment. The present method describes a hand-operated on-line switching high-performance liquid chromatographic system for the determination of meloxicam. Spiked plasma samples were introduced on the ADS precolumn using a 0.05 M phosphate buffer, pH 6.0. After washing with the buffer the ADS column was backflushed with the mobile phase 0.05 M phosphate buffer–30% (v/v) acetonitrile (ACN)–25 mM t-butylamine (TBA) at a pH of 7.0, thus transferring the analyte to the analytical column LiChrocart 125-4 LiChrospher RP-8. The eluent was monitored by a UV-detector set at 364 nm. The developed column-switching method is fully applicable to plasma injections.

The oligomer of 1,2,3-trihydroxybenzene with benzaldehyde

A linear oligomer of benzaldehyde with 1,2,3-trihydroxybenzene was synthesised and characterized. The oligomer has a quinonic end group that leads to a solvatochromic property and interacts with a variety of amines. In aprotic medium the oligomer has two non-equivalent intra-molecular H-bonded quinonic states arising from keto– enol tautomerism, one having the carbonyl and olefinic group at the 1,4-disposition ( X) whereas in the other the carbonyl and olefinic groups are at the 1,2-disposition ( Y). Thus, in acetonitrile both forms exist and the X and Y states have their characteristic absorption maximum at 500 and 427 nm, respectively. In protic medium a highly ordered structure with the hydrophobic and hydrophilic part projecting apart produces a structure ( Z) having inter-molecular hydrogen-bonding with solvent which has a characteristic absorption at 475 nm. Non-stoichiometric amounts of various primary, secondary and tertiary amines interact with the oligomer providing stability to either of the forms or generating an anion by which the absorption maximum changes. For example, the oligomer interacts with t-butylamine, and this interaction changes the absorption maximum to 566 nm. The solution on further treatment with mineral acid (HCl) gives a new absorption maximum at 475 nm with a distinct color change. The absorptions can be changed back and forth by alternate addition of hydrochloric acid and t-butylamine. However, the characteristic changes that take place in the optical spectra of the oligomer in acetonitrile with different amines are highly substrate-dependent. For example the amines like ammonia, ethylamine, iso-propylamine, n-butyl amine, t-butyl amine, ethylenediamine, and pyridine cause loss of absorption at 427 and 500 nm and lead to growth of new absorption at 566 nm; whereas amines like benzidine, o-diaminobenzene, m-iodoaniline, m-nitroaniline, and p-hydroxyaniline enhance the original absorbance at 427 nm at the cost of absorption at 500 nm without leading to a new absorption. Some amines like 1-naphthylamine, 1,7-diaminonaphthalene, p-iodoaniline, and p-methoxyaniline increase the absorbances at 427 and 500 nm, whereas aniline, o-methylaniline, m-methylaniline, and diphenylamine do not significantly affect the spectra of the oligomer. The electrochemical study of the oligomer with 1,4-phenylenediamine shows that redox potentials of the bound state of the oligomer with 1,4-phenylenediamine shifts from the unbound state, for example, 1,4-phenylenediamine with the oligomer has two quasireversible couples at E 1/2 at 259 and 822 mV in contrast to the two reversible couples of free 1,4-phenylenediamine at 334 and 863 mV, respectively.

Nucleophilic substitution induced by electron transfer at the bridgehead of polycyclic alkanes: competition between polar and radical pathways.

A series of 2,5(or 1,4)-dihaloadamantanes (4 and 5, X = Y = halogens) and 9,10-dihalotriptycenes (7, X = Y = halogens) as well as two 5-halo (X) adamantan-2-ones (6, Y = O, X = Br and I) have been treated with Me(3)SnLi in THF in the absence and presence of tert-butylamine (TBA) and dicyclohexylphosphine (DCHP). The product distributions of these reactions have been established by (13)C and (119)Sn NMR spectroscopy, vapor-phase chromatographic analyses, and GC/MS. The former compounds (4 and 5) appear to react exclusively by a free-radical chain process (S(RN)1 mechanism) to yield tin substitution products. By contrast, the triptycenes react predominantly by a polar mechanism initiated by the formation of a carbanion. In the case of the halo ketones (6, Y = O, X = Br and I), a mechanistic divergence of the reaction was unexpectedly encountered. Whereas the bromo ketone provides the substitution product (6, Y = O, X = SnMe(3)) in good yield (ca. 75%), apparently by a radical pathway, the iodo ketone yields a fragmentation product (ca. 95% yield) by a polar mechanism. This mechanistic switch highlights the importance of the electronegativity of the leaving group as well as substituent-induced electron delocalization as molecular factors governing the competition between radical and polar pathways.

Viscosity of Aqueous Solutions of n-butylamine, sec-butylamine and tert-butylamine

Viscosities of the systems, water (W) + n-butylamine (NBA), W + sec-butylamine (SBA) and W + tert-butylamine (TBA) have been measured in the temperature range 298.15–323.15K. The viscosities (η) and excess viscosities (ηE) have been plotted against mole fraction of amines (X 2). On addition of amines to water, viscosities first increase rapidly, then pass through maxima at 0.2 mole fraction of amines and then decline continuously as the addition of amines is continued. ηE show large positive values, with maxima also at 0.2 mole fraction of amines. The maxima of the curves of η and ηE vs. mole fraction of butylamines follow the order, W + TBA > W + SBA > W + NBA. The ascending part of the η vs. X 2 curves in the water-rich region is explained by the hydrophobic hydration caused by the hydrocarbon tails and the hydrophilic effect due to — NH2 group of amines. Following the maxima, amine - amine association is preferred, which accounts for the steady decrease of viscosity up to the pure state of amines.

Addition of tert-Butylamine to Diethyl Alkynephosphonates Catalyzed by CuCl

Addition of tert-Butylamine to Diethyl Alkynephosphonates Catalyzed by CuCl

Solution Structure of the Inclusion Complexes between Cyclodextrins and Dialkylamines: An NMR Study

Interaction between chemically modified cyclodextrins (CDs) and benzyl(tert-butyl)amine (1), tert-butyl(methyl)amine (2) and benzyl(methyl)amine (3) has been investigated by NMR spectroscopy. The experimental results revealed that the complexation-induced shifts for the reported amines were more pronounced for the carbon atoms than for the protons. These shift variations were successfully exploited for determining the association constants with heptakis(2,6-O-dimethyl)-β-CD, which were found to be 295, 119 and 101 M−1 for 1, 2 and 3, respectively. Features of the geometries of the amine/DM-β-CD complexes were deduced by measuring the NOE intermolecular interactions between host and guest protons. These data made it possible to elucidate fully the nature of the amine/CD complexes and provided information complementary to that previously obtained by EPR spectroscopy on the complexation of the closely related nitroxide/CD paramagnetic complexes.

Solution Structure of the Inclusion Complexes between Cyclodextrins and Dialkylamines: An NMR Study

Interaction between chemically modified cyclodextrins (CDs) and benzyl(tert-butyl)amine (1), tert-butyl(methyl)amine (2) and benzyl(methyl)amine (3) has been investigated by NMR spectroscopy. The experimental results revealed that the complexation-induced shifts for the reported amines were more pronounced for the carbon atoms than for the protons. These shift variations were successfully exploited for determining the association constants with heptakis(2,6-O-dimethyl)-β-CD, which were found to be 295, 119 and 101 M−1 for 1, 2 and 3, respectively. Features of the geometries of the amine/DM-β-CD complexes were deduced by measuring the NOE intermolecular interactions between host and guest protons. These data made it possible to elucidate fully the nature of the amine/CD complexes and provided information complementary to that previously obtained by EPR spectroscopy on the complexation of the closely related nitroxide/CD paramagnetic complexes.

Excess Molar Volumes of Aqueous Solutions of Butylamine Isomers

Excess molar volumes (VE ) and average thermal expansivities (α) of the systems, water (W) + n-butylamine (NBA), W + sec-butylamine (SBA), and W + tert-butylamine (TBA), have been calculated from the density data at temperatures ranging from 298.15–323.15 K. The VE and α values have been plotted as functions of mole fraction of amines. The systems show large negative excess volumes, magnitude of which varies in the order, W + TBA > W + SBA > W + NBA. The curves are found to be symmetrical along the composition axis, with minima occurring at 0.5 mole fraction of butylamines. The negative excess volumes have been interpreted primarily by two effects: (i) strong chemical interaction leading to the formation of 1:1 complexes through H-bonding and (ii) hydrophobic hydration causing significant contraction of volume.

X-ray photoelectron spectroscopy study of TiN films produced with tetrakis(dimethylamido)titanium and selected N-containing precursors on SiO2

Low pressure chemical vapor deposition TiN films were produced on SiO2 by codosing tetrakis(dimethylamido)titanium (TDMAT) with selected N-containing precursors. The films were grown at total pressures ranging from 10−4 to 10−3 Torr and temperatures between 523 and 773 K. Film composition and chemical states were determined, without exposure to ambient pressure, using x-ray photoelectron spectroscopy (XPS). Our primary goal was to evaluate how precursor ligands affect C and N incorporation into TiN films. To this end, methylhydrazine (MH), dimethylhydrazine (DMH), and 1-aminopiperidine (AP) were chosen for their steric differences, and t-butylamine (TBA) and aniline allowed us to assess how C and N incorporation are affected by the C–N bond in the aminolike compounds versus the N–N bond in the hydrazinelike compounds. At all growth temperatures, a decrease in the carbon concentration and an increase in the N concentration were observed for the MH and DMH cases when compared to TDMAT alone, while C content increased for aniline. AP caused only a slight reduction of C at temperatures of 673 K and above. Growth temperature affected film composition and the chemical states of C, N, and Ti. At 623 K, DMH and MH reduced the C/Ti ratio from 1.0 with TDMAT alone to 0.2, while aniline increased C/Ti to 2.0 and AP and TBA had little effect. The addition of the N-containing precursors causes the XPS C 1s peak to broaden and shift to higher binding energy; the N 1s peak also broadened, suggesting that, compared to TDMAT alone, more C–N bonds are formed. Furthermore, the Ti 2p peak shifted to higher binding energy and became broader upon codosing, suggesting the incomplete conversion of Ti (IV) to Ti (III) in the TiN film. Postdosing with MH and DMH supports the conclusion that surface reactions occur between TDMAT and the hydrazinelike precursors.

Cyclopolymerization of amine-linked diacrylate monomers

New diacrylate monomers for cyclopolymerization were synthesized from the reaction of ethyl α-chloromethylacrylate (ECMA) and t-butyl α-bromomethyl acrylate (TBBr) with aniline, adamantyl amine, t-butyl amine, cyanamide, and 4-tetradecyl aniline in yields of ca. 50–70%. Bulk and solution polymerizations with azobisisobutyronitrile (AIBN) at 60–85°C gave soluble cyclopolymers with Mn and Mw ranging from 10,000–30,000 and 12,000–40,000, respectively. The ECMA–cyanamide derivative only gave crosslinked polymers. 1H and 13C solution NMR indicated high cyclization efficiency (>93%). A prototype NLO polymer was synthesized from the reaction of the TBBr–aniline cyclopolymer with tetracyanoethylene. The p-hydroxyaniline derivative of ECMA was synthesized and used for further derivatizations; for example, the benzoate ester was made and polymerized (Mn = 21,260 and Mw = 40,317). The ester groups of the TBBrndash;aniline polymer were hydrolyzed completely to give a polymer with both acid and base moieties. DSC thermograms showed glass transitions of 132°C for the ECMA–aniline derivative, 192°C for the ECMA–adamantyl derivative, 53°C for the TBBr–tetradecylaniline derivative, and 120° for the ECMA–p-benzoylaniline derivative. The ECMA–t-butyl amine polymer showed no obvious Tg. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2111–2121, 1997

On the Reaction of Trichloromethylphosphonothioic Acid with Tertbutylamine and Hexamethyldisilazane

The reactions of trichloromethylphosphonothioic dichloride CCl3 P(S)Cl2 with tertbutylamine (TBA) or hexamethyldisilazane (HMDSA) yield the corresponding amides. Both amides, i.e. CCl3 P(S)(NH-But )2 (I) and CCl3 P(S)(NH-SiMe3 )2 (II), were isolated

Synthesis and beta-adrenergic activities of R-fluoronaphthyloxypropanolamine.

Many biogenic amines where an aromatic proton is substituted with fluorine have exhibited pharmacological properties that are dependent on the position of fluorine on the aromatic ring. For example, 6-fluoroepinephrine is selective for alpha-adrenergic receptors whereas the 2-fluoroisomer is selective for beta-receptors. Aryloxypropanolamines are beta-receptor agonists or antagonists, depending on the aryl group and its substituents. We therefore hypothesized that fluorine substitution on the atomatic ring could lead to significant biological effects in this class. A target with fluorine on naphthyl group of a known beta-antagonist was chosen for investigation. Synthesis of the target compound began with fluoronaphthalene and involved introduction of 4-hydroxy group by Friedel-Crafts acylation followed by Baeyer Villiger oxidation. The side chain was introduced stereoselectively using the chiral synthon (2R)-glycidyl 3-nitrobenzenesulfonate, a Sharpless epoxidation technique. The epoxide was opened with t-butyl amine. HPLC methods were used to characterize %ee of the enantiomer. The target compound was synthesized in several hundred milligram quantity, and in good yield and high enantiomeric excess, showing practicality of the synthetic scheme. It exhibited potent binding activities on beta-adrenergic receptors, and was found to be two times selective for beta 2-receptors over beta 1. The current report demonstrates that aromatic fluorine substitution on beta-adrenergic ligands can be achieved, and that such can be used to obtain binding selectivity between beta receptors.

Ion chromatography of amylamine and tert.-butylamine in pharmaceuticals

Ion chromatographic (IC) methods have been developed for the assay of amylamine in BMS-181 866-02 and tert.-butylamine (TBA) in BMS-188 494-04. BMS-181 866-02 is the penultimate intermediate in the synthesis of a novel thromboxane antagonist, BMS-180 291-02, which is undergoing clinical trials. Amylamine may be present as a trace impurity in BMS-181 866-02. BMS-188 494-04 is the TBA salt of the prodrug ester of BMS-187 745, a novel oral hypocholesterolemic agent. Chromatographic separations were accomplished under isocratic conditions using a Dionex CS-14 column with conductivity detection. The methods differ only in the composition of the methanesulfonic acid-acetonitrile mobile phase. The detection limit and minimum quantifiable levels for amylamine were 0.01% and 0.02%, respectively. The method was linear over the range studied (1–12.5 μg/ml, n = 7, r = 0.9993). The method for TBA was linear from 5 to 30% (w/w) (50–300 μg/ml, n = 8, r = 0.9993) of working sample concentration (1 mg/ml BMS-188 494-04). The precision and accuracy of the methods are presented.

Synthesis and x-ray crystal structure of a bis(trimethylsiloxy)ruthenium(iii) complex

Treatment of the cis-dioxoruthenium(VI) complex, cis-[Ru VI(L)O 2](PF 6) 2 (L = N,N,N′,N′-3,6-hexamethyl-3,6-diazaoctane-1,8-diamine) with tert-butyl(trimethylsilyl)amine in benzene at room temperature resulted in the formation of cis-[Ru III(L) (OSiMe 3) 2](PF 6) ( 1), which was characterized by X-ray diffraction crystal analysis.