Crystallization analysis

This is a simplified formula for tartar emetic, for X-ray crystal analysis and infrared studies indicate that the. Sb is a part of the antimonate anion [Sb(OH)4] and forms part of a cyclic system. 

The 6-methylacetylamino-l,2,3,4-tetrahydroquinoline, after nitration and separation of isomers, following reduction and deprotection, gave the 7-amino-6-methylamino derivative, which cyclized with cyanogen bromide. Alkylation of the cyclization products afforded inhibitors of thymidylate synthase, 5-substituted 2-amino-l//-l-methyl-5,6,7,8-tetrahydroimidazo[4,5-g]quinolines 136, designed for use in iterative protein crystal analysis (Scheme 42) (92JMC847). 

The X-ray crystal analysis of 5-trimethylsilanyl-4-trimethylsilanylethynyl-l//-pyrazole-3-carboxylic acid ethyl ester was obtained only with / = 0.17 because the crystals of the molecule diffracted extremely weakly and only a very limited data set was available. This means that although the gross stereochemistry of the molecule has been determined, individual bond lengths are not reliable (88JOM247). 

The indazole alkaloid Nigellidine (269) (Scheme 88) which was described as a zwitterion, was detected in the seeds of Nigella saliva L. (Ranunculaceae) (95TL1993), which is an erect annual plant found in South Asia and is widely cultivated. The seeds are commonly believed to have carminative, stimulatory and diaphoretic properties (75PHA2759). An X-ray single crystal analysis was performed on the methyl chloride. It is... 

According to crystal analysis performed by Stomberg [173], Na2NbOF5 is made up of sodium ions and isolated NbOF52 complex ions and is similar in structure to FeWC>6. NbOFs2" polyhedrons comprise slightly distorted octahedrons that are located in one of two equivalent positions. The niobium atom is shifted 0.234 A from the equatorial plane towards the oxygen atom. 

In contrast to the other measurements, the X-ray crystal analysis of thieno[3,4-d]thiepin shows an azulene-like, planar structure.30... 

In the as-synthesized MFI-crystals the tetrapropylammonium (TPA) ions are occupying the intersections between the straight (parallel) and the sinusoidal channels of the zeolite, thus providing an efficient pore filling. The detailed structure of as-synthesized MFI-TPA has been elucidated by X-ray single crystal analysis (ref. 3). Also the combination tetrabutyl-Ztetraethylammonium can be applied as template in MFI-synthesis. A 1 1 build-in is found then (Fig. 1). When only tetrabutylammonium is available as template, the MEL (ZSM-11) lattice is formed with another distance between the channel intersections. 

X-ray single crystal analysis Data collection. Siemens SMART IK CCD. Diffractometer. Data collection by SMART (Siemens, 1995) cell refinement SMART data reduction SAINT (Siemens, 1995) program(s) used to solve structure SHELXS97 (Sheldrick, 1997) program(s) used to refine structure SHELXL97 (Sheldrick, 1997) molecular graphics XP in SHELXTL (Sheldrick,... 

We could identify that both phosphorous atoms stay coordinated to the metal (PP coupling among metal at 40,5 Hz). Crystallization of the complex in CHCls/hexane allowed an x-ray single crystal analysis that clearly demonstrates the coordination chemistry as shown above. 

For ruthenium, special precursors are required to synthesize defined bidentate diphosphine complexes. With Taniaphos for instance, it is possible to synthesize such complexes starting from unusual rathenium(ll) species. The complexes were characterized by NMR and single crystal analysis. 

Additionally, the authors wotrld like to thank Dr. Bats (University of Frankfurt am Main, Germany) for preparing x-ray single crystal analysis. 

The structure of dimer XI (X, where n = 2), obtained by x-ray single crystal analysis (Figure 1), shows that the desired skeletal stabilization based upon 1,4- condensation units has been achieved. 

Since 2-pyridone (24a, Table 3) exists as an equilibrium mixture with 2-hydroxy-pyridine (25a)14), it is difficult to isolate 24a in a pure state. However, the complexation method using inclusion hosts is applicable for the isolation of keto-form 24a in a pure state. For example, 24a was isolated by inclusion complexation (1 2 complexes) with 1 (26a) (Table 3) and with 3 (27a) (mp 151-153 °C), respectively. Both 26a and 27a do not contain the enol form (25a). The structure of 26a was studied by X-ray crystal analysis (Figs. 7, 8)12>. Inclusion of the keto-form is understandable, because 1 and 3 form more stable hydrogen bonds with the carbonyl oxygen of the... 

Anantawaraskul, S., Soares,. B. P. and Wood-Adams, P. M. Fractionation of Semicrystalline Polymers by Crystallization Analysis Fractionation and Temperature Rising Elution Fractionation. Vol. 182, pp. 1-54. 

Of special interest (see Table II) is the structure of compound XVI, obtained in a reaction with thermodynamic control, and its sulfide (XVII), as both molecules contain the P—H bond. Infrared, Raman, and NMR studies as well as dipole moment measurements showed that the P—H bond was axial in these compounds. In some cases the conclusions of NMR and dipole moment studies were verified by X-ray single-crystal analysis. 

Rytter et al. reported polymerizations with the dual precatalyst system 14/15 in presence of MAO [30]. Under ethylene-hexene copolymerization conditions, 14/MAO produced a polymer with 0.7 mol% hexene, while the 15/MAO gave a copolymer with ca. 5 mol% hexene. In the mixed catalyst system, the activity and comonomer incorporation were approximate averages of what would be expected for the two catalysts. Using crystallization analysis fractionation (CRYSTAF) and differential scanning calorimetry (DSC) analysis, it was concluded in a later paper by Rytter that the material was a blend containing no block copolymer [31],... 

To the resultant triethyl phosphonoformate (105 g, 0.5 mol) was added sodium hydroxide solution (250 ml, 10 M) over a period of 15 min at ambient temperature. The solution became hot, and ethanol by-product boiled off from the reaction mixture. Upon cooling, a precipitate formed, which was recrystallized from water to give colorless crystals of the pure trisodium phosphonoformate hexahydrate (27.5 g, 19%), which exhibited IR and NMR spectra and x-ray crystal analysis in accord with the proposed structure. 

N-benzyladamantyl-2-imines, and 2-methyleneadamantanes were studied (352, 353). In particular, X-ray single-crystal analysis confirmed the configuration of the oxathiazoline 185, resulting from the favored attack of nitrile oxide on the 5-fluoroadamantane-2-thione. 2-Silyl-substituted oxathiazole 186 was synthesized by the 1,3-dipolar cycloaddition reaction of phenyl triphenylsilyl thioketone with 4-chlorobenzonitrile oxide (354). 

Other than classical H and 13C NMR spectra which have been reported for these compounds, no detailed studies have appeared in the literature. One X-ray crystal analysis of the TBDMS-protected alcohol analog of acid 368 has been carried out for structural proof. 

In 1978, on the basis of a few measurements of urine calcium and phosphate excretion as well as an awareness of the previously mentioned work regarding the amounts of calcium and phosphate normally accreted in utero and postnatally, it became apparent that the demineralization, fractures and rickets we were seeing in our infants were caused by calcium deficiency. Consequently we increased the amount of calcium added to the parenteral alimentation solutions. If more than 12.5 mM of the calcium were added to a liter of hyperalimentation solution, gross precipitation would occur in the feeding solution. If 10 mM of calcium were added per liter, crystalline precipitated began to build up on the inside of our barium-impregnated silicone rubber central venous catheters. This crystalline precipitate resulted in gradual occlusion and functional loss of these lines. After several false starts and six lost catheters, chemical and crystal analysis showed that the precipitate inside these catheters was CaHPO. ... 

Single crystal analysis of polysilanes is rare, since the structural variations in polymer samples usually preclude the formation of crystals of sufficient quality and size, although there are a few reports. The structure of l,6-bis[(i )-2-phenylpropyl]dodecapropylhexasilane, 5(R), with terminal chiral groups has been reported 15 the conformation is M-screw sense all-transoid with backbone dihedral angles in the range —172° to —177°, and was described as a 157 helix the structure is shown in Figure 21. 

X-ray crystal analysis indicates that the DABCO/CBiq complex consists of alternating planes of the diamine and carbon tetrabromide in which each acceptor is bound to two donor units. The quinuclidine/CBr4 complex consists of pairs of donor-acceptor systems in which every quinuclidine molecule is bound to only a single molecule of carbon tetrabromide. 

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