- Nucleation and growth of ZnO in organic solvents - An in situ study
-
ZnO is a metal oxide material which possesses versatile properties and applications. Therefore, the target-oriented preparation of ZnO has become a major issue. Many preparation techniques involve bottom-up methods from precursor solutions. In the current contribution, a special precursor system is described that enables a fine-control of kinetic parameters for the nucleation and growth of ZnO in various organic solvents. A large variety of analytical techniques could be applied in an in situ fashion to probe for the ZnO formation at all times and all length scales. Among the analytical techniques are UV/vis, Raman, Fluorescence, X-ray absorption, 1H NMR-spectroscopy, dynamic light-scattering, and TEM. Three different regimes for nucleation and growth with different characteristics could be identified. Furthermore, the effect of different parameters on the resulting ZnO particle size was investigated.
- Lizandara-Pueyo,Van Den Berg,De Toni,Goes,Polarz
-
-
Read Online
- Selective oxidation of the alkyl ligand in rhenium(V) oxo complexes
-
Rhenium(V) oxo alkyl triflate compounds (HBpz3)ReO(R)OTf [R = Me (4), Et (5), n-Bu (6); HBpz3 = hydrotris(1-pyrazolyl)borate; OTf = OSO2CF3, triflate] are formed on sequential reaction of (HBpz3)ReOCl2 with dialkyl zinc reagents and AgOTf. These triflate compounds are rapidly oxidized at ambient temperatures by oxygen atom donors pyridine N-oxide (pyO) and dimethyl sulfoxide (DMSO) to give (HBpz3)ReO3 (7) and the corresponding aldehyde. In the cases of 5 and 6 this transformation is quantitative. The addition of 2,6-lutidine to a low-temperature oxidation of 5 by DMSO redirects the reaction to form cis-2-butene instead of acetaldehyde. These oxidation reactions do not proceed through alkoxide intermediates, as shown by independent studies of alkoxide oxidations. Reaction of 5 with pyO or DMSO at -47°C results in the formation of intermediates which are assigned as ylide or 'trapped-carbene' complexes [(HBpz3)ReO(OH){CH(L)CH3}]OTf (L = py (8) or SMe2 (9), respectively). Mechanistic studies and analogies with related systems suggest that oxygen atom transfer to 4-6 forms [(HBpz3)ReO2R]+. Transfer of an α-hydrogen from the alkyl group to an oxo ligand then forms an alkylidene complex which is trapped by SMe2 or py to give the observed intermediates. Further oxidation of the ylide complex gives the aldehyde.
- DuMez, Darin D.,Mayer, James M.
-
-
Read Online
- Electrophilic Amination with Nitroarenes
-
An exceptionally general electrophilic amination, which directly transforms commercially available nitroarenes into alkylated aromatic aminoboranes with zinc organyl compounds was developed. The reaction starts with a two-step partial reduction of the nitro group to a nitrenoid, which is used in situ as the electrophilic amination reagent. To facilitate isolation, the resulting air- and moisture-sensitive aminoboranes were reacted with a range of electrophiles. The method not only represents a direct transformation of nitro compounds into electrophilic amination reagents but also provides an elegant alternative to dehydrocoupling methods for the generation of aminoboranes.
- Rauser, Marian,Ascheberg, Christoph,Niggemann, Meike
-
supporting information
p. 11570 - 11574
(2017/09/11)
-
- Molecular Zinc Species with Ge-Zn and Sn-Zn Bonds: A Reversible Insertion of a Stannylene into a Zinc-Carbon Bond
-
The tetrylenes Ge(ArMe6)2 and Sn(ArMe6)2 (ArMe6 = C6H3-2,6-(C6H2-2,4,6-(CH3)3)2) reacted with dimethylzinc to afford the insertion products (ArMe6)2Ge(Me)ZnMe (1) and (ArMe6)2Sn(Me)ZnMe (3), which feature Ge-Zn and Sn-Zn bonds as well as two-coordinate zinc atoms. Crystals of 1 were found to be unsuitable for X-ray crystallography, so the ethyl-substituted (ArMe6)2Ge(Et)ZnEt (2) was synthesized in a parallel way to provide crystals suitable for X-ray studies. These showed the structure to be similar to that of 3. The reaction of Pb(ArMe6)2 with dimethylzinc yielded ArMe6ZnMe with a linearly coordinated zinc atom via ligand exchange but no characterizable, new lead product was obtained. The reaction of Sn(ArMe6)2 with dimethylzinc is reversible in hydrocarbon solution at room temperature and displayed a dissociation constant Kdiss and a ΔGdiss of 0.0028(5) and 14(4) kJ mol-1 at 298 K, respectively. Compounds 1-4 were characterized by NMR and IR spectroscopy as well as by X-ray crystallography for 1, 3, and 4.
- Erickson, Jeremy D.,Riparetti, Ryan D.,Fettinger, James C.,Power, Philip P.
-
supporting information
p. 2124 - 2128
(2016/07/11)
-
- A dimethyl zinc preparation method
-
The invention belongs to a preparation method for dimethylzinc. The method includes the following steps that zinc halide is added into a reaction kettle under inert gas protection, then trimethylaluminum is dropwise added under the stirring condition, the reaction speed is controlled through the addition speed of the trimethylaluminum, stirring continues for reaction of 3 h-5 h after addition of the trimethylaluminum is finished, then the temperature of the reaction kettle is adjusted to be 42 DEG C-90 DEG C and kept for 2 h-3 h, and distilled Zn(CH3)2 is collected; diethylzinc is dropwise added into the reaction kettle, the temperature of the reaction kettle is controlled to be 91 DEG C-120 DEG C, distilled Zn(CH3)2 is collected, the temperature of the reaction kettle is kept within 91 DEG C-120 DEG C after addition of the diethylzinc is finished, and Zn(CH3)2 continues being collected for 1 h-3 h. According to the method, raw materials of the dimethylzinc are easy to get, reaction is simple, control is easy, industrial production is facilitated, the reaction yield is high, and the total yield reaches more than 90%.
- -
-
Paragraph 0011-0013
(2020/02/10)
-
- Exchange of alkyl and tris(2-mercapto-1-t-butylimidazolyl)hydroborato ligands between zinc, cadmium and mercury
-
Abstract The tris(2-mercaptoimidazolyl)hydroborato ligand, [TmBut], has been used to investigate the exchange of alkyl and sulfur donor ligands between the Group 12 metals, Zn, Cd and Hg. For example, [TmBut]2Zn reacts with Me2Zn to yield [TmBut]ZnMe, while [TmBut]CdMe is obtained readily upon reaction of [TmBut]2Cd with Me2Cd. Ligand exchange is also observed between different metal centers. For example, [TmBut]CdMe reacts with Me2Zn to afford [TmBut]ZnMe and Me2Cd. Likewise, [TmBut]HgMe reacts with Me2Zn to afford [TmBut]ZnMe and Me2Hg. However, whereas the [TmBut] ligand transfers from mercury to zinc in the methyl system, [TmBut]HgMe/Me2Zn, transfer of the [TmBut] ligand from zinc to mercury is observed upon treatment of [TmBut]2Zn with HgI2 to afford [TmBut]HgI and [TmBut]ZnI. These observations demonstrate that the phenomenological preference for the [TmBut] ligand to bind one metal rather than another is strongly influenced by the nature of the co-ligands.
- Kreider-Mueller, Ava,Quinlivan, Patrick J.,Rong, Yi,Owen, Jonathan S.,Parkin, Gerard
-
p. 177 - 183
(2015/08/18)
-
- Nickel-catalyzed C-F bond activation and alkylation of polyfluoroaryl imines
-
In this paper we show the C-F bond activation and alkylation in polyfluoroaryl imines. An active trimethylphosphine supported nickel-catalyzed cross-coupling reaction of polyfluoroaryl imines with ZnMe2 under mild conditions is described. According to the in situ 19F NMR spectroscopic data, the substrates are quantitatively converted into di-methylation products, while mono-methylation can also be realized under the controlled conditions in moderate yields. Apart from ZnMe2, other organozinc regents were tried in this system. However, due to the nucleophilicity and steric hindrance, they show much lower reactivity than ZnMe2. Only in the case of benzylic zinc chloride, the dibenzylation product can be obtained quantitatively by raising temperature to 90 °C. The results reported here will benefit the development of C-F bond activation as well as the diversity of Schiff bases.
- Yang, Xiuxiu,Sun, Hongjian,Zhang, Shumiao,Li, Xiaoyan
-
-
- Fused Bicyclic Kinase Inhibitors
-
Compounds of Formula I, as shown below and defined herein: pharmaceutically acceptable salts thereof, synthesis, intermediates, formulations, and methods of disease treatment therewith, including treatment of cancers, such as tumors driven at least in part by at least one of RON, MET or ALK. This Abstract is not limiting of the invention.
- -
-
Page/Page column 23-24
(2011/11/30)
-
- METHODS FOR PREPARING DIORGANOZINC COMPOUNDS
-
There are provided methods for preparing the diorganozmc compounds of formula R2Zn (I or Ia), where R is a defined organic radical, and the two R groups can be the same or different The starting material is the zinc compound ZnX2 (II) or R2ZnX (IIa), where X is a defined anion and R2 is a defined organic radical. The zinc reagent of type II is combined with a Grignard reagent and also, when X is Cl or Br, with an alkali metal reagent (VI) to form the diorganozinc product (I or Ia). Also provided are methods for preparing the zinc alcoholates of formula Zn(OR1)2 by reaction of ZnX2, where X = Cl or Br, with an alkali metal reagent of the formula MOR1, where M = Na or K, and where R1 is a defined organic radical.
- -
-
Page/Page column 20
(2009/01/20)
-
- CRF1 RECEPTOR LIGANDS COMPRISING FUSED BICYCLIC HETEROARYL MOIETIES
-
Substituted heteroaryl fused pyridine, pyrazine, and related heterobicyclic compounds that act as selective modulators of CRF1 receptors are provided. These compounds are useful in the treatment of a number of CNS and periphereal disorders, particularly stress, anxiety, depression, cardiovascular disorders, gastrointestinal disorders, and eating disorders. Methods of treatment of such disorders as well as packaged pharmaceutical compositions are also provided. Compounds provided herein are also useful as probes for the localization of CRF receptors and as standards in assays for CRF receptor binding. Methods of using the compounds in receptor localization studies are given.
- -
-
Page/Page column 85
(2008/12/07)
-
- Covalent palladium-zinc bonds and their reactivity
-
Photolysis of (FPNP)Pd-Et in the presence of Et2Zn leads to the formation of (FPNP)Pd-Zn-Pd(PNPF), the first example of a compound with a covalent Pd-Zn bond. The Royal Society of Chemistry.
- Fafard, Claudia M.,Chen, Chun-Hsing,Foxman, Bruce M.,Ozerov, Oleg V.
-
p. 4465 - 4467
(2008/09/16)
-
- Preparation of Organozinc and Organocadmium Compounds from the Metals and Alkyl Halides in the Presence of Stimulating Systems Based on a Derivative a Transition Metal and an Organometallic Compound
-
Full and mixed alkyl derivatives of zinc and cadmium were prepared from these metals and organic halides in the presence of stimulating systems necessarily containing a transition metal derivative and an organometallic compound capable of reducing this derivative under the process conditions. Such stimulating systems make it possible to introduce selectively organic halides (iodides, bromides, chlorides) into the reaction with zinc and cadmium to obtain the corresponding mixed organometallic compounds.
- Eremeev,Danov,Skudin,Sakhipov
-
p. 556 - 559
(2007/10/03)
-
- Preparation and structural characterization of trimethylsilyl-substituted germylzinc halides, (Me3Si)3GeZnX (X = Cl, Br, and I) and silylzinc chloride, R(Me3Si)2SiZnCl (R = SiMe3 and Ph)
-
The trimethylsilyl-substituted germylzinc halides, (Me3Si) 3GeZnX (X = Cl, Br, and I), and silylzinc chlorides, R(Me3Si)2SiZnCl (R = SiMe3 and Ph) have been prepared and their molecular structures have been full determined by spectroscopic and single-crystal X-ray diffraction methods. The germylzinc halides and silylzinc chlorides have dimeric structures consisting of two μ-halogen atoms. The reactivity of germylzinc chloride with substrates is also examined.
- Nanjo, Masato,Oda, Takashi,Mochida, Kunio
-
p. 100 - 108
(2007/10/03)
-
- Preparation and characterization of tris(trimethylsilyl)germylzinc chloride and bis[tris(trimethylsilyl)germyl]zinc
-
The molecular structure of (Me3Si)3GeZnCl (1) has been determined by single-crystal X-ray diffraction. The germylzinc chloride 1 has a dimeric structure consisting of two μ-Cl atoms. The compound 1 reacted with (Me3Si)3GeLi in diethyl ether to give [(Me3Si)3Ge]2Zn (2), quantitatively. The structure of bis(germyl)zinc 2 has been also elucidated by X-ray diffraction.
- Nanjo, Masato,Oda, Takashi,Mochida, Kunio
-
p. 108 - 109
(2007/10/03)
-
- Design, reactivities, and practical application of dialkylzinc hydride ate complexes generated in Situ from dialkylzinc and metal hydride. A new methodology for activation of NaH and LiH under mild conditions
-
We designed various dialkylzinc hydride 'ate' complexes, prepared from dialkylzinc and metal hydride, and investigated the reactivities (and the transference aptitude of ligands) of these zincates toward benzophenone. The results clearly reveal that dimethylzinc hydrides are the most powerful and selective zincates for the reduction of the carbony1 group. This complex reagent turned out to be effective for the reduction of esters and amides as well as aldehydes and ketones to the corresponding alcohols and amines with good to excellent yields under mild conditions. Furthermore, the method was successfully used for the highly selective 1,2-reduction of α,β-unsaturated carbonyl compounds, the regioselective ring-opening reduction of epoxides, and the chemoselective reduction of aldehydes in the presence of ketones. We also discuss and clarify the active species and the mechanism of this reduction using the diastereoselective reductions of some carbonyl compounds with an adjacent chiral center. Also, this reducing system was found to constitute a powerful tool for the stereoselective synthesis of syn- and anti-1,2-diols. Moreover, we developed the catalytic version of this reducing system. The LiH-Me2Zn-ultrasound system proved to be effective not only for the catalytic reduction of the carbonyl compounds and epoxides but also for the partial reduction (the conversion) of carboxylic acids to aldehydes. This system is a very attractive method for several reasons (good availability, low cost, and easy operation) and would be particularly useful for large- scale reductions.
- Uchiyama, Masanobu,Furumoto, Shozo,Saito, Mariko,Kondo, Yoshinori,Sakamoto, Takao
-
p. 11425 - 11433
(2007/10/03)
-
- Effects of ligand exchange reactions on the composition of Cd1-yZnyTe grown by metalorganic vapor-phase epitaxy
-
The metalorganic vapor-phase epitaxy (MOVPE) of cadmium zinc telluride (Cd1-yZnyTe) from dimethylcadmium (DMCd), dimethylzinc (DMZn), diethylzinc (DEZn), and diisopropyltelluride (DIPTe) was studied using on-line infrared spectroscopy to monitor the feed and effluent gases. The film composition was measured by X-ray diffraction. No zinc was incorporated into the film when DMCd and DMZn were used due to the very low reactivity of the latter compound. When DMCd and DEZn are tried, the films were nonuniform with Cd-rich films deposited at the reactor inlet and Zn-rich films deposited near the reactor outlet. This film profile was due to alkyl ligand exchange reactions between the group II precursors in the feed, producing DMZn, methylethylzinc (MEZn), methylethylcadmium (MECd), and diethylcadmium (DECd). The decomposition rates of these precursors vary over a wide range with DECd reacting at a 250 K lower temperature than DMZn. Since the organocadmium compounds were consumed at a much faster rate, CdTe was deposited first, while ZnTe was deposited downstream. The ligand exchange reactions explain why previous workers found it difficult to grow Cd1-yZnyTe alloys of uniform composition by MOVPE.
- Kappers, Menno J.,Wilkerson, Kerri J.,Hicks, Robert F.
-
p. 4882 - 4888
(2007/10/03)
-
- Methylzinc tetrahydroborate: Physical and chemical properties and crystal structure at low temperature
-
Methylzinc tetrahydroborate, MeZnBH4, has been prepared by two routes and initially characterized by elemental analysis and its spectroscopic properties. The structure has been determined by X-ray crystallography at 150 K [trigonal, space group R3c, a = b = 15.831(10), c = 8.36(2) A, Z = 18, R = 0.072] to reveal helical polymers in which MeZn+ and BH4- units alternate, with the latter functioning as a bidentate ligand with respect to both of the adjacent metal atoms. It thus resembles the structure of solid Be(BH4)2 with the difference that the zinc is five-co-ordinated, the Me and H ligands adopting a distorted square-pyramidal geometry. Chemical properties of methylzinc tetrahydroborate investigated include its thermal decomposition and its reactions with ammonia, dimethyl sulfide, triphenylphosphine and CO; disproportionation into Me2Zn and Zn(BH4)2 appears to be a common feature of its chemistry.
- Aldridge, Simon,Blake, Alexander J.,Downs, Anthony J.,Parsons, Simon,Pulham, Colin R.
-
p. 853 - 859
(2007/10/03)
-
- Direct Geminal Dimethylation of Ketones and Exhaustive Methylation of Carboxylic Acid Chlorides Using Dichlorodimethyltitanium
-
The reaction of ketones with an excess of (CH3)2TiCl2 (6) leads to the replacement of the carbonyl oxygen atom by two methyl groups.This mild method of direct geminal dimethylation involves Grignard-type addition followed by formation of tertiary carbocations which are captured by methyltitanium species.Additional functional groups such as primary alkyl chlorides, thioethers, aromatics, ethers and esters are tolerated, but not thioketals.The procedure has been applied to the synthesis of (+/-)-cuparene (44).Similarly, carboxylic acid chlorides are converted to tert-butyl derivatives.
- Reetz, Manfred T.,Westermann, Juergen,Kyung, Suk-Hun
-
p. 1050 - 1057
(2007/10/02)
-
- AN INEXPENSIVE INFLUENCE MODIFICATION OF THE SIMMONS-SMITH REACTION: THE FORMATION OF BROMOMETHYLZINC BROMIDE AS STUDIED BY NMR SPECTROSCOPY
-
Bromomethylzinc bromide, prepared from zinc metal and methylene bromide in tetrahydrofuran, gives moderate to good yields of cyclopropanation product when treated with olefins, thus providing an inexpensive alternative to the Simmons-Smith procedure.An NMR study of the reaction between metallic zinc and methylene bromide has been carried out: in addition to bromomethylzinc bromide and dimethylzinc, two further species were observed and tentatively identified as bis(bromomethyl)zinc a di- or tri-zinc compound.
- Fabisch, Bodo,Mitchell, Terence N.
-
p. 219 - 222
(2007/10/02)
-
- ORGANOMETALLIC REACTION MECHANISMS. XVIII. CONCERNING THE NATURE OF THE TRANSITION STATE IN THE REACTION OF TRIALKYLALUMINUM COMPOUNDS WITH KETONES
-
Et2AlCH2AlEt2 (1) has been used as a mechanistic probe to determine the nature of the transition state in the reaction of two equivalents of a trialkylaluminum compound with a ketone in hydrocarbon solvent. 1 was prepared in benzene and the solution composition determined.Low temperature 1H NMR data of 1 as the mono(diethyl etherate) indicate that the ether oxygen is simultaneously coordinated to both aluminum atoms.The reactions of 1 with 4-t-butylcyclohexanone in hydrocarbon solvent were compared to the reactions of triethylaluminium with the same ketone.The results support the importance of a bridging alkyl group described by the formation of a six-centered transition state when two equivalents of a trialkylaluminum compound are allowed to react with a ketone in hydrocarbon solvent.The results also argue against a transition state described by two moles of trialkylaluminum compound complexed to the carbonyl oxygen atom.
- Ashby, E. C.,Smith, R. Scott
-
-
- Modified Method of Synthesizing Dialkylzinc Compounds.
-
A convenient method of preparing dimethylzinc and diethylzinc has been devised. It consists in a reaction of a suitable alkyl iodide with a mixture Zn-Cu at a large laboratory scale. The applicability of easily accessible home reagents to the synthesis has been studied and the optimum reaction conditions have been established.
- Kuran,Rokicki
-
p. 347 - 348
(2007/12/09)
-
