Microwave Synthesis of SAPO‐11 and AlPO‐11: Aspects of Reactor Engineering

AlPO‐11 and SAPO‐11 are synthesized using microwave heating. The effects of precursor volume, reaction temperature, reactor geometry, stirring, applicator type and frequency on the microwave synthesis of SAPO‐11 and AlPO‐11 are studied. The nucleation time and crystallization rate are determined from crystallization curves for SAPO‐11 (and/or AlPO‐11), for the various parameters investigated. Increasing volume of the reacting material decreases the reaction rate of SAPO‐11 at 160°C. In particular, the nucleation time increases with increase in the reaction volume. Increasing the reaction temperature increases the crystallization rate and decreases the nucleation time, however it decreases the particle size. Nucleation of SAPO‐11 and AlPO‐11 under microwave heating is strongly dependant on the reaction temperature. Using wider geometry vessel (33 mm compared to 11 mm diameter) enhances the reaction rate, producing larger crystals in the same reaction time, even though the crystallization rate is decreased. The crystallization rate is enhanced by applicator type in the following order CEM MARS‐5 oven>CEM Discover “focused” system>monomode waveguide. Stirring the reacting solution during heating affects primarily the nucleation time. The effect of microwave frequency on the nucleation and growth of SAPO‐11 shows a dependence on the applicator type more than the specific frequency, for the frequency range 2.45–10.5 GHz. The difference between the crystallization rate observed at higher frequencies and that at 2.45 GHz maybe due to the multimode nature of the waveguide at frequencies above 2.45 GHz. Sweeping the microwave frequency linearly between 8.7 and 10.5 GHz at rates of 10 min^?1 and 100 min^?1 shows an intermediate crystallization curve to that for fixed frequencies of 2.45 GHz and that for 5.8, 8.7 and 10.5 GHz.     

Formation of Active Cyclic Five-membered Frustrated Phosphane/Borane Lewis Pairs and their Cycloaddition Reactions

The cyclic five-membered frustrated phosphane/borane Lewis pairs 11 a , b featuring the bulky octaethylhydrindacenyl- (Eind) substituent or its mono-bromo derivative (^BrEind) at phosphorus are monomeric at room temperature. The reactive frustrated Lewis pairs (FLPs) cleave dihydrogen. The cyclic FLP 11 b (^BrEind) undergoes 1,2-P/B addition to ethylene to give the zwitterionic heteronorbornane derivative 14 b . It reacts similarly with the carbon–carbon double bond of norbornene. With a variety of organic π-reagents, the cyclic FLP 11 b often undergoes reaction sequences reminiscent of the Alder–Rickert reaction: the cycloaddition reaction is followed by rapid cycloreversion to form new five-membered heterocyclic FLP products with extrusion of ethene. Reactions of 11 b with benzaldehyde or with acetylenes follow this reaction pattern.     

Cobalt(I)-mediated [2 + 2 + 2] cyclization of allenediynes toward a diastereoselective approach to 11-aryl steroid skeletons

[reaction: see text] An 11-aryl steroid skeleton has been built in one step with a simultaneous introduction of the substituents at both C11 and C10 in 48% overall yield from a trans-allenediyne, whereas a formal Alder ene reaction leading to a bicyclic yne-trienic compound becomes the major process from the cis-allenediyne.     

稀土Pr6O11上CO和表面羟基反应的原位FT-IR研究

利用FT-IR原位考察了稀土氧化镨上CO和表面羟基的反应。在473K以下,未检测到CO和氧化镨表面反应的吸附物种;在CO气氛中,升温到473K,观察到甲酸根吸附物种的红外特征峰1578,1371和1367cm~(-1)。用同位素D_2部分还原的氧化镨吸附CO以及甲酸吸附证实了CO与氧化镨表面的羟基反应可生成表面甲酸根吸附物种。讨论了CO在氧化镨表面的反应机理及甲酸根的氧化过程。     

LaNiAl11O19催化剂上甲烷与二氧化碳重整反应的研究

目前用于甲烷与二氧化碳重整反应研究的催化剂主要是负载镍及贵金属的催化剂，在较高的反应温度下，这类催化剂的载体和金属容易烧结，而且相互之间容易发生因相反应，从而导致催化剂失活[1.2]．因此，我们从高温稳定的载体材料人手，选择具有六铝酸盐结构的复合氧化物作为催化剂的基质材料，将镍离子镶嵌在复合氧化物特定的晶格位置上，一方面可提高镍离子的分散度和抗烧结能力，另一方面可以通过离子调变，改变催化剂表面酸碱性，提高催化剂抗积炭性能．实验结果表明，LaNiAl11O19不仅具有较高的甲烷与二氧化碳重整反应活性，而且镍离子…     

正庚烷与正十四烷在Pt/SAPO-11催化剂上临氢异构化

采用连续流动固定床反应装置，研究了0.6%Pt/SAPO-11催化剂上正庚烷与正十四烷的临氢异构转化。实验结果表明，在反应温度200 ℃～420 ℃，压力0.5 MPa，质量空速2.0 h－1的反应条件下，两种原料在高转化时均可保持90%以上的异构化选择性。在转化率小于55%时，C7与C14临氢异构所遵循的反应规律是一致的，即异构化和裂解的相对反应速率相同。依据产物分布组成随转化率变化的规律，提出了烷烃在Pt/SAPO-11催化剂上加氢转化的反应网络。同时，实验结果支持烷烃异构化反应在分子筛孔道内进行的观点。     

Syntheses of C2-labelled 11Z-retinals

To enable solid-state NMR investigations of the rhodopsin chromophore and its photointermediates, a series of 11Z-retinal isotopomers have been synthesised containing pairs of adjacent ¹³C labels at C9/C10, C10/C11 or C11/C12, respectively. The C9 labelled carbon atom was introduced through the Heck reaction of a ¹³C-labelled Weinreb acrylamide derivative, and the label at the C12 position derived from a ¹³C-containing ethoxy Bestmann-Ohira reagent. The ¹³C labels at C10 and C11 were introduced through the reaction of β-ionone with labelled triethyl phosphonoacetate.     

Diels-Alder reaction of maldoxin with an isopropenylallene

The Diels-Alder reaction of maldoxin with an isopropenylallene at 60-75 °C afforded an adduct closely related to chloropestolide A (24%) and a second adduct (0-11%) that underwent an ene reaction to generate the chloropupukeanolide D (11-22%) skeleton. The Diels-Alder reaction occurred with good selectively (>5:1) from a single face of maldoxin under much milder conditions than previously reported for the analogous dimethoxycyclohexadienone. Furthermore, the ene reaction took place under mild conditions, whereas the analogous Diels-Alder adduct from the dimethoxycyclohexadienone did not undergo an ene reaction.     

Novel synthesis of azepine derivatives via copper-mediated cyclization of 2-aza-hepta-2,4-dien-6-ynyl anions. Intramolecular addition of organocopper centers to the C-C triple bond

Deprotonation of alkynyl imines 1 with LDA at low temperature and subsequent transmetalation with copper thiophenolate gives the annulated azepines 11a-i in 41-73% yield after aqueous workup. The key step of the reaction is a copper-mediated intramolecular nucleophilic attack at the triple bond. [reaction: see text]     

HZSM-11分子筛的催化性能及酸性质的研究

用脉冲微反方法研究了不同温度下不同硅铝比的HZSM-11分子筛上邻二甲苯异构化活性和选择性。结果表明,硅铝比增加,二甲苯异构化活性变化不大。用TPD技术研究了不同硅铝比的HZSM-11的酸性质,测得了NH₂在HZSM-11上的程脱谱。结果表明,在HZSM-11表面上有两种强度的酸中心。硅铝比增加,弱酸中心数减少,强酸中心数基本不变。     

Kinetics Investigation of OH reaction with isoprene at 240-340 K and 1-3 torr using the relative rate/discharge flow/mass spectrometry technique

The kinetics of the reaction of OH radical with isoprene has been investigated at a total pressure of 1-3 Torr over a temperature range of 240-340 K using the relative rate/discharge flow/mass spectrometry (RR/DF/MS) technique. The reaction of isoprene with OH was found to be independent of pressure over the pressure range of 1-3 Torr at 298 K, and the reaction had reached its high-pressure limit at 1 Torr. However, the rate constant of this reaction is found to positively depend on pressure at 1-3 Torr and 340 K. At 298 K, the rate constant of this reaction was determined to be k1 = (10.4 +/- 1.9) x 10(-11) cm3 molecule(-1) s(-1), which is in good agreement with literature values. The Arrhenius expression for this reaction was determined to be k1 = (2.33 +/- 0.09) x 10(-11) exp[(444 +/- 27)/T] cm3 molecule(-1) s(-1) at 240-340 K. The atmospheric lifetime of isoprene was estimated to be 2.9 h based on the rate constant of isoprene + OH determined at 277 K in the present work.     

Reversible 1,3‐dipolar cycloaddition of dimethyl 2‐thiono‐1,3‐dithiole‐4,5‐dicarboxylate with dimethyl acetylenedicarboxylate

It was shown that dimethyl 2‐thiono‐1,3‐dithiole‐4,5‐dicarboxylate ( 2 ) and dimethyl acetylenedicarboxylate (DMAD) undergo a 1,3‐dipolar cycloaddition to produce a short‐lived ylide intermediate ( 3 ). The 1,3‐dipolar cycloaddition took place even at room temperature, although sluggishly, but took place much more rapidly under application of a high pressure of 500 MPa. The 1,3‐dipolar cycloaddition is reversible and the ylide 3 immediately splits into 2 and DMAD. When the reaction of 2 with DMAD was carried out at room temperature without solvent, a spiro‐1,3‐dithiole ( 11 ) was formed in 11% yield, whereas the reaction at 150°C provided a thiophene derivative ( 13 ) in 41% yield. It was found that 11 undergoes a thermal rearrangement to 13 . Results of attempted chemical trapping of the ylide 3 are also reported. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:434–440, 2000     

异丁烯直接胺化合成叔丁胺反应的热力学研究

叔丁胺是一种重要的有机化工中间体,广泛应用于制备橡胶促进剂,医药,农药,着色剂等诸多下游产物.目前,叔丁胺主要的生产方法,如叔丁脲水解法,异丁烯-氢氰酸法(Ritter法),卤代烃胺化法等存在产品收率较低,涉及强酸/强碱的使用,对设备腐蚀和环境污染严重等问题.异丁烯直接胺化生产叔丁胺,原子利用率100%,是典型的绿色化学反应.20世纪末,BASF公司以β沸石为催化剂,率先实现了异丁烯胺化技术的工业应用.但是,其反应条件苛刻,压力达28 MPa,生产过程能耗大,对设备材质要求高.目前,关于异丁烯直接胺化的文献较少,且相关研究多在远离工业应用的常压条件下进行.同时,对于异丁烯直接胺化反应过程的热力学,特别是缓和反应条件下的热力学尚待进一步系统和深入地研究分析,以期指导低温低压条件下高性能胺化催化剂的研发和工艺条件优化.我们计算了473?573 K间,异丁烯胺化制备叔丁胺反应的ΔrH,ΔrG,Kp等热力学数据.在此基础上,分析了反应温度,压力和氨烯比(摩尔比)对异丁烯平衡转化率(叔丁胺选择性>99%,未予考虑)的影响.结果表明,异丁烯胺化是中等强度的放热反应,升高反应温度会急剧降低异丁烯的平衡转化率,如在5 MPa,氨烯比1的条件下,反应温度从473 K提高到573 K,异丁烯平衡转化率从40.6%降到6.9%.但从动力学角度而言,升温可提高胺化反应速率,因此在特定的反应条件下和催化剂上,必然存在最佳反应温度.提高反应压力和氨烯比有利于提高异丁烯的热力学平衡转化率.开发在低温和相对较低的压力下具有较高胺化活性的催化剂是提高该过程经济性和实用性的关键.在较缓和的反应条件下(523 K,5 MPa,氨烯比4及异丁烯空速0.5 h?1),考察了ZSM-5(R=50和R=412,R为硅铝比,下同),ZSM-11(R=48),MOR(R=10),SAPO-11(摩尔组成,1.6Al2O3:1.0SiO2:1.4P2O5)等不同拓扑结构分子筛以及氧化铝在异丁烯胺化反应中的性能.结果表明,空白试验中,无叔丁胺产物生成.在ZSM-11上的获得最高的异丁烯胺化转化率,为14.2%(达到平衡转化率的52.2%),在ZSM-5(R=50),ZSM-5(R=412)和MOR上,异丁烯转化率分别为13.9%,6.4%和2.9%,叔丁胺选择性均大于99.8%.而SAPO-11和氧化铝未呈现出胺化反应活性.关联氨气程序升温脱附,吡啶吸附红外表征结果及分子筛孔结构特点,表明分子筛胺化活性与其孔径及Br?nsted酸的酸量和酸强度密切相关.为了进一步验证实际反应体系中反应条件对异丁烯胺化反应过程的影响规律,我们在ZSM-11催化剂上,系统考察了反应温度,压力,氨烯比和异丁烯空速对催化剂胺化反应性能的影响及变化规律.结果表明,在其他条件不变的情况下,异丁烯转化率随着温度的升高呈现出先增大后减小的趋势.适当提高原料中氨烯比和反应压力,以及采用较低异丁烯空速有利于促进异丁烯的转化.上述规律与热力学计算结果呈现出较好的一致性.在ZSM-11催化剂上,异丁烯直接胺化反应的较佳反应条件为523 K,5 MPa,氨烯比4,异丁烯空速0.5 h?1.上述结果可为异丁烯直接胺化合成叔丁胺过程新型高效催化剂的研发和反应工艺条件优化提供参考和指导.     

Updated investigation of the reaction between copper and naphthol blue black b and determination of trace amounts of copper in water

The biological dye, naphthol blue black B (NBBB) was found to produce a sensitive reaction with copper(II) at pH over 7. This reaction was very interesting. The complexation of Cu(II) with NBBB happened at pH between 6 and 11 but the redox catalytic reaction happened at pH over 11, where copper(II) served as a catalyst. In this study, ordinary spectrophotometry was limited for use because of the serious interference of excess reactant. A new method, Β-correction principle, was applied because it can eliminate the above interference. This method can give the simple determination of properties of Cu-NBBB complex solution at pH 9.5, which involved the complex ratio, real molar absorptivity, and stability constant (K). Results showed that the formed Cu-NBBB complex occurred as Cu(NBBB) at pH 9.5, its real rather than apparent absorptivity was equal to 7.62 x 10³ L mol^-1 cm^-1 at 630 nm, and its stability constant was 1.32 x 10⁶. The redox catalytic reaction between Cu(II) and NBBB at pH 13 was used to determine trace amounts of copper in water. This reaction was very sensitive and highly selective. Most of the metals did not interfere with the direct determination of copper. The detection limit of copper was 0.002 mg/L, and the recovery was between 90 and 104% with the relative standard deviation of less than 11%. This article was submitted by the author in English.     

Synthesis of 10,11-dihydroleukotriene B(4) metabolites via a nickel-catalyzed coupling reaction of cis-bromides and trans-alkenyl borates

Synthesis of 10,11-dihydro-, 10,11,14,15-tetrahydro-, and 10, 11-dihydro-12-oxoleukotriene B(4) compounds (2, 4, 5) was accomplished stereoselectively by using the nickel-catalyzed coupling reaction illustrated in Scheme 1. The C(1)-C(7) fragments, TBS ether 10a for 2 and 4 and ethyoxyethyl (EE) ether 10b for 5, were prepared in enantiomerically pure forms (>99% ee) by a modified literature procedure (ref 11a). On the other hand, boronate esters 11a and 11b, which correspond to the C(8)-C(20) parts of 2 and 4, respectively, were synthesized from (R)-epichlorohydrin (18) of 99% ee. Briefly, 18 was converted into acetylenes 24 and 32 through epoxide ring-opening with LiC triple bond CC(5)H(11)/BF(3).OEt(2) or C(7)H(15)MgBr/CuCN. Hydroboration of these acetylenes with (+)-(Ipc)(2)BH followed by reaction with MeCHO afforded the corresponding diethyl boronates, which upon ligand exchange with Me(2)C(CH(2)OH)(2) furnished boronate esters 11a and 11b in 75% and 77% yields, respectively. In a similar manner, racemic boronate ester rac-11a, an intermediate for synthesis of 5, was prepared from racemic epichlorohydrin. For synthesis of 2, borate 25 was generated from 11a (1.5 equiv) and MeLi (1.6 equiv). Without isolation, 25 was submitted to reaction with 10a (1 equiv) in the presence of a Ni(0) species at room temperature overnight to afford 26, which upon treatment with TBAF furnished 2 in 64% yield from 10a. Similarly, 11b and 10a furnished 4 in good yield. To synthesize 5, rac-11a and EE ether 10b were joined by the coupling reaction to produce 39, which was transformed into 40 by desilylation with TBAF. After hydrolysis of 40, oxidation with PDC followed by deprotection of the EE group furnished 5 in 36% yield from 40. In addition, 2 was converted into amide 3 in 92% yield.     

Preparation of N-[11C]methyl-2,5-dimethoxy-4-bromo-amphetamine

For in vivo receptor studies N-[¹¹C]methyl-2,5-dimethoxy-4-bromo-amphetamine, [¹¹C]MDOB, was synthesized by the reaction of [¹¹C]CH₃I with DOB in acetonitrile. The labelling yield was determined in dependence on amount of precursor, time and temperature of the methylation reaction. During 10 to 15 minutes 60% to 70% of [¹¹C]MDOB has been obtained at 110°C.     

Synthesis of 11C-labelled N,N'-diphenylurea and ethyl phenylcarbamate by a rhodium-promoted carbonylation via [11C]isocyanatobenzene using phenyl azide and [11C]carbon monoxide

The reaction with phenyl azide and [11C]carbon monoxide to give N,N'-diphenyl[11C]urea and ethyl phenyl[11C]carbamate has been studied with the aim of development of a new methodology for carbonylation using [11C]carbon monoxide with high specific radioactivity. The synthesis of 11C-labelled N,N'-diphenylurea from phenyl azide and [11C]carbon monoxide, with 1,2-bis(diphenylphosphino)ethane-bound Rh(I) complex at 120 degrees C at a pressure of 35 MPa in the presence of aniline was accomplished in 82% trapping efficiency and 82% conversion yield. This approach was also useful for the synthesis of ethyl phenyl[11C]carbamate with lithium ethoxide as a nucleophilic reagent giving 90% trapping efficiency and 76% conversion yield. These reactions can be considered to proceed via a [11C]isocyanate or a [11C]isocyanate-coordinated Rh complex to give the corresponding 11C-products. This protocol provides the chemical basis for the synthesis of [11C]urea and [11C]carbamate derived from [11C]isocyanates.     

Kupfer(II)-chlorid-katalysierte ‘Carben-Dimerisierung’ von 1-Halogeno-1-Lithiocyclopropanen: Ein einfacher Zugang zu Bi(cyclopropylidenen)

Copper(II)-Chloride Catalyzed ‘Carbene Dimerization’ of 1-Halogeno-1-lithiocyclopropanes: A Simple Access to Bi(cyclopropylidenes) A series of 13 bi(cyclopropylidenes) 11 are prepared in a simple one-pot reaction by halogeno-lithio exchange between 1,1-dibromocyclopropanes 1a – n and BuLi, in most cases at ?95°, to give 1-bromo-1-lithiocyclopropanes 2a – n , followed by treatment with CuCl₂ at low temperature and a simple workup at room temperature (Scheme 3c and Table 1). The yields of bi(cyclopropylidenes) 11 strongly depend on reaction parameters, as explicitly shown for the conversion 1f →→ 11f (Tables 2–8). Mixed couplings between two different carbenoids are possible (Scheme 4), while diastereoselectivity of the active transition-metal complex seems to be low. The structures of bi(cyclopropylidenes) 11 are confirmed by spectroscopic data as well as by X-ray analysis of an isolated crystalline diastereoisomer of 11k (Fig. 1).     

A new conjugated addition of trialkyl phosphites and alkylidenephosphoranes to 3‐ω‐azideoacetyl coumarin synthesis of some 1,2,3,4‐triazaphospholes,triazoles, and azido‐coumarin derivatives

A new and efficient conjugate addition of trimethyl and triethyl phosphites to 3‐ω‐azidoacetylcoumarin ( 1 ) has been studied. The reaction proceeded smoothly at r.t. furnishing 1,2,3,4‐triazaphosphole coumarin derivatives 4a , 4b in ～75% yields. Linear substituted triazoles 10b , 11a were also obtained from the reactions of 1 with α‐keto ylides, acetyl‐ and benzoylmethylene triphenylphosphoranes. Contrary to these results, Wittig reaction was occurred when 1 was allowed to react with α‐alkoxycarbonylmethylene‐ and cyanomethylenetriphenylphosphoranes 7c , 7d , 7e as well as with methylidene‐ and benzylidenetriphenylphosphoranes 8b , 10a resulting in the formation of the corresponding olefins either as an intermediate 14b or as final products 11b , 11c , 12a . J. Heterocyclic Chem., (2011).     

Synthesis and Antimicrobial Activity of Some Novel Substituted Bis‐Pyridone,Pyrazole, and Thiazole Derivatives

A variety of novel bis‐heterocyclic derivatives were synthesized via the reaction of bis‐cyanoacetanilide derivative 3 with various aromatic aldehydes (1:2 molar ratio), to give the corresponding bis‐arylidene derivatives 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l , 5m . On the other hand, reacting compound 3 with substituted 2‐hydroxybenzaldehydes 6a , 6b , 6c afforded 2‐iminochromene‐3‐carboxamides 7a , 7b , 7c . The reaction of compound 5 with malononitrile afforded the novel bis‐pyridones 9a , 9b , 9c , 9f , 9g , 9h . The reaction of 5 with hydrazine derivatives afforded pyrazoles 11a , 11b , 11c , 11d , 11e , 11f , respectively. Compound 3 reacts with phenyl isothiocyanate in the presence of potassium hydroxide at room temperature followed by addition of some different halo‐carbonyl compounds to afford bis‐poly‐functionalized thiazole derivatives 13a , 13b , 13c . The bis‐enamine derivative 15 reacts also with hydrazine hydrate, guanidine, and hydroxylamine to give bis‐pyrazole 17 , pyrimidine 19 , and isoxazole 21 derivatives, respectively. Some of the newly synthesized compounds show moderate to high antimicrobial activity.