4-苯硫基苯甲醛的合成

以对溴苯甲醛和苯硫酚为起始原料、碳酸钾和碘化铜为取代反应催化剂,合成了4-苯硫基苯甲醛。用正交实验法优化了合成反应条件:原料配比n(对溴苯甲醛)∶n(苯硫酚)=1.00∶1.03,反应温度110℃,反应时间6 h,在优化条件下合成4-苯硫基苯甲醛,总收率达到85.2%。目标化合物结构分别经IR分析、元素分析和熔点测定等表征。     

对硝基苯甲醛-d5的合成

以苯-d6为原料,经过溴代、硝基化、氰基化、水解、还原与氧化等六步反应,高效合成了对硝基苯甲醛-d5,对关键步骤氰基化反应的条件进行了优化。对硝基苯甲醛-d5的结构经13 CNMR、IR与MS表征,总收率为24%(以苯-d6计),化学纯度为99.1%,同位素丰度为98.2%。     

苯甲醇氧化制苯甲醛反应的研究进展

苯甲醛是最简单也是工业上最重要的芳香醛,在医药、染料、香料、树脂等行业有着广泛的应用。由于目前国内工业化生产的苯甲醛内含有氯化物,严重地限制了苯甲醛在医药和食品行业中的应用,因此开发一种无氯的绿色苯甲醛生产工艺迫在眉睫。而苯甲醇直接氧化制备苯甲醛就是这样一种绿色的工艺。苯甲醇直接氧化制备苯甲醛的方法可以分为苯甲醇气相氧化法和苯甲醇液相氧化法,由于各自突出的优点在近几年得到了广泛的研究。本文主要结合国内外苯甲醇氧化制苯甲醛反应的研究进展进行了简单的介绍。     

苯甲醇选择氧化制苯甲醛研究进展

苯甲醛是一种重要的精细化学品。苯甲醇选择氧化制苯甲醛是近年来受到重视的绿色苯甲醛生产过程,环境友好且可以得到高品质产品。因此,本文从催化剂,以及溶剂、促进剂等工艺条件等方面讨论了这一多相催化氧化过程研究进展,分析了贵金属催化剂、非贵金属催化剂、金属活性组分之间的协同作用、有机溶剂、无机溶剂、碱性促进剂等因素对苯甲醇选择氧化过程的影响,为开发高效的苯甲醇选择氧化制苯甲醛催化剂提供参考。     

邻硝基苯甲醛合成新技术

本文提出了以邻硝基甲苯(ONT)为起始原料,在光照条件下经溴化氢和双氧水溴化成邻硝基二溴甲基苯(ONDB),再用浓硫酸水解制得邻硝基苯甲醛(ONBA)的新路线.用元素分析、红外光谱及氢核磁共振谱分析证实了产物ONDB及ONBA的结构.溴化收率为90%,水解收率为57.6%,总收率51.8%,比现有工业生产方法的收率都高得多.     

对溴苯甲醛合成新工艺

用三氧化二锰直接氧化法将对溴甲苯氧化对溴苯甲醛,讨论了合成过程中影响产率的各种因素,确定反应的优化条件为温度338K,硫酸的浓度7.5mol/L,三氧化二锰1.8g,产率可达73.89%。并对不同硫酸浓度下Mn3+氧化对溴甲苯的反应动力学进行了研究。该方法具有工艺简单,条件温和,对环境不造成污染,易于工业化生产等优点。     

两步法合成间硝基苯甲醛

间硝基甲苯与双氧水、氢溴酸在AIBN作用下,生成间硝基一溴苄和二溴苄,再经DMSO、二甲胺氧化水解生成间硝基苯甲醛。研究了溴化、氧化水解反应的影响因素,优化了反应条件。结果表明,溴化反应较佳的条件为:溴化温度60℃,溴化时间4 h,n(间硝基甲苯)∶n(氢溴酸)∶n(双氧水)=1∶2.5∶2.5,AIBN用量0.8 g;氧化水解反应较佳的条件为:氧化温度105℃,保温时间8 h,水解温度60℃,水解时间1 h。在该条件下,间硝基苯甲醛收率达58.6%,色谱纯度达99.1%。通过IR和1HNMR对产物结构进行了表征。     

邻硝基苯甲醛合成新技术

本文提出了以邻硝基甲苯（ONT）为起始原料,在光照条件下经溴化氢和双氧水溴化成邻硝基二溴甲基苯（ONDB）,再用沈硫酸水解制得邻 基苯甲醛（ONBA）的新路线。用元素分析、红外光谱及氢核磁共振谱分析证实了产物ONDB及ONBA的结构。溴化收率为90％,水解收率为57．6％,总收率51．8％,比现有工业生产方法的收率都高得多。     

间接电氧化合成对溴苯甲醛

提出采用间接电合成法以Ce4+/Ce3+为媒质,在高剪切混合乳化机搅拌下使Ce4+氧化对溴甲苯合成对溴苯甲醛工艺,使用后的媒质再生循环使用,无三废排放。在隔膜电解槽中Ce3+电氧化的最佳条件是c(Ce3+)=0 8mol/L;c(H2SO4)=0 3mol/L;电流密度200A/m2;电量1 0F/mol,Ce4+的电解收率90 9%。槽外合成对溴苯甲醛的最佳条件是n(Ce4+)∶n(p Br—C6H4—CH3)=4∶1;c(H2SO4)=0 3mol/L;反应温度85℃,对溴苯甲醛反应收率78 5%,Ag+催化下对溴苯甲醛反应收率90 3%。     

对溴苯甲醛合成过程中影响因素研究

本文以二苄醚、Br₂为主要原料,经加Br₂、HNO₃氧化两步反应得到对溴苯甲醛,通过单因素变量实验验证了反应温度、反应时间、原料配比以及催化剂用量对对溴苯甲醛收率的影响,提出了最佳反应控制条件：反应器内温度为50℃,反应时间为8h,原料中Br₂与二苄醚物质的量之比为2.2∶1,催化剂Fe最佳用量为0.5g·L^-1,在该组合条件下对溴苯甲醛收率为77.2%。研究结论可为进一步揭示对溴苯甲醛生成机制提供理论参考。     

酯-二苯酮光化夺氢反应活泼自由基的ESR研究

自旋捕捉技术与ESR相结合,为检测反应过程中产生的自由基活泼中间体提供一个方便且有效的方法。近年来,国内外研究工作者利用这一方法,对固相,液相和气相中产生的活泼自由基已进行了广泛的研究。特别是对二苯酮与质子给体如:醇、胺、     

煤气CO和H2高电压放电反应机理研究

本文研究了ＣＯ和Ｈ_２的高电压放电反应机理，发现ＣＯ和Ｈ_２的放电化学反应是自由基反应，在高电压放电条件下，电子与ＣＯ和Ｈ_２分子碰撞激发生成自由基，发生化学反应；在低输入电压范围内，电场加速低能电子成为高能电子的过程为反应控制步骤。     

Reduction electrochimique a l'electrode de mercure de composes α-hydroxycarbonyles en solution aqueuse α — I. Glyoxals RCOCH(OH)2

Reduction at the mercury electrode in aqueous solution of the unhydrated form of glyoxals exhibits evidence of a reversible system: RCOCHO + 2e + 2H⁺ ?har2; RC(OH)CHOH with RCH₃ or C₆H₅.For the hydrated form C₆H₅COCH(OH)₂, investigation indicated occurrence of two types of irreversible processes. In neutral media transfer of two electrons involve either the hydrogenolysis of the COH bond, yielding hydroxyacétophenone: C₆H₅COCH₂OH, or alternatively the reduction of the keto grouping yielding mandelaldehyde: C₆H₅CHOHCHO.The COH cleavage is exclusive in acidic media and for aliphatic glyoxals RCOCH(OH)₂.     

Radiation Chemistry of Ethylene Glycol,Meso-Erythritol, 2-Deoxy-D-Ribose and Alkyl Phosphates as DNA Model Compounds

The γ-radiolysis of ethylene glycol, meso-erythritol, 2-deoxy-ribose, and alkyl phosphates has been studied in diluted (10^?2 M), N₂ O-saturated, deoxygenated aqueous solutions. Products and their G values have been determined. Reaction schemes were derived from complete material balances. In the polyols the primary attack of the radiolytically formed OH radicals and H atoms leads to α, β-dihydroxyalkyl radicals (A) which eliminate water to give substituted α-carbonyl-methyl radicals: (B) Disproportionation reactions of the radicals A and B yield products having the structural units ? CO? CHOH? and ? CO? CH₂ —. In ethylene glycol a chain reaction is induced, radical B abstracts a hydrogen from ethylene glycol to give acetaldehyde and radical A. In 2-deoxy-ribose the major attack is at C-1. Products from this radical are 2-deoxy-ribonic acid and 2,5-dideoxy-ribonic acid. In the formation of the latter a rearrangement is involved. With trimethyl phosphate, the reaction of the solvated electron is only small (2 × 10^s 1/mole sec), as shown by pulse radiolysis. Dimethyl and methyl phosphates do not react with the solvated electron to a measurable extent. The attack of the OH radical apparently leads to a cleavage of the alkyl phosphate linkage.     

7种茶氨酸类似物的合成及清除自由基活性

以L-谷氨酸为起始原料,经邻苯二甲酸酐保护、酰化开环、肼解脱保护等反应合成了7种茶氨酸类似物,结构经EA、IR、1HNMR、13CNMR和MS进行了确认,并测定了其清除DPPH自由基和羟自由基活性。结果表明:2-氨基-5-氧代-5-[(4-羟基苯基)氨基]戊酸清除自由基活性最强,0.002 mol/L时清除DPPH自由基率为90%,0.004 mol/L时清除羟自由基率达95%;2-氨基-5-氧代-5-[(4-氨基苯基)氨基]戊酸次之。由此可见,茶氨酸类似物中5位连有苯基或所连苯基对位有供电子基团时,可提高其清除DPPH自由基和羟自由基活性,且随对位所连基团供电性的提高,清除活性增强。     

褐煤燃烧阶段风量对指标气体的影响

以平庄瑞安褐煤为研究对象,通过热重试验确定褐煤燃烧阶段温度范围,利用管式炉程序升温系统进行煤样氧化自燃试验,得到风量分别为40、80、120、160和200 m L/min条件下的气体;为确定优选指标气体的关联度大小,采用灰色关联法对其进行分析。结果表明:褐煤燃烧阶段温度为247~433℃,408℃左右达到快速燃烧状态。当风量恒定时,CO_2/ΔO_2、CO/ΔO_2、C_2H-4与温度的关联度比CO、C_2H_6、C_2H_4/C_2H_6高。随风量不断增加,指标气体与温度的关联度:CO_2/ΔO_2最大,其次是CO/ΔO_2、C_2H_4和CO,C_2H_6和C_2H_4/C_2H_6最小。故可将CO_2/ΔO_2、CO/ΔO_2和C_2H_4作为主要指标,CO作为辅助指标用于预测煤矿井下封闭火区燃烧状态。     

The reaction of hydroxyl radicals with carbon at 298 K

The reaction of free OH radicals with graphite was studied in a flow system by mass spectrometry, the OH being produced by the reaction H + NO₂ → OH + NO. The OH radicals react rapidly at 298 K to produce approximately equal amounts of CO and CO₂. The collision efficiency (γ) for gasification of the carbon is>5 × 10^?3. OH radicals are much more reactive than free oxygen atoms towards graphite at 298 K. Carbon is an efficient heterogeneous catalyst for the reaction H + OH → H₂O, and when free hydrogen atoms are present, this reaction is several times faster than the gasification of the carbon by OH. Carbon is also an efficient catalyst for the recombination of H atoms: 2H → H₂.     

费托合成体系气体-高碳烷烃的相平衡计算

选取Peng-Robinson(PR)方程与perturbed-chain SAFT(PC-SAFT)方程,采用单流体混合规则,重点考察了在费托合成工艺条件下的小分子气体(CO,H2,CO2,N2,CH4和C2H6)与高碳烷烃(C20,C28和C36)体系的气液相平衡.结果发现,在对不同碳数高碳烷烃溶剂采用单一交互作用参数时,PC-SAFT与PR方程计算的液相浓度与实验值的总平均偏差分别为1.39%与1.98%.而不考虑交互作用参数时,其误差分别为25.18%与16.195%.对各系统的交互作用参数进行了研究,结果表明,随温度和烷烃碳数的升高,PC-SAFT方程的交互作用参数缓慢升高,而PR方程的交互作用参数则下降,且幅度较大.因此,考虑交互作用参数时,PC-SAFT方程具有更好的计算精度和可外推性.     

Mechanism of methanol decomposition on the Pd/WC(0001) surface unveiled by first-principles calculations

In this study, the decomposition of methanol into the CO and H species on the Pd/tungsten carbide (WC)(0001) surface is systematically investigated using periodic density functional theory (DFT) calculations. The possible reaction pathways and intermediates are determined. The results reveal that saturated molecules, i.e., methanol and formaldehyde, adsorb weakly on the Pd/ WC(0001) surface. Both CO and H prefer three-fold sites, with adsorption energies of −1.51 and −2.67 eV, respectively. On the other hand, CH₃O stably binds at three-fold and bridge sites, with an adsorption energy of −2.58 eV. However, most of the other intermediates tend to adsorb to the surface with the carbon and oxygen atoms in their sp³ and hydroxyl-like configurations, respectively. Hence, the C atom of CH₂OH preferentially attaches to the top sites, CHOH and CH₂O adsorb at the bridge sites, while COH and CHO occupy the three-fold sites. The DFT calculations indicate that the rupture of the initial C–H bond promotes the decomposition of CH₃OH and CH₂OH, whereas in the case of CHOH, O–H bond scission is favored over the C–H bond rupture. Thus, the most probable methanol decomposition pathway on the Pd/WC(0001) surface is CH₃OH → CH₂OH → trans-CHOH → CHO → CO. The present study demonstrates that the synergistic effect of WC (as carrier) and Pd (as catalyst) alters the CH₃OH decomposition pathway and reduces the noble metal utilization.     

Electron spin resonance studies of γ-irradiated cellulose. I. Free radicals in decrystallized cellulose

The types of free radicals formed in decrystallized cellulose prepared from cellulose I and II after γ-irradiation in nitrogen atmosphere at room temperature were studied by ESR spectroscopy. X-Ray diffraction revealed that decrystallized cellulose I and II have the same microstructure. The ESR spectra obtained with the γ-irradiated decrystallized samples are simple. By contacting the irradiated sample with moisture in nitrogen atmosphere, the ESR spectrum changed to a narrow singlet, which gradually decreased in intensity until the spectrum completely disappeared. It was found that the types of free radicals generated in the decrystallized cellulose by γ-irradiation consist of the overlap of singlet and doublet. The singlet spectrum is mainly attributed to alkoxyl radical formed by the rupture of glycosidic linkage at the C 1 or C 4 position, and the doublet spectrum is ascribed to radical formed by hydrogen abstraction from the C 1 position in cellulose molecule.