Ionic liquid-assisted preparation of hydroxyapatite and its catalytic performance for decarboxylation of itaconic acid

The synthesis of methacrylic acid from biomass-derived itaconic acid is a green route,for it can get rid of the dependence on fossil resource.In order to solve the problems on this route such as use of a preciousmetal catalyst and a corrosive homogeneous alkali,we prepared a series of hydroxyapatite catalysts by an ionic liquid-assisted hydrothermal method and evaluated their catalytic performance.The results showed that the ionic liquid[Bmim]BF_(4) can affect the crystal growth of hydroxyapatite,provide fluoride ion for fluorination of hydroxyapatite,and adjust the surface acidity and basicity,morphology,textural properties,crystallinity,and composition of hydroxyapatite.The[Bmim]BF4 dosage and hydrothermal temperature can affect the fluoride ion concentration in the hydrothermal system,thus changing the degree of fluoridation of hydroxyapatite.High fluoride-ion concentration can lead to the formation of CaF_(2) and thus significantly decrease the catalytic performance of hydroxyapatite.The hydrothermal time mainly affects the growth of hydroxyapatite crystals on the c axis,leading to different catalytic performance.The suitable conditions for the preparation of this fluoridized hydroxyapatite are as follows:a mass ratio of[Bmim]BF4 to calcium salt=0.2:1,a hydrothermal time of 12 h,and a hydrothermal temperature of 130℃.A maximal methacrylic acid yield of 54.7%was obtained using the fluoridized hydroxyapatite under relatively mild reaction conditions(250℃ and 2 MPa of N_(2))in the absence of a precious-metal catalyst and a corrosive homogeneous alkali.

Influence of Ca/P ratio on the catalytic performance of hydroxyapatite for decarboxylation of itaconic acid to methacrylic acid

Methacrylic acid,an important organic chemical,is commercially manufactured starting from fossil feedstock.The decarboxylation of itaconic acid derived for biomass is a green route to the synthesis of methacrylic acid.In view of the problems existing in the researches on this route such as use of noble metal catalyst,harsh reaction conditions and low desired-product yield,we prepared a series of hydroxyapatite catalysts with different Ca/P molar ratios and evaluated their catalytic performance.The results showed that the hydroxyapatite catalyst with a Ca/P molar ratio of 1.58 had the best catalytic activity.The highest yield of MAA up to 61.2%was achieved with basically complete conversion of itaconic acid under the suitable reaction conditions of 1 equivalent of NaOH,2 MPa of N_(2),250℃,and 2 h.On this basis,a reaction network for the decarboxylation of itaconic acid to methacrylic acid catalyzed by hydroxyapatite was established.With the aid of catalyst characterization using X-ray powder diffraction,NH3/CO2 temperature-programmed desorption,N_(2)physisorption,inductively coupled plasma optical emission spectrometry,and scanning electron microscopy,we found that the distribution of surface acid sites and basic sites,crystal growth orientation,texture properties and morphology of hydroxyapatite varied with the Ca/P molar ratio.Furthermore,the change of the crystal growth orientation and its influence on the surface acidity and alkalinity were clarified.

The Oxidative Decarboxylation of Nitrilotriacetic Acid (NTA)——A Study of the Reaction of NTA with Cerium(Ⅳ) in HCIO_4

The reaction between Ce (IV ) and NTA was investigated titrimetrically and spectrophotometrically. Two equivalents of Ce( IV ) are reduced per mole of NTA almost instantaneously at room temperature. With increasing reaction time an ultimate of about 7 equivalents of Ce( IV) is consumed per mole of NTA at room temperature. Carbon dioxide, formaldehyde and dimethylamine are the major and readily detectable products of oxidation of NTA by Ce( IV ). The rates of the reaction in HClO4 were measured spectrophotometricaUy using the stopped flow technique. The effects of both acidity of the medium and added salts support and extend preliminary results.

How Effective Is the Single-point Energy Calculation in Investigating the Reaction Mechanisms?New Decarboxylation Mechanism of Pyrrole-2-carboxylic Acid by Full Optimization with CPCM Solvation Model

The decarboxylation of pyrrole-2-carboxylic acid in acid solutions was elucidated by full optimization with the CPCM solvation model at the B3LYP/6-31 l＋＋G（d,p） level. Compared with the single-point energy calculation, CPCM full optimization is better to model solvent environments to gain reasonable reaction mechanisms. The π interactions play a significant role in the decarboxylation of pyrrole-2-carboxylic acid （R）. Firstly, the a hydrogen is protonated, but all of the carbonyl hydration pathways bear relatively higher energy barriers. The carbonyl group can rove over the pyrrole ring, but it does not lead to the speciation of pyrrole and protonated carbon dioxide for the latter is an energy-rich species. The decarboxylation mechanism proposed here is that, the protonated pyrrole-2-carboxylic acid （RH） decarboxylates via direct C-C bond cleavage with the aid of a water molecule to accommodate the proton on the carbonyl group.

Sm/TiCl_4 (cat.) system-mediated intermolecular and intramolecular reductive coupling reactions of ketones with esters

Sm/TiCl4 system could well integrate the high reactivity of samarium(II) and high deoxygenation capacity of low valent titanium within one system. In this paper, the intermolecular and intramolecular reductive coupling reactions of ketones with esters mediated by metallic samarium (Sm) and a catalytic amount of titanium tetrachloride (TiCl4) were successfully de- veloped. A series of substituted ketones and cyclic β-keto-esters were prepared in moderate to good yields under reflux and neutral conditions.

Efficient Cross-Coupling Reaction of Aryltrifluoroborates and Aroyl Chlorides for the Synthesis of Fluorine Substituted Aromatic Ketones

The direct aroylation of ArCOPdCl with potassium aryltrifluoroborates establishes a new cross-coupling synthetic tool for the synthesis of various fluorine substituted benzophenones. The new microwave irradiated process is very efficient and produce high yield benzophenone products within minutes.

LOW-VALENT TITANIUM INDUCED REDUCTIVE CROSS-COUPLING REACTION OF ESTERS WITH DIARYL KETONES

The intermotecular coupling reaction of esters with diarvl ketones induced by titanium tetrachtoride and zinc powder was studied.

LOW-VALENT TITANIUM INDUCED REDUCTIVE CROSS-COUPLING REACTION OF ACYL CHLORIDES WITH DIARYL KETONES

Treatment of acyl chlorides and diaryl ketones with an activated Ti(o)reagent,prepared by reduction of TiCl_4 with Zn powder,effects an intermolecular reductive cross-coupling reaction leading to ketones.

Mechanochemical Reaction of Aromatic Ketones and Aldehydes in the Presence of Zn-ZnCl_2

The solvent-free reactions of aromatic ketones and aldehydes in the presence of Zn-ZnCl2 were performed with the aid of high-speed vibration mill, Retsch MM200 mixer mill and Retsch RM100 mortar grinder to give pinacol coupling and reduction products in varying yields.

离子液体中PMBA脱羧反应及界面水影响的电化学SERS研究

基于气-液界面自组装法和转移技术制备了负载Au纳米粒子单层膜的玻碳电极(Au MLF@GC),并将其用于离子液体-电化学体系界面过程现场的研究.以对巯基苯甲酸(PMBA)的表面等离激元共振(SPR)催化脱羧生成苯硫酚(TP)反应为探针,采用电化学-表面增强拉曼光谱(SERS)技术,通过电位阶跃法研究了其在离子液体体系中的反应动力学行为.结果表明,亲水性离子液体[BMIm]BF_(4)/Au MLF@GC的零电荷电位(pzc)为−0.95 V,PMBA脱羧反应仅在pzc以正区间发生;通过SERS谱峰强度变化以二级反应拟合获得该反应的速率常数,发现其反应速率常数的对数与阶跃后电位呈线性关系;随着体系外加水的含量(摩尔分数)由0增至0.001和0.003,阶跃后发生脱羧反应的起始电位负移,且同一阶跃电位下反应速率常数随着外加水量的增加而增大.

金催化联烯胺与烯基叠氮的加成反应构建α-烯丙基酮化合物

烯基叠氮是一类重要的有机合成中间体,被广泛应用于含氮杂环化合物的合成中,但将其应用于联烯胺的加成反应少见报道.利用金催化活化联烯胺形成的烯丙基正离子中间体与烯丙基叠氮化合物发生加成反应,进一步发生水解得到9个α-烯丙基酮衍生物,所得产物均通过红外、核磁共振以及高分辨质谱进行确认,其中,对化合物3i进行了X-单晶衍射,确定了其结构.该反应利用烯基叠氮作为亲核试剂,实现了联烯胺与其加成反应,丰富了联烯胺的反应类型.

聚亚胺醚亚胺酮的合成及性能研究

文章以4,4’-二溴对苯甲酮和4,4’-二氨基二苯醚为单体,三(二苄基丙酮)二钯为催化剂,通过Buchwald-Hartwig芳胺化反应,实现CAr-N偶联反应,合成了新型功能高分子聚亚胺醚亚胺酮。实现芳香二胺结构单元和二溴化芳香酮结构单元的共聚,对共聚物结构、基本性能进行表征,并研究CAr-N偶联构建对苯甲酮/芳基醚主链结构的可行性,探讨聚合物主链构型、热稳定性和其他性能等。

Synthesis of Diverse Oxetane Amino Acids via Visible-Light-Induced Photocatalytic Decarboxylative Giese-Type Reaction

The divergent synthesis of versatile 3,3′-disubstituted oxetane amino acids by utilizing visible-light-induced photocatalytic decarboxylative Giese-type reaction has been demonstrated.3-Methyleneoxetane-derived substrates are readily available in a single-step and highly reactive as radical acceptors,allowing the production of versatile oxetaneγ-andα-amino acids in high yields.A distinct ring strain release-driven radical addition mechanism was preliminarily revealed.The preparative power was further highlighted by the application in the synthesis of oxetane-containing dipeptides and azetidine amino acids,as well as the transformation of the product into novel oxetane-containing spiro-heterocycle pharmacophore.

间苯三酚联合维生素B6治疗妊娠剧吐的效果观察

目的分析间苯三酚联合维生素B6治疗妊娠剧吐的效果。方法通过随机数字表法将2020年5月至2022年5月菏泽市中医医院收治的60例妊娠剧吐孕妇分为对照组(30例)和观察组(30例),对照组给予维生素B6治疗,观察组给予维生素B6+间苯三酚治疗,记录两组的治疗相关时间、妊娠恶心呕吐专用量表(PUQE)评分、妊娠恶心呕吐生活质量量表(NVPQOL)和不良反应发生率。结果观察组呕吐改善、尿酮体转阴和住院时间与对照组相比较短(P<0.05)。与对照组比较,观察组治疗后PUQE、NVPQOL评分较低(P<0.05)。两组不良反应发生率比较无统计学差异(P>0.05)。结论间苯三酚与维生素B6联合应用具有较高的安全性,用药后可有效加强孕妇胃肠运动,改善进食欲望,并减轻呕吐症状,有利于促使孕妇康复,进而提升其生活质量。

甲氧氯普胺联合异丙嗪对妊娠剧吐患者呕吐症状及生活质量的影响

目的分析甲氧氯普胺联合异丙嗪在妊娠剧吐患者中的治疗效果。方法方便选取2020年5月-2022年4月六盘水市人民医院收治的妊娠剧吐患者86例为研究对象,按随机数表法分为两组,各43例。对照组予以甲氧氯普胺,观察组加用异丙嗪,连续治疗1周。对比两组临床疗效、症状改善情况、呕吐症状严重程度、生活质量、不良反应。结果观察组治疗总有效率为93.02%,高于对照组的76.74%,差异有统计学意义(χ^(2)=4.441,P<0.05),观察组的呕吐消失时间、尿酮转阴时间短于对照组,差异有统计学意义(P均<0.05);治疗前,两组孕期恶心呕吐量化表(Pregnancy-unique Quantification of Emesis and Nausea,PUQE)评分与妊娠恶心呕吐生活质量量表(Nausea and Vomiting of Pregnancy Quality of Life Questionnaire,NVPQOL)评分相比,差异无统计学意义(P均>0.05)。治疗后,观察组PUQE评分、NVPQOL评分低于对照组,差异有统计学意义(P均<0.05);两组不良反应比较,差异无统计学意义(P>0.05)。结论甲氧氯普胺+异丙嗪治疗妊娠剧吐患者效果显著,可减轻其呕吐症状,促进尿酮转阴,提升生活质量,且无严重不良反应。

2-氨基-4-乙酰基嘧啶的合成研究

2-氨基-4-乙酰基嘧啶是乙酰基嘧啶类具有较好生物活性的一种杂环化合物,是制备含嘧啶环的磺胺类药物和磺酰脲类除草剂的重要中间体。研究了2-氨基-4-乙酰基嘧啶的合成途径和合成方法,阐述了用2,3-丁二酮合成2-氨基-4-乙酰基嘧啶的操作步骤和过程,对过程中遇到的问题及解决方法进行了说明,并通过新路径下的操作过程优化确定了最优反应参数和最终路线,为2,3-丁二酮合成2-氨基-4-乙酰基嘧啶探索出了一条安全、高效、高产的合成途径。

Highly efficient synthesis of β-amino esters via Mannich-type reaction under solvent-free conditions using ZnCl_2 catalyst

β-Amino esters were synthesized via ZnCl2-catalyzed Mannich-type reaction of imines and malonate esters under solvent-free conditions in 6 min. The β-amino ester was converted into the corresponding aspartic acid derivatives.

A New Reformatsky Type Reaction Via Cadmium Salt In Aqueous Media

In the presence of cadmium (II) chloride-metallic samarium, alpha-bromoacetophenone reacts with aldehydes in THF -H2O under mild conditions to give beta-hydroxy ketones in good yields.

A New Investigation of Mannich Reaction

During the synthesis of the derivatives of styryl ketonic Mannich bases, a side -product IM,other than the normal Mannich base MA, is obtained. Mannich reaction is further studied and the formation mechanism of product IM is postulated and discussed on the basis of deuterium labelling.