2,3,6-三氯吡啶选择性脱氯制2,3-二氯吡啶的研究

采用过量浸渍法制备了Pd/C催化剂,用2,3,6-三氯吡啶选择性脱氯制备2,3-二氯吡啶的反应,评价了催化剂的性能,考察了钯负载量、反应温度和缚酸剂对催化剂活性的影响。结果表明,在钯负载量为0.5%(wt)、反应温度为140℃的条件下,催化剂上2,3,6-三氯吡啶的转化率达100%,产物2,3-二氯吡啶的选择性大于71%,在溶剂甲醇中添加三乙胺后能够有效的提高目标产物的选择性,较优条件下2,3-二氯吡啶的选择性可以达到80%。     

高效液相色谱法测定3-氨基哌啶二盐酸盐中氨基吡啶类基因毒性杂质的含量

在降血糖药物苯甲酸阿格列汀的合成过程中,有可能因原料的因素而引入氨基吡啶类基因毒性杂质而对上述药物的用药安全性造成影响。为此试验提出了用高效液相色谱法测定3-氨基哌啶二盐酸盐中3种氨基吡啶化合物(4-氨基吡啶、3-氨基吡啶和2-氨基吡啶)的方法。称取试样0.3g,用磷酸盐缓冲溶液(pH 7.0)-甲醇(90+10)混合溶液超声溶解并定容至10.0mL。选择Shim-pack Scepter C_(18)色谱柱作为分离柱,用pH 7.0的磷酸盐缓冲溶液和甲醇(90+10)的混合溶液等度洗脱,流量为0.5mL·min~(-1),柱温为35℃,检测波长为280nm,进样量10μL。在选定的条件下,上述3种化合物可达到很好的分离,4-氨基吡啶、3-氨基吡啶和2-氨基吡啶间的分离度分别为30.3,8.4,其检出限(3S/N)分别为0.028 9,0.071 1,0.070 2mg·L~(-1)。在3个浓度水平上对3种化合物进行回收试验,测得回收率依次为101%,98.4%,97.2%。重复性和重现性试验所测得3种化合物测定值的相对标准偏差(n=6)分别依次为1.5%,0.90%,0.70%和6.2%,3.0%,2.2%。样品加标溶液和对照品溶液在室温下放置24h内稳定性良好。     

2-氨基-2-(2-甲氧基-5-吡啶)乙醇的合成研究

2-氨基-2-(2-甲氧基-5-吡啶)乙醇是一种重要的药物中间体。本论文提供一种以2-甲氧基吡啶-5-甲酸为原料,经过7步反应制备2-氨基-2-(2-甲氧基-5-吡啶)乙醇的方法,每步反应产率均高于78%,总收率约为23%,最终产品纯度大于98.5%。     

基于吡啶-水体系的2′-羟基查耳酮环化反应研究

以2′-羟基查耳酮为原料,吡啶-水溶液为催化剂,分别在加热和光照条件下合成黄烷酮,考察了吡啶-水体积比、加热温度、光照强度、反应时间等因素的影响。结果表明,当吡啶-水体积比为4∶6,加热温度为90℃,反应时间为1 h时,黄烷酮产率达89.0%;在吡啶-水体积比为4∶6下,采用500W氙灯辐射7.5 h,黄烷酮产率达93.7%。     

2-氨基-6-甲氧基-3-硝基吡啶的合成

以2-氯-5-硝基吡啶为原料,经甲氧基化反应得2-甲氧基-5-硝基吡啶(2),2再与液氨/高锰酸钾进行氨化反应制得2-氨基-6-甲氧基-3-硝基吡啶,总收率77%。     

Co-MCM-41催化H2O2氧化4-甲基吡啶生成4-吡啶甲酸的反应条件及机理

研究了乙酸溶剂中无引发剂条件下,Co掺杂MCM-41催化过氧化氢（30%）氧化4-甲基吡啶的反应,催化剂表现出高底物转化率和产物吡啶甲酸选择性以及良好的再生性。 探讨了不同溶剂、反应时间、反应温度、催化剂用量等对H2O2氧化4-甲基吡啶反应的影响,确定较优反应条件为m（4-甲基吡啶)∶m（催化剂)=10∶1,V（4-甲基吡啶)∶V（冰醋酸)=1∶10,温度363 K,时间6 h。 该条件下4-甲基吡啶的转化率为96.5%,4-吡啶甲酸的选择性为91.4%。 探讨了可能的反应机理。     

离子色谱-紫外检测法分离测定吡啶离子液体阳离子

建立了用离子色谱-紫外检测法分离测定3种吡啶离子液体阳离子(N-乙基吡啶、N-丁基吡啶和N-丁基四甲基吡啶)的方法。采用磺酸型阳离子交换柱,以乙二胺-柠檬酸-乙腈为流动相,考察了流动相和色谱柱温度对离子保留的影响,探讨了保留规律。实验发现,吡啶阳离子的保留过程是放热过程。优化的色谱条件为：流动相是0.2 mmol//L乙二胺-0.3 mmol//L柠檬酸-0.5%(v/v)乙腈(pH 4.2),流速1.0 mL/min,柱温30℃。在此条件下可以基线分离3种吡啶阳离子。所测阳离子的检出限(S/N=3)分别为0.01、0.01、0.02 mg/L,峰面积的相对标准偏差(n=5)小于0.8%。将此方法应用于分析实验室合成的吡啶离子液体样品,加标回收率在96.3%～103.7%之间。本方法准确、可靠、快速,具有较好的实用性。     

负载型纳米贵金属催化剂催化吡啶及其衍生物的加氢反应

 制备了负载型高分散的纳米贵金属催化剂和含Ru的双金属催化剂,并考察了催化剂对吡啶及其衍生物加氢反应的催化性能. 结果表明, 5%Ru/C催化剂对吡啶加氢反应的催化活性高于5%Pd/C, 5%Pt/C和5%Ir/C. 在100 ℃, 3.0 MPa, 1 h和Ru/吡啶摩尔比=2.5/1000 的条件下, 5%Ru/C催化吡啶加氢的转化率大于99.9%, 生成哌啶的选择性为100%. 催化剂重复使用5次后,活性和选择性无明显下降. 在Ru催化剂中加入少量的Pd和Ir后催化剂活性没有明显的变化. 采用X射线衍射、高分辨透射电镜和X射线光电子能谱对还原后的5%Ru/C催化剂进行表征,结果表明Ru以高分散金属态存在,其平均粒径小于5 nm. 不同底物的加氢反应活性为: 吡啶≈2-甲基吡啶>2,6-二甲基吡啶>3-甲基吡啶>4-甲基吡啶>3,5-二甲基吡啶>2-甲氧基吡啶.     

改进的2-巯基-5-甲氧基咪唑并[4,5-b]吡啶合成法

以2,6-二氯吡啶为起始原料,经甲氧基化、硝化、氨基化、还原及成环5步反应得到2-巯基-5-甲氧基咪唑并[4,5-b]吡啶,总收率45.7%。重点比较了2-氯-6-甲氧基吡啶和2,6-二氯吡啶硝化反应条件及收率的差异,讨论了水合肼、NaOH的用量对目标产物收率的影响。用1HNMR、MS和IR测试技术对目标产物结构进行了表征。     

重铬酸钾氧化法合成2-吡啶甲酸的研究

研究了以2-甲基吡啶为原料,以重铬酸钾为氧化剂,利用化学氧化法合成2-吡啶甲酸的反应条件.考察了反应温度、反应物2-甲基吡啶的浓度和与重铬酸钾的浓度比例、硫酸浓度和反应时间对产率、转化率及选择性的影响,其产物用红外、元素分析和熔点分析表征.实验表明,最佳反应条件:反应温度105℃,2-甲基吡啶摩尔浓度为0.075mol/L,重铬酸钾与2-甲基吡啶浓度比为2∶1,硫酸浓度为9 mol/L,反应时间为2 h,其转化率可达97.6%,2-吡啶甲酸的色谱产率可达87.7%,选择性为89.8%.     

2-氯吡啶气相光氯化反应机理的量子化学研究

用量子化学DFT方法在B3LYP/3-21G^*水平下研究了2-氯吡啶气相光氯化取代反应生成2,3-二氯吡啶、2,4-二氯吡啶、2,5-二氯吡啶和2,6-二氯吡啶不同产物的过渡态,并计算了活化能.结果表明,生成2,6-二氯吡啶过渡态的能量最低,所需的活化能也最低,反应优先生成2,6-二氯吡啶.生成2,6-二氯吡啶的IRC结果显示反应过程中C-H键的断裂和C-C l键的生成协同但不同步.过渡态的构型接近于产物,是一个晚期过渡态.C l原子在反应进程中是给电子的,因此,氯自由基与2-氯吡啶反应是亲核取代的SN2机理.     

Radiolysis and photolysis of crystalline 2,4,6-triazido-3,5-dichloropyridine: Generation of Quintet dinitrenes

Low-temperature radiolysis and photolysis of crystalline 2,4,6-triazido-3,5-dichloropyridine (TAP) were studied by means of the ESR technique. It was found that the long-term irradiation of TAP at 77 K leads to the appearance of characteristic signals of quintet 2,6-dinitreno-4-azido-3,5-dichloropyridine and 2,4-dinitreno-6-azido-3,5-dichloropyridine; their radiation-chemical yield was 0.035 and 0.012 molecule/100 eV, respectively. The photolysis of crystalline 2,4,6-triazido-3,5-dichloropyridine proceeded less effectively, producing only quintet 2,6 dinitrene with a quantum yield of ～4.5 × 10^?4. The study showed that the generation of high-spin nitrenes via radiolysis of crystalline azides is much superior to the photochemical technique in efficiency and may be of practical importance for the preparation of magnetically active organic materials.     

The properties of quintet dinitrenes in 2,4,6-triazido-3,5-dichloropyridine crystals

The gamma radiolysis of crystalline 2,4,6-triazido-3,5-dichloropyridine (TACP) was studied by the EPR method. The molecular and crystal structure of TACP was determined by X-ray structure analysis. The prolonged radiolysis of TACP at 77 K caused the appearance of characteristic EPR signals of quintet 2,6-dinitreno-4-azido-3,5-dichloropyridine (2,6-DN) and 2,4-dinitreno-6-azido-3,5-dichloropyridine (2,4-DN). The predominant decomposition of the α-azide groups of TACP was explained by the special features of its molecular and crystal structure. The saturation of the EPR signals of quintet 2,6-DN and 2,4-DN and one-electron radicals with S = 1/2 as the microwave field power increased was studied. The quintet dinitrenes were found to be thermally unstable; they remained in TACP crystals up to 245–250 K.     

抗溃疡新药——泰妥拉唑的合成工艺改进

对新型质子泵抑制剂泰妥拉唑(7)的合成工艺进行了改进。以2,6-二氯吡啶为起始原料,经7步反应合成了7,总收率从20.9%提高到49.8%。7的其结构经1HNMR,MS和元素分析表征。     

Electrochemical coupling of mono and dihalopyridines catalyzed by nickel complex in undivided cell

One step nickel-catalyzed electroreductive homocoupling among 2-bromopicolines and 2-bromopyridine has been investigated by our group in an undivided cell and using zinc or iron as sacrificial anode. In this work, it was developed mono and dihalopyridines coupling to obtain possible products from heterocoupling. A series of reactions were carried out in order to develop a synthetic method for the preparation of unsymmetrical 2,2′-bipyridines and 2,2′:6′,2″-terpyridines. Statistical yields (50%) were observed for 2-bromopyridines/2-bromo-6-methylpyridine heterocoupling. In a preliminary study devoted to terpyridines preparation, good results were obtained for 2,6-dihalopyridines homocoupling, affording 2,6-dichloro-2,2′-bipyridine (46%) and 2,6-dibromo-2,2′-bipyridine (56%), at controlled reaction time. At major reaction time, it was observed that the direct electroreduction of the 2,6′-dihalo-2,2′-bipyridines intermediates and 2,6″-dihalo-2,2′:6′,2″-terpyridines products on the cathode surface. A reasonable isolated product yield of 6,6″-dimethyl-2,2′:6′,2″-terpyridine (10%) was only observed in the reaction between 2,6-dichloropyridine and 2-bromo-6-methylpyridine (1:2).     

5-氨基-6-硝基-[1,2,5]噁二唑并[3,4-b]吡啶-1-氧化物的新法合成

以2,6-二氯吡啶为起始原料,经肼基化、还原、硝化、Nietzki-Dietschy环合4步反应得到5-氨基-6-硝基-[1,2,5]噁二唑并[3,4-b]吡啶-1-氧化物.结合反应机理讨论了还原、硝化、Nietzki-Dietschy环合反应的影响因素,获得了合成-.氨基-6-硝基-[1,2,5]噁二唑并[3,4-b]吡啶-1-氧化物的最佳工艺条件,目标产物的总收率为59.2%.用1H NMR、MS和IR谱对5-氨基-6-硝基-[1,2,5]噁二唑并[3,4-b]吡啶-1-氧化物的结构进行了表征.     

Single-flask preparation of polyazatriaryl ligands by sequential borylation/Suzuki-Miyaura coupling

We report a convenient single-flask methodology for the preparation of polyazatriaryl products with relevance to luminescence, catalysis, and pharmacology. The diborylation of 1,3-dibromobenzenes and double Suzuki-Miyaura coupling produces 1,3-diheteroarylbenzenes. Similarly, borylation of heteroaryl halides and double coupling to 2,6-dichloropyridine produces 2,6-diheteroarylpyridines. This methodology appears general in producing challenging polyheteroaryl targets as long as the boronic esters have no ortho heteroatoms and coupling avoids adjacent oxygens.     

2,4,6-tris(methylsulfonyl)-3,5-dichloropyridine

The reactions of 2,6-bis(methylthio)-3,4,5-trichloropyridine and its N-oxide with sodium hydrosulfide were studied. A method for the synthesis of 2,4,6-tris(methylsulfonyl)-3,5-dichloropyridine was developed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3. pp. 369–371, March, 1976.     

Photoassisted oxygenation of alkane catalyzed by ruthenium complexes using 2,6-dichloropyridine N-oxide under visible light irradiation

The chloro(Me(2)SO)ruthenium(II) complexes with tris(2-pyridylmethyl)amine or its derivative catalyses the selective, stereospecific, and photoregulative alkane oxidation in the presence of 2,6-dichloropyridine N-oxide under visible light irradiation.