征服“不可驯服元素”的启示

在化学元素周期表第七族的主族中,共有五个元素,即氟、氯、溴、碘、砹。除砹是人工合成元素外,其他均以化合物的形式存在于自然界中。在卤族元素中,氯是第一个被发现的,是瑞典化学家席勒(C.W.Scheele)于1774年获得的。碘,是法国一位药剂师别尔恩加尔特·库尔图阿(B.Courtois)于1811年从海藻中发现的。溴,是法国另一位药剂师巴拉德(A.J.     

钚及其元素符号Pu的来源

94号元素杯是美国核化学家,1951诺贝尔化学奖得主之一西博格(G. T. Seaborg)等人于1940年发现的。     

镉元素的发现及其概念的发展

通过对镉元素概念发展历程的考证分析可知,19世纪初,随着科学思想和化学分析方法的发展,德国化学家斯特罗迈耶首次通过药物分析制取并命名镉单质。至1826年,瑞典化学家贝采利乌斯首次测定镉原子量,赋予镉元素新的含义。镉原子量测定以及元素周期表形成,使镉元素的概念和镉原子结合起来。1924年,英国化学家阿斯顿通过质谱仪发现了镉同位素,从而形成了现代的镉元素概念。总之,随着科学思想和方法的不断发展,镉元素概念的内涵也在不断发展变化。     

钛元素的发现及其概念发展

1791年,英国矿物学家格雷戈尔发现钛矿石并意识到一种新元素的存在。至1795年,普鲁士化学家克拉普罗特进一步预言了该元素,并将之正式命名为钛(Titanium)。1910,美国化学家亨特制取了纯净的钛单质,钛元素的概念正式形成。20世纪20年代以后,钛同位素的发现使人们对钛元素概念有了新认识,并逐渐形成现代钛元素概念。钛元素概念的发展使人们在科学认知上发生了转变,促进了化学元素观的演进。     

烷烃的自由基溴化

作者用N-溴代二乙胺和典型溴化剂N-溴代丁二酰亚胺分别对正戊烷、正己烧、正庚烷进行了光溴化,并与元素溴对烷烃直接光溴化进行了比较。 工作中找到了分离烷基溴化物的气相色谱条件,从而确定了元素溴对三种烷烃光溴化产物异构体的分布,并发现上述两种溴化剂光溴化产物的异构体分布与元素溴直接溴化结果基本相同。     

海洋溴吡咯生物碱的研究进展

大量的溴吡咯生物碱从海绵中得到分离, 并表现出良好的生理活性. 这类化合物因其结构的新颖性、多样性、以及良好的生理活性而成为合成化学家关注的焦点. 综述了近年来海洋溴吡咯生物碱的分离和合成进展.     

第一个人工合成元素锝：化学家与物理学家合作的结晶

1871年，门捷列夫依据元素周期律和元素周期表预见了“类锰”（即锝元素）的存在；至20世纪，随着科学家对原子核变化的研究进展、回旋加速器的发明以及人工放射性元素的发现，化学家和物理学家一起用回旋加速器加速的氚核轰击钼靶得到了锝元素。锝成为了第一个人工合成的元素，是化学家与物理学家合作的结晶。它的发现不仅显示了先进的科学方法和科学仪器的重要作用，也证明了学科间合作的重要性。     

门捷列夫周期律

我们国家的科学界,在1954年里有两个历史性的日子,那就是伟大的俄罗斯化学家德米特里·伊凡诺维奇·门捷列夫诞辰(1834年2月8日)120周年,和他发现化学元素的周期律85周年。 1869年初,彼得堡大学教授Д.И.门捷列夫将他根据元素的原子量和化学的相似性质制定的元素系统表示式的文件(图1),分送给许多化学家。在1869年3月6日举行的俄罗斯化学学会第十八次会议上,Н.А.门舒特金代表门捷列夫,作了关於发现周期律和与其相联系的化学元素系统的第一个报导。     

氩元素概念的形成和发展与化学思想的演进

19世纪末英国化学家瑞利和拉姆塞发现了氩元素，引发了“惰性气体”的发现，开辟了周期表中的零族元素；20世纪20年代氩元素同位素的发现使人们对氩元素的概念有了新认识；21世纪初，氩化合物的发现使人们对氩的“惰性”有了全新的认识，改称氩为稀有气体元素。总之，氩元素概念的形成和发展对于元素周期律的完善和发展，以及人们对原子结构和化学键理论的认识都起到了极为重要的桥梁作用。     

钨元素的发现及其概念的发展

1781年,瑞典化学家舍勒在白钨矿中发现了钨酸,预测其中一定含有一种新金属元素,并将其命名为钨(Tungsten)。1783年,西班牙化学家德鲁亚尔兄弟从黑钨矿中成功提取出了舍勒所说的新金属单质,将其命名为钨(Wolfram)。1803年,英国化学家道尔顿原子论的提出,赋予钨元素新的含义:具有一定质量的钨原子。1930年以后,钨同位素的发现使人们对钨元素有了新认识,并逐渐形成了现代钨元素的概念。关于钨元素的认识经历了从假说到客观存在、从定性到定量、从宏观到微观的发展历程。钨元素概念的演变体现了科学思想和科学方法的进步。     

On the bromination of 1,7- and 1,8-Naphthyridine in nitrobenzene

By application of the Kress procedure for bromination it has been found that from the hydro-bromide of 1,7-naphthyridine with 1.1 equivalents of bromine in nitrobenzene a mixture of 3-and 5-bromo- and 3,5-dibromo-1,7-naphthyridine is obtained in reasonable yield. With an excess of bromine 3,5-dibromo-1,7-naphthyridine is nearly exclusively formed. Similar brominations of the hydrobromide of 1,8-naphthyridine with 1.1 equivalents of bromine gave 3-bromo- and 3,6-dibromo-1,8-naphthyridine. By using an excess of bromine a high-yield conversion into 3,6-dibromo-1,8-naphthyridine is observed. Bromination of the hydrochloride salt of 1,7- and 1,8-naphthyridine affords the same bromo derivatives.     

纤维素基磁性聚偕胺肟树脂的研究——循环吸溴中吸附与还原能力的变化

研究了酸式纤维素基磁性聚偕胺肟树脂（ＡＭＡＯ）在循环吸溴过程中吸附容量和还原能力的变化，发现原树脂的吸溴初速和溴的还原率比再生树脂高一倍以上，但第一次和第二次再生树脂的吸附速度和还原效率几乎相同，暗示着树脂吸溴后基本结构已发生了彻底的变化．树脂在循环使用时吸溴容量变化不大而溴的还原量却显著降低，表明ＡＭＡＯ作为吸溴剂有较高的实用价值．     

Bromination of Mono- and Bisammonium Salts with a 4-Penten-2-ynyl Side Group

Reaction of bromine with 1,4-bisammonium salts containing, along with a 2-chlorobutenylene common fragment, 4-penten-2-ynyl side groups, as well as of monoammonim salts containing the same side group and a 4-bromo-3-chlorobutenyl group, involve addition of two bromine molecules at each of the side groups, while the double bond of the chlorobutenyl group remains intact.     

A New Route to Thio- and Selenosulfonates from Disulfides and Diselenides. Application to the Synthesis of New Thio- and Selenoesters of Triflic Acid

Alkyl and aryl trifluoromethanethiosulfonates(1) (or selenosulfonates) were prepared in one step either from alkyl and aryl sulfenyl (or selenenyl) chlorides and sodium trifluoromethanesulfinate (3) or, more generally, from disulfides (or diselenides), 3, and bromine. The second method involved trifluoromethanesulfonyl bromide as key intermediate. Benzenethiosulfonates were obtained in a similar way from disulfides, benzenesulfinate, and bromine but benzeneselenosulfonates could not be obtained by the same method from diselenides.     

Preparation of a novel bromine complex and its application in organic synthesis

Although molecular bromine (Br₂) is a useful brominating reagent, it is not easy to handle. Herein, we describe the preparation of a novel air-stable bromine complex prepared from 1,3-dimethyl-2-imidazolidinone (DMI) and Br₂, which was identified to be (DMI)₂HBr₃ by spectral and X-ray techniques. This complex was then used to brominate olefins, carbonyl compounds, and aromatics, as well as in the Hofmann rearrangement. Yields of reaction products using this complex were almost the same or superior to those using other bromine alternatives.     

Structural peculiarities of some diphenyl ether derivatives

Conclusions On bromination of diphenyl ether the first bromine atom enters into the hydrocarbon ring, and the second bromine atom enters into the ethereal ring. The same principle was found for the chloromethylation of diphenyl ether.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 142–144, January, 1969.     

A method for functional analysis of organosilicon compounds containing silacyclobutane groups

A method of determining quantitatively silacyclobutane rings in organosilicon compounds is worked out. It is based on addition of bromine or iodine to a Si-C bond in the ring, followed by determination of those elements in the resultant Si-Br or Si-I group. The error in determining bromine or iodine numbers by the method is 0.5–2.0%; the error in determining percentage bromine (iodine) is 0.5–2.0%. A determination takes 3–4 hr. The silacyclobutane group does not react with thiocyanogen, so that it is possible to determine separately multiple bonds and silacyclobutane groups present in one and the same molecule.     

The mass spectral behavior of β-bromoethyl benzoate and some of its ring substituted derivatives: Evidence for oxygen participation in the formation of [M ? Br]+

The expulsion of a bromine atom from the molecular ion of β-bromoethyl benzoate displays a kinetic behavior which resembles that of a rearrangement reaction. The two oxygen atoms in the resulting [M ? Br]⁺ ion become equivalent before or during the secondary decomposition of this ion, as shown by oxygen labeling. In addition, the primary ions generated from benzophenone ethylene ketal and acetophenone ethylene ketal by phenyl and methyl expulsion, respectively, undergo subsequent fragmentation in the same way as the [M ? Br]⁺ from β-bromoethyl benzoate. These results strongly indicate that the carbonyl-oxygen atom participates in the expulsion of bromine. The effect of ring substituents on the competing loss of bromine and McLafferty rearrangement is also discussed.     

Research on a number of substituted arylamides of dithiocarboxylic acids

Dithiomalonic acid diarylamldes are cyclized to 3,5-diarylamino-1,2-dithiolium halides by oxidation with an equivalent amount of bromine (iodine) in chloroform solution; the same amides are cyclized to 4-bromo-3,5-diarylamino-1,2-dithiolium bromides with excess bromine and to 3-arylamino-5-arylimino-1,2-dithiols in alkaline media with potassium ferricyanide. The behavior of the synthesized substituted 1,2-dithiols with respect to various reagents was studied.     

Occurrence of bromine in plants and soil

The usefulness of X-ray fluorescence analysis for the determination of bromine in soil and plants is demonstrated by comparing the results with those obtained by activation analysis. An abnormal accumulation of bromine in some soils, plants and cigarettes has been found. Volcanic ash soil accumulates bromine in its humic acid. The large ratio of chlorine to bromine in river water may be explained by the accumulation of bromine in humus of soil. The possibility of bromine contamination of food and cigarettes, due to the application of agricultural chemicals, is pointed out.