Substituent Effects in Benz[<i>a</i>]anthracene Carbocations: A Stable Ion, Electrophilic Substitution (Nitration, Bromination), and DFT Study
作者:Kenneth K. Laali、Maria A. Arrica、Takao Okazaki、Ronald G. Harvey
DOI:10.1021/jo070936r
日期:2007.8.31
computed relative energies by DFT. Charge delocalization paths in the resulting carbocations were deduced based on the magnitude of Δδ13C values. For the thermodynamically more stable C-12 protonated carbocations, the charge delocalization path is analogous to those derived based on computed NPA charges for the benzylic carbocations formed by 1,2-epoxide (bay-region) and 5,6-epoxide (K-region) ring opening
在FSO 3 H / SO 2 ClF中通过低温质子化作用,由异构的单烷基化和二烷基化的苯并[ a ]蒽(BAs)生成了一系列新型的碳正离子化反应。C-7具有单烷基衍生物(5-甲基,6-甲基,7-甲基和7-乙基)以及D环甲基化类似物(9-甲基,10-甲基和11-甲基),或在所有情况下均观察到C-12质子化的碳正离子(作为唯一或主要的碳正离子)。12-甲基衍生物的质子化(9)得到C-7质子化的碳正离子(9H +)作为动能种类和本位-protonated碳阳离子(9AH +)作为热力学阳离子。与12-乙基衍生物(10),在箱式区域空间张力的浮雕大大有利于本位-protonation(10AH +)。具有3,9-二甲基(14),C-7质子化(14H +)(C-12质子化<10%)受到强烈青睐,在1,12-二甲基(15)的情况下,观察到的唯一物质是C-7质子化的碳正离子化(15H +)。对于7-甲
Partnering for e-government: Challenges for public administrators
作者:John Langford、Yuonne Harrison
DOI:10.1111/j.1754-7121.2001.tb00898.x
日期:2001.12
Abstract: Governments around the world are spending huge sums of money implementing electronic government. Public‐private partnerships with information and communication technology firms have emerged as the vehicle of choice for implementing e‐government strategies. Concerns are raised about the capacity of governments to manage these complex, multi‐year, often multi‐partner relationships that involve considerable sharing of authority, responsibility, financial resources, information and risks. The management challenges manifest themselves in the core partnering tasks: establishing a management framework for partnering; finding the right partners and making the right partnering arrangement; the management of relationships with partners in a network setting; and the measurement of the performance of e‐government partnerships. The article reviews progress being made by governments in building capacity to deal with these core partnering tasks. It concludes that many new initiatives at the central agency and departmental/ministry level seem designed to centralize control of e‐government projects and wrap them in a complex web of bureaucratic structures and processes that are, for the most part, antithetical or, at best, indifferent to the creation of strong partnerships and the business valuethat e‐government public‐private partnerships promise.
Adrenocorticolytic derivatives of benz[.alpha.]anthracene