971 resultados para Hydrogen Bond


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Letter which was enclosed with the application, bond mortgage and abstract of the Jones and Mater accounts to Samuel Woodruff from Jarvis, Conklin and Co., May 4, 1882.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Printed blank of Statement of Security Form naming the bond as Jones County Texas Bonds for the purpose of building a courthouse. It is made out to S.D. Woodruff and dated June 12, 1885. An envelope addressed to Mr. S.D. Woodruff is also included. The postmarks are Kansas, 1885 and St. Catharines, June 13, 1885.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The exact mechanistic understanding of various organocatalytic systems in asymmetric reactions such as Henry and aza-Henry transformations is important for developing and designing new synthetic organocatalysts. The focus of this dissertation will be on the use of density functional theory (DFT) for studying the asymmetric aza-Henry reaction. The first part of the thesis is a detailed mechanistic investigation of a poorly understood chiral bis(amidine) (BAM) Brønsted acid catalyzed aza-Henry reaction between nitromethane and N-Boc phenylaldimine. The catalyst, in addition to acting as a Brønsted base, serves to simultaneously activate both the electrophile and the nucleophile through dual H-bonding during C-C bond formation and is thus essential for both reaction rate and selectivity. Analysis of the H-bonding interactions revealed that there was a strong preference for the formation of a homonuclear positive charge-assisted H-bond, which in turn governed the relative orientation of substrate binding. Attracted by this well-defined mechanistic investigation, the other important aspect of my PhD research addressed a detailed theoretical analysis accounting for the observed selectivity in diastereoselective versions of this reaction. A detailed inspection of the stereodetermining C-C bond forming transition states for monoalkylated nitronate addition to a range of electronically different aldimines, revealed that the origins of stereoselectivity were controlled by a delicate balance of different factors such as steric, orbital interactions, and the extent of distortion in the catalyst and substrates. The structural analysis of different substituted transition states established an interesting dependency on matching the shape and size of the catalyst (host molecule) and substrates (guest molecules) upon binding, both being key factors governing selectivity, in essence, offering an analogy to positive cooperative binding effect of catalytic enzymes and substrates in Nature. In addition, both intra-molecular (intra-host) and inter-molecular (host-guest, guest-guest) stabilizing interactions play a key role to the high π-facial selectivity. The application of dispersion-corrected functionals (i.e., ωB97X-D and B3LYP-D3) was essential for accurately modeling these stabilizing interactions, indicating the importance of dispersion effects in enantioselectivity. As a brief prelude to more extensive future studies, the influence of a triflate counterion on both reactivity and selectivity in this reaction was also addressed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Bond (1 page, printed) between Isaac Sterling of the Township of Salt fleet to William Dickson of Niagara and Thomas Clark of Queenston (regarding the Last Will and Testament of Robert Hamilton) for payment of 153 pounds, 12 shillings and 3 pence to be made to Dickson and Clark, May 21, 1819.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Bond (1 page, printed) between Archibald Johnston of the Township of Bertie to William Dickson of Niagara and Thomas Clark of Queenston (regarding the Last Will and Testament of Robert Hamilton) for payment of 75 pounds to be made to Dickson and Clark, June 7, 1821.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Bond (1 page, printed) between Daniel Cornell of the County of Oxford to William Dickson of Niagara and Thomas Clark of Stamford (regarding the Last Will and Testament of Robert Hamilton) for payment of 103 pounds, 11 shillings and 1 penny to be made to Dickson and Clark, July 12, 1822.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Bond (1 page, printed) between John Hammell of the Township of Dumphries, Halton County to William Dickson of Niagara for 117 pounds, 10 shillings and 10 pence, Sept. 21, 1824.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Bond (1 page, printed) between Alexander Fraser of the Township of Dumphries to the Honourable William Dickson of Galt for 304 pounds, June 21, 1830.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Bond (1 page, printed) between Abram Quackenboss of Dumphries to the Honourable William Dickson of Galt for 400 pounds, Oct. 27, 1836.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Marriage Bond between Harrison Narrel of Gainsborough and Anna Simmermon of Clinton signed by Andrew Snyder of Gainsborough and William Jacobs of Grimsby, Sept. 1, 1834

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Marriage Bond between Henry Chambers of Ancaster and Sarah Smith of Ancaster signed by Charles Anderson of Grimsby and Robert F. Nelles of Grimsby, Dec. 27, 1836.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Marriage Bond between John Smith of Glanford in the Gore district and Jane Atkins of Ancaster signed by Edmund Smith of Ancaster and Jeremiah Smith of Glanford, Jan. 17, 1837.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Marriage Bond between Joseph Bridgeman of Grimsby and Calinda Ann Lounsberry of Grimsby signed by Palmer Buckbee of Grimsby and Robert F. Nelles of Grimsby, July [?] 6, 1837.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Marriage Bond between Henry Stratton of Grimsby and Elizabeth Muir of Grimsby signed by William Crooks of Grimsby and Robert F. Nelles of Grimsby, June 7, 1838.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Marriage Bond between Thomas A. Allen of Grimsby and Sarah Bridgeman of Grimsby signed by Adam Duff of Grimsby and Palmer Bugbee [Buckbee] of Grimsby, Sept. 28, 1838.