The structure of a typical double-ring planetary nebula NGC 2392

1981 ◽  
Vol 79 (1) ◽  
pp. 229-237 ◽  
Author(s):  
R. Louise
Keyword(s):  
Planetary Nebula ◽  
Double Ring

Spectrum and chemical analysis of the double-ring planetary nebula IC 1297

1986 ◽  
Vol 311 ◽  
pp. 930 ◽  
Author(s):  
Lawrence H. Aller ◽  
Charles D. Keyes ◽  
Walter A. Feibelman
Keyword(s):  
Chemical Analysis ◽  
Planetary Nebula ◽  
Double Ring

A kinematic determination of the structure of the double ring planetary nebula NGC 2392, the Eskimo

1990 ◽  
Vol 362 ◽  
pp. 226 ◽  
Author(s):  
C. R. O'dell ◽  
Larry D. Weiner ◽  
You-Hua Chu
Keyword(s):  
Planetary Nebula ◽  
Double Ring

Double Ring-Closing Approach for the Synthesis of 2,3,6,7-Substituted Anthracene Derivatives

2020 ◽  
Author(s):  
Birgit Meindl ◽  
Katharina Pfennigbauer ◽  
Berthold Stöger ◽  
Martin Heeney ◽  
Florian Glöcklhofer
Keyword(s):  
Wittig Reaction ◽  
Condensation Reaction ◽  
Synthetic Methods ◽  
Anthracene Derivative ◽  
Double Ring ◽  
Mild Conditions ◽  
Wide Range ◽  
Anthracene Derivatives

Anthracene derivatives have been used for a wide range of applications and many different synthetic methods for their preparation have been developed. However, despite continued synthetic efforts, introducing substituents in some positions has remained difficult. Here we present a method for the synthesis of 2,3,6,7-substituted anthracene derivatives, one of the most challenging anthracene substitution patterns to obtain. The method is exemplified by the preparation of 2,3,6,7-anthracenetetracarbonitrile and employs a newly developed, stable protected 1,2,4,5-benzenetetracarbaldehyde as the precursor. The precursor can be obtained in two scalable synthetic steps from 2,5-dibromoterephthalaldehyde and is converted into the anthracene derivative by a double intermolecular Wittig reaction under very mild conditions followed by a deprotection and intramolecular double ring-closing condensation reaction. Further modification of the precursor is expected to enable the introduction of additional substituents in other positions and may even enable the synthesis of fully substituted anthracene derivatives by the presented approach.<br>

Angular Expansion Measurement of the Young and Compact Planetary Nebula V[CLC]y[/CLC] 2-2

1998 ◽  
Vol 115 (6) ◽  
pp. 2466-2474 ◽  
Author(s):  
Haryadi Christianto ◽  
E. R. Seaquist
Keyword(s):  
Planetary Nebula ◽  
Angular Expansion

High‐Resolution X‐Ray Image of the Hydrogen‐deficient Planetary Nebula Abell 30

1997 ◽  
Vol 482 (2) ◽  
pp. 891-896 ◽  
Author(s):  
You‐Hua Chu ◽  
Thomas H. Chang ◽  
Gail M. Conway
Keyword(s):  
High Resolution ◽  
Planetary Nebula ◽  
X Ray

The Kinematics and Excitation of Molecular Hydrogen Emission in the Planetary Nebula BD +30o3639

1998 ◽  
Vol 498 (1) ◽  
pp. 267-277 ◽  
Author(s):  
D. L. Shupe ◽  
J. E. Larkin ◽  
R. A. Knop ◽  
L. Armus ◽  
K. Matthews ◽  
...  
Keyword(s):  
Planetary Nebula ◽  
Molecular Hydrogen ◽  
Hydrogen Emission

The High‐Excitation Planetary Nebula NGC 7662

1997 ◽  
Vol 491 (1) ◽  
pp. 242-253 ◽  
Author(s):  
Siek Hyung ◽  
Lawrence H. Aller
Keyword(s):  
Planetary Nebula ◽  
High Excitation ◽  
Ngc 7662

The Structure and Dynamics of the Proto–Planetary Nebula M1‐92

1998 ◽  
Vol 504 (2) ◽  
pp. 915-920 ◽  
Author(s):  
V. Bujarrabal ◽  
J. Alcolea ◽  
R. Neri
Keyword(s):  
Planetary Nebula ◽  
Structure And Dynamics
Sign in / Sign up

Export Citation Format

Share Document