Emil Fischer — Unequalled Classicist, Master of Organic Chemistry Research, and Inspired Trailblazer of Biological Chemistry

ChemInform ◽  
2003 ◽  
Vol 34 (12) ◽  
Author(s):  
Horst Kunz
Keyword(s):  
Organic Chemistry ◽  
Biological Chemistry ◽  
Chemistry Research

Some comments on the development of free radical chemistry

1984 ◽  
Vol 39 (1) ◽  
pp. 105-124 ◽  
Keyword(s):  
Organic Chemistry ◽  
Free Radicals ◽  
Free Radical ◽  
Early Development ◽  
Room Temperature ◽  
Single Atom ◽  
Biological Chemistry ◽  
Personal Recollection ◽  
The Subject ◽  
Free Radical Chemistry

For many years, an introduction to the chemistry of free radicals has formed an essential part of University chemistry curricula and the subject is of wide relevance to both industrial and biological chemistry, yet its development occurred, with surprising rapidity, less than fifty years ago. It is the aim of this article to give a personal recollection of the circumstances which led to the recognition and early development of this branch of chemistry. From the early days of the last century ‘radicals’ had been defined by chemists as ‘groups of atoms which together behave as a single atom’ and organic chemistry had been regarded as the chemistry of ‘compound radicals’. But with the proof that such simple elements as hydrogen, oxygen and nitrogen exist as binary molecules (H 2 , O 2 , N 2 ) and not as atoms, the possible existence at room temperature, in gases or solutions, of free atoms or radicals was deemed to be unlikely by most chemists of a century ago.

scholarly journals Ring Contraction Reactions of a Non-Benzenoid Aromatic Cation and a Neutral Homoaromatic System into Benzene Derivatives

2021 ◽  
Author(s):  
Demelza Lyons ◽  
An Huy Dinh ◽  
Nhan Nu Hong Ton ◽  
Reece Crocker ◽  
Binh Khanh Mai ◽  
...  
Keyword(s):  
Organic Chemistry ◽  
Benzene Ring ◽  
Benzene Derivatives ◽  
Ring Contraction ◽  
Chemistry Research ◽  
Synthetic Utility ◽  
Aromatic Ions ◽  
Benzyl Halides ◽  
Tropylium Salts ◽  
Ring Contraction Reaction

Aromaticity is one of the most intriguing concepts in organic chemistry. Simple and extended benzenoid aromatic systems have been very well established in undergraduate textbooks, and there are also mentions of non-benzenoid aromatic structures such as cyclopropenium, cyclopentadienide and cycloheptatrienylium (tropylium) ions. However, the structural relationship and the comparison of stabilization energy of such aromatic ions to benzene ring have been rarely studied and remained an underexplored area of advanced organic chemistry research. To contribute some insights into this topic, we focused on the chemical transformation, namely a ring contraction reaction, of the tropylium ion to benzene ring in this work. With an approach combining computational studies with experimental reactions, we also aim to turn this transformation into a synthetically useful tool. Indeed, this work led to the development of a new synthetic protocol, which involved an oxidative ring-contraction of tropylium ion, to formally introduce the phenyl ring onto a range of organic structures. Furthermore, the homoaromatic cycloheptatrienyl precursors of tropylium salts used in these reactions can also be rearranged to valuable benzhydryl or benzyl halides, enriching the synthetic utility of this ring-contraction protocol.

Sign in / Sign up

Export Citation Format

Share Document