chemistry

Sydnone

Sydnone is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Sydnone rather than just read about it. In short: Sydnones are mesoionic heterocyclic chemical compounds possessing a C5-oxygenated 1,2,3-oxadiazole core, named after the city of Sydney, Australia. Like other mesoionic compounds they are dipolar, possessing both positive and negative charges which are delocalized across the ring.

Key takeaways

Sydnone belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sydnone to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sydnone from memory before moving on to harder problems.

Reference excerpt

Sydnones are mesoionic heterocyclic chemical compounds possessing a C5-oxygenated 1,2,3-oxadiazole core, named after the city of Sydney, Australia. Like other mesoionic compounds they are dipolar, possessing both positive and negative charges which are delocalized across the ring.

Discovery N-phenylsydnone was first prepared in 1935 by John Campbell Earl and Alan W. Mackney by cyclodehydration of N-Nitroso-N-phenylglycine with acetic anhydride. Later work showed that this could be applied fairly generally to the nitrosamines of N-substituted amino acids. The parent compound sydnone is not synthetically accessible and may not exist.

Chemical structure Sydnones have the following resonance structures. The exocyclic oxygen atom (O6) has a significant negative charge.

Recent computational studies have indicated that sydnones and other similar mesoionic compounds are nonaromatic, "though well-stabilized in two separate regions by electron and charge delocalization."

Examples Cefanone (Cephanone) Ipramidil 3-Thiomorpholino-sydnonimine U.S. patent 4,332,801 The reaction between methyl 3-benzyl-sydnone-4-acetate and diphenylacetylene is described in Ex1 of GB 1387306 gives an analog of Bufezolac. Synthesis and Biological Evaluation of Coumarinyl Sydnone Derivatives.

Related compounds A sydnone imine in which the keto group of sydnone (=O) has been replaced with an imino (=NH) group can be found as a substructure in the stimulant drugs feprosidnine and mesocarb.

See also Chemical compounds with unusual names Montréalone Münchnone Sydnone imine

References

S. Wiechmann; T. Freese; M. H. H. Drafz; E. G. Hübner; J. C. Namyslo; M. Nieger; A. Schmidt (2014). "Sydnone anions and abnormal N-heterocyclic carbenes of O-ethylsydnones. Characterizations, calculations and catalyses". Chem. Commun. 50 (80): 11822–11824. doi:10.1039/C4CC05461J. hdl:10138/224668. PMID 25156208. Claude V. Greco; Wayne H. Nyberg; C. C. Cheng (1962). "Synthesis of Sydnones and Sydnone Imines". Journal of Medicinal Chemistry. 5 (4): 861–865. doi:10.1021/jm01239a022. PMID 14056419. Wilson Baker; W. D. Ollis (1957). "Meso-ionic compounds". Quarterly Reviews, Chemical Society. 11: 15–30. doi:10.1039/QR9571100015. S2CID 96888271. Joseph Fugger; Jack M. Tien; I. Moyer Hunsberger (1955). "The Preparation of Substituted Hydrazines. I. Alkylhydrazines via Alkylsydnones". J. Am. Chem. Soc. 77 (7): 1843–1848. doi:10.1021/ja01612a039. Jack M. Tien; I. Moyer Hunsberger (1955). "The Preparation of Substituted Hydrazines. II.1 3-Pyridylhydrazine via the Phototropic N-(3-Pyridyl)-sydnone". J. Am. Chem. Soc. 77 (24): 6604–6607. doi:10.1021/ja01629a052. 88, 178 (1961); Jack M. Tien; I. Moyer Hunsberger (1961). "Sydnones. III. Preparation and Interconversion of Mercurated Derivatives of N-(3-Pyridyl)-sydnone1-3a". J. Am. Chem. Soc. 83 (1): 178–182. doi:10.1021/ja01462a035. Alan R. Katritzky (1955). Chem. Ind.: 521. {{cite journal}}: Missing or empty |title= (help), (); Alexander Lawson; D. H. Miles (1959). "Some new mesoionic compounds". J. Chem. Soc.: 2865–2871. doi:10.1039/JR9590002865. J. Ogilvie; V. K. Miyamoto; Thomas C. Bruice (1961). "A Kinetic Study of the Reaction of a "Meso-ionic" Compound (Dehydrodithizone) with Haloacetates". J. Am. Chem. Soc. 83 (11): 2493–2495. doi:10.1021/ja01472a017. LEMONT B. KIER, LAURETTA E. FOX, D. DHAWAN & I. W. WATERS (1962). "A New Class of Central Nervous System Stimulants". Nature. 195 (4843): 817–818. Bibcode:1962Natur.195..817K. doi:10.1038/195817a0. PMID 14455827. S2CID 1683698.{{cite journal}}: CS1 maint: multiple names: authors list (link)

External links IUPAC Goldbook entry Dictionary of Organic Compounds

Illustrations

Worked examples

Example 1 — a first encounter with Sydnone

Start with the simplest possible case. Write down what Sydnone claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sydnone before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sydnone ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sydnone

In research: Sydnone appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Sydnone in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Sydnone is common in secondary-school and first-year university syllabi. It links to neighbouring topics Lactones, Mesoionic compounds, Oxadiazoles, so understanding it makes those chapters shorter.
In everyday life: Look for Sydnone outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Sydnone in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sydnone means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Sydnone out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sydnone in simple terms?

Why does Sydnone matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sydnone?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sydnone.