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If you Google "largest known cycloalkane", you will find this result:

enter image description here

For context, there has been discussions on "largest known alkane". There is a related chem.SE question. There is also a scientific paper on it. The paper says that the longest linear alkane is $\ce{C59H120}$. OTOH, the Wikipedia article for cycloalkane mentions that the larger cycloalkanes, with more than 20 carbon atoms are typically called cycloparaffins. So, there has to be a known "cycloparaffin" with highest number of carbon atoms.

The above result came from a random HW-QnA site. From where does the result come from?

Question: Does the largest known cycloalkane really contain 288 carbon atoms? If not, how many carbon atoms are there in the largest cycloalkane that has been actually observed and isolated?

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According to Makromol. Chem., Rapid Commun. 1985, 6 (3), 203–208[1], Kwang Sup Lee and Gerhard Wegner, attempting the synthesis and study of $n>100$, $\ce{C_nH_{2n}}$ cyclo-alkanes and linear alkanes, were successfully able to synthesize a linear alkane of $\ce{C384H770}$ and cycloalkanes with 288 carbons ($\ce{C288H576}$)

Linear alkanes up to $\ce{C384H770}$, (2k; M = 5378) and cycloalkanes up to $\ce{C288H576}$(3g; M = 4040) were prepared by this strategy.

A brief method of preparation is as follows:

The strategy of the synthesis of long chain linear and cyclic alkanes was developed starting from the work of Schill et al. who had shown that the oligomers obtained by oxidative coupling of 1 following Eq. (1) can be separated by adsorption chromatography. \begin{align} \ce{\underset{\textbf{1}}{HC#C-(CH2)20-C#CH} ->[Cu^2+] \\ \underset{\textbf{2}}{HC#C-(CH2)20-C#C-\left[C#C-(CH2)20-C#C\right]_m-H}} \\ \end{align}

A similar strategy was used to synthesize the cycloalkanes as well.

The cyclic oligomers were synthesized by the same reaction according to Eq. (2) under conditions of high dilution of the terminal diacetylene

enter image description here

Finally, the linear and cyclic oligomers were hydrogenated over a Pd/C-catalyst in a conventional manner to obtain the analytically pure alkanes.

As for the assignment question, I was able to link it to a introductory exercise in Organic Chemistry by Janice Gorzynski Smith.2.

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Reference

  1. Kwang Sup Lee, Gerhard Wegner, "Linear and cyclic alkanes ($\ce{C_nH_{2n+2}, C_nH_{2n}}$) with $n > 100$. Synthesis and evidence for chain-folding," Makromol. Chem., Rapid Commun. 1985, 6 (3), 203–208 (https://doi.org/10.1002/marc.1985.030060316)
  2. Janice Gorzynski Smith, Organic Chemistry, Sixth Edition, McGraw-Hill book Company Inc.;2020, ISBN: 978-0-07-066720-4
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  • $\begingroup$ A) Perhaps an accidental error, but for me, the link behind the introductory exercise aims to show Organic Chemistry by Robin Charles Burrel published by McGraw Hill in 1936, but stops midway with the note "No preview available". Maybe google.co.in differs in this from google.com? B) I don't have Janice Smith's book in the shelf, but if the content still supports your argument, I recommend to link to the publisher's entry to the current 6th edition by 2020 (incl. an updated ISBN13) here. $\endgroup$ – Buttonwood May 30 at 20:14
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    $\begingroup$ @Buttonwood, seems to be an error in google books. The cover of the preview shows Janice gorzynski smith as the author. I've updated the publisher information, but the preview still works for me. I've removed the preview and added the actual image of the question. $\endgroup$ – Safdar Faisal Jun 4 at 10:48

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