I have a database of broken links on chem.SE. Would anyone like to take a stab at replacing the links and better describing the links (if needed) so that if they break again it's easier found?

If this is a noble cause, I will work on getting my database into a better format and post them all here (the work below was tedious.) If anyone knows a way to better format what I posted below so that it's easier to read, I would love to see that.

  1. Question: Conversion atom to another Anchor text: ACS Reagent grade, Dead link: https://pubs.acs.org/reagents/index.html

  2. Question: How can carbon dioxide be converted into carbon and oxygen?, Anchor text: http://www.rsc.org/chemistryworld/news/2008/january/03010801.asp, Dead link: https://www.chemistryworld.com/chemistryworld/news/2008/january/03010801.asp

  3. Question: What do the different grades of chemicals mean?, Anchor text: table, Dead link: http://www.sigmaaldrich.com/technical-service-home/product-portfolio.html

  4. Question: What do the different grades of chemicals mean?, Anchor text: ACS Reagent grade, Dead link: https://pubs.acs.org/reagents/index.html

  5. Question: Adding hydrogens to multiple pdb files using Openbabel GUI software, Anchor text: here, Dead link: http://openbabel.org/docs/current/Command-line_tools/babel.html

  6. Question: How do I type a simple chemical equation in Microsoft Word?, Anchor text: Shortcut for typing arrows of chemical equation in Word 2007 and above, Dead link: https://cpgupta1201.wordpress.com/2018/09/21/quickest-way-to-type-chemical-reaction-chemical-equation-reaction-arrows-in-word-2007-above/

  7. Question: EZ-Water - Fraud or breakthrough?, Anchor text: quack medicine, Dead link: https://articles.mercola.com/sites/articles/archive/2013/08/18/exclusion-zone-water.aspx

  8. Question: How do I extract cyanide from apple seeds?, Anchor text: U.S. National Library of Medicine, Dead link: http://chem.sis.nlm.nih.gov/chemidplus/rn/29883-15-6

  9. Question: How do I extract cyanide from apple seeds?, Anchor text: U.S. National Library of Medicine, Dead link: http://chem.sis.nlm.nih.gov/chemidplus/rn/29883-15-6

WayBack Machine is a good resource for determining what was once hosted at a particular url in the event that the URL and describing text are too ambiguous. If it would be helpful to have the HTTP response codes for each as well, let me know.

Some work could also be done in finding any links and making sure they're properly described in case of them breaking in the future, but that (like properly describing image uploads), is a tremendous effort.

  • 2
    $\begingroup$ To the readers: Is there an easy way to mass-fix links?, $\endgroup$ Commented Apr 12 at 12:20
  • 3
    $\begingroup$ Without a complete rewrite of questions and answers I think switching to archive links closest to publication is the best way to go. Content could have changed along with the link. $\endgroup$ Commented Apr 13 at 12:52
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    $\begingroup$ Yep, go to the wayback machine..... $\endgroup$
    – Buck Thorn Mod
    Commented Apr 16 at 10:29
  • $\begingroup$ How important do you feel it is to retain links to vendors (in view of this post)? $\endgroup$
    – Buck Thorn Mod
    Commented Apr 20 at 8:39
  • $\begingroup$ See also: meta.stackexchange.com/questions/16807/… and plenty more on meta. $\endgroup$
    – Buck Thorn Mod
    Commented Apr 20 at 10:43

1 Answer 1


You can copy-paste a table created in a spreadsheet or text editor using " | " as entry separator, which evaluates into a markup table here (you need to leave spaces around the bar so that it formats properly). This should save some editorial effort.

Note also there is some duplication in your table.

A search might help find some dead links if it's a systematic problem. From the page Nilay linked to it appears staff sometimes gets involved in updating links, perhaps if they know what to look for. See also this post.

Some dead links are probably not worth updating, particularly to vendor catalogs. Links to vendors are prone to rot when products are discontinued or catalogs reorganized. If links to dead urls are forwarded to updated pages (usually product pages) updating is not as crucial. For instance, Sigma-Aldrich seems to have a system to prevent dead ends (example), but not all vendors do (probably few do). Rotten links to vendors can often be substituted with CAS numbers or other equivalent info. Sometimes rot can cause a post to lose meaning, such as when (now nonexistent) products are compared, in which case a post may not be salvageable and may be worth deleting. The key is to attempt to retain the original intent of the original post. Absent a descriptive anchor text potentially much of a posts' meaning can be lost. Perhaps this should be our focus.

I searched for links to sigmaldrich.com and the result is a mixed bag. Links to MSDSs are a common victim (such as this MSDS linked from here). In the case of a particular vendor MSDS where specific content is important, key information and with it much of a posts' meaning may be lost when the link dies. MSDSs are otherwise fairly easy to find, for instance the US library of congress provides what is likely a reliable and static repository (but access seems iffy). As an effort updating MSDS links is noble but therefore imo of little importance.

It should be in the best interest of those who created a post (if still active on the site) to keep links updated. A standard comment left under the post might help spread the effort. We might also want to have a new or updated post about best practices. I do remember reading somewhere the suggestion that a minimum reliance on links and external content is best. Some suggest not just leaving comments but downvoting posts with dead links. Seems harsh, let individuals decide.


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