Hi sanimmo,
I like SGIII's idea. Here's an expansion of it that might be more suitable for your situation, where I suspect the URLs are longer that ths used in SG's example.
Here the menus (Column A of Main) contain only the names of the sites or pages you want to link to. These names and the links associated with them are listed as a lookup table (Links), which may be placed on another sheet, if desired.
Note the two links to openstreetmap.org. The first will open a map page—either the last one visited from this computer or the 'home' location in England, depending whether there's a cookie on your machine recording the last visit.
The second is to a specific location—44.5298° N 110.3192° W—and is rather long to include as an item on a popup menu, similar to what would be required to open the specific page containing the safety data for a specific chemical on your list.
All Data on Links is directly entered, either via the keycoard, or by copy/paste in the case of the urls.
Main contains the formula shown, entered into B2, then filled down to the rest of the cells in column B.
Main::B2: IF(LEN(A2)<1,"",VLOOKUP(A2,Links::A:B,2,FALSE))
The core part of the formula is shown in bold. The rest is a switch used to prevent calculation (and an error message) in rows where column A is empty.
Regards,
Barry
PS: For the curious, here's the link to the OSM at Yellowstone:
www.openstreetmap.org/search?query=44.5298%2C-110.3192#map=10/44.5298/-110.3192
B