The yellow with a white eye has a number of possibilities. The color varies slightly from plant to plant, and more importantly from photograph to photograph. Unless the photo is taken with a proper white balance setting and is digitally processed with a color profile, the colors will vary slightly and make it impossible to match exactly.
Anyway, my guess is Kinchin Yellow. It is marketed by Bahama Bay, and they are widely available. I hope this helps.
I looked up pictured of the Kinchin Yellow Hibiscus and the flower seems to be a more pale yellow than mine. Mine is more of a golden/darker yellow. I don't know if it helps, but mine seems to stay more compact than my pink and orange ones, which are more of tall and bushy.
I also bought the yellow and pink ones at the same time from the same nursery & they were somewhat similar in size, except the pink one was a little taller My yellow one likes to grow outward rather than upward, and the pink one love to grow upward and outward. Here is a picture of them about a week after I bought them. Also, the one with yellow flowers has about 2 to 2/12 inch long heart shaped leaves while the pink and orange one have 3 1/2 to 4 inch heart shaped leaves.
The 1st pic was taken about 1 week after I bought these Hibiscus. The 2nd pic was taken today after I brought them inside due to the cold weather we are expected to have overnight. See have much taller the pink one grew? It is taller than the mantle while the yellow one is more compact and reaches only 1/2 way up to the mantle. The 3rd picture is the Orange Hibiscus in August. It has since grow upward at least another foot or so.
You can talk to the people in your local nursery where you bought the plants and ask them where they usually get their hibiscus plants from. Bahama Bay is a large supplier and they have Kinchin's Yellow.
Maji, I tried to do that. An employee sold them to me in June, but when I was at the nursery a few weeks ago, I talked to the owner. I explained about purchasing 1 pink and 1 yellow flowering Hibiscus back in June and how I did not know the names of the plants. She looked at me like I was stupid. I asked her if she knew what the names might be and she shook her head like I was stupid for asking lol I even showed her where they were located in the nursery when I bought them. That didn't help either. I will probably just wait until next spring and go back and see if they have the same Hibiscus plants at the nursery, or at least a name of the supplier on a tag or pot.