1 The Diels-Alder reaction is a conjugate addition reaction of a conjugated diene to an alkene (the dienophile) to produce a cyclohexene. 2  The simplest example is the reaction of 1,3-butadiene with ethene to form cyclohexene:3  The analogous reaction of 1,3-butadiene with ethyne to form 1,4-cyclohexadiene is also known: Due to the high degree of regio-and stereoselectivity (due to the concerted mechanism), the Diels-Alder reaction is a very powerful reaction and is widely used in synthetic organic chemistry.
Best Answer: Buyers have up 7 days to pay for an item before you as a seller can open an unpaid item case with ebay. They have a whole process they ask that sellers follow: Buyers automatically enter into a legally binding contract to purchase the item from the seller if they win an online auction or use the Buy It Now feature.
One of the many formats under which you can create your listing on eBay is called the Good Til Cancelled (GTC) listing. Under this format, your listing will be created for a duration of 30 days. It will be a fixed price listing and at the end of the 30 day period, your listing will automatically get renewed and list again. This continues to happen after every 30 day period till such time that the seller cancels the listing. Many sellers initially confused a GTC listing with a Fixed Price 30 listing.