4. Lipid peroxidation can lead to a bewildering number of different products. This is illustrated by an interesting JACS paper published by Salomon et al. J. Am. Chem. Soc. 2004, 126, 5699-5708. This paper investigates products formed from free radical reactions with Linoleic Acid (LA, 1). Both questions below refer to the above paper, please read it first. (a) Write down a reasonable mechanism for the decomposition of compound 9-HP-12 HODE (6) (compound is shown in Scheme 1 in the paper) to the corresponding hydroxy alkenal. Hint: This is a Hock-type cleavage. Please do not omit steps. Nomenclature hint - in case you forgot: An alkenal is a compound that has a C=C double bond and an aldehyde group., (b) An alternative mechanism for the formation of aldehyde fragments from unsaturated fatty acids involves formation of a hydroperoxide followed by formation of a four- membered ring, a so-called dioxetane. Provide a detailed step-by-step mechanism for the formation of two aldehyde cleavage products from the starting fatty acid LA(1) via the dioxetane pathway. Hint: See Scheme 2 in the paper; while the Scheme is very helpful, you will need to provide arrows and additional intermediates.