mike888 Posted June 24, 2018 Posted June 24, 2018 Hi I am trying to make an ester from primary alcohol and carboxylic acid that contain multiple double bonds. Fischer–Speier esterification is not working since the addition of sulfuric acid causes the acid to react with double bonds. appreciate any advise
BabcockHall Posted June 27, 2018 Posted June 27, 2018 Esters can be made using dicyclohexylcarbodiimide and catalytic DMAP. Another method is to use oxalyl chloride to form the acid chloride. We have used the latter method successfully in the presence of a double bond.
hypervalent_iodine Posted June 27, 2018 Posted June 27, 2018 I have also made esters fairly easily by reaction with Cs2CO3, the carboxylic acid and iodoalkanes.
BabcockHall Posted June 28, 2018 Posted June 28, 2018 (edited) Did the double bond isomerize in a stereochemical (cis-trans) sense; did it move in a regiochemical sense; or did it do something else? Edited June 28, 2018 by BabcockHall
mike888 Posted July 8, 2018 Author Posted July 8, 2018 (edited) On 6/27/2018 at 9:28 AM, BabcockHall said: Esters can be made using dicyclohexylcarbodiimide and catalytic DMAP. Another method is to use oxalyl chloride to form the acid chloride. We have used the latter method successfully in the presence of a double bond. thank you Bad for the reply. I have already tried DCC/DMAP in Ch2Cl2. I am still trying to find out if I succeeded or not. I am trying to make an ester from Retinoic acid with 3,5-Di-tert-butyl-4-hydroxy-benzyl alcohol (BHT-OH). Retinoic acid is notorious in flipping around its double bound and giving up isomers. at this stage I am more interested to put A+B together and get the ester. with steglich reaction I easily get the retinoic acid react with DCC, but it seems reaction does not give the ester I am looking for. stirring the mixture overnight at RT with drying tube attached produced two compounds along with starting material. one seems to be retinoic-DMAP, the other unknown. I am monitoring the reaction using HPLC and soon I will switch to LC/MS to figure out what is going on here many thanks for your reply mike Edited July 8, 2018 by mike888
BabcockHall Posted July 10, 2018 Posted July 10, 2018 (edited) Which hydroxyl group do you want to react? I don't know but I wonder if you would need to protect the other one. What mole ratio of DMAP are you using? Edited July 10, 2018 by BabcockHall
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