Tweeted twitter.com/StackChemistry/status/741788313493868544 occurred Jun 12 '16 at 0:24 Bumped by Community user occurred Jun 8 '16 at 23:21 4 changed wrong information edited May 9 '16 at 22:35 Daipayan Mukherjee 21911 silver badge1313 bronze badges Given this compound in an acidic medium, what would get protonated first? Would the double bond not get protonated preferentially, since oxygen is more electronegative than carbon and less willing to donate an electron pair for protonation? I checked the $$\mathrm{p}K_\mathrm{a}$$ value for the conjugate acid of an aldehyde, and it was around -10, which is pretty low; this suggests that the aldehyde would have a very low basicity. Also ethenecarbocation had a $$\mathrm{p}K_\mathrm{a}$$ value of around 43-3. Going by this information does it not make sense for a double bond to get protonated first? On the other hand, the oxonium ion is resonance stabilised, which would indicate that it is protonated in preference to the double bonds. Which reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates? Given this compound in an acidic medium, what would get protonated first? Would the double bond not get protonated preferentially, since oxygen is more electronegative than carbon and less willing to donate an electron pair for protonation? I checked the $$\mathrm{p}K_\mathrm{a}$$ value for the conjugate acid of an aldehyde, and it was around -10, which is pretty low; this suggests that the aldehyde would have a very low basicity. Also ethene had a $$\mathrm{p}K_\mathrm{a}$$ value of around 43. Going by this information does it not make sense for a double bond to get protonated first? On the other hand, the oxonium ion is resonance stabilised, which would indicate that it is protonated in preference to the double bonds. Which reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates? Given this compound in an acidic medium, what would get protonated first? Would the double bond not get protonated preferentially, since oxygen is more electronegative than carbon and less willing to donate an electron pair for protonation? I checked the $$\mathrm{p}K_\mathrm{a}$$ value for the conjugate acid of an aldehyde, and it was around -10, which is pretty low; this suggests that the aldehyde would have a very low basicity. Also carbocation had a $$\mathrm{p}K_\mathrm{a}$$ value of around -3. Going by this information does it not make sense for a double bond to get protonated first? On the other hand, the oxonium ion is resonance stabilised, which would indicate that it is protonated in preference to the double bonds. Which reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates? 3 deleted 38 characters in body edited May 9 '16 at 22:20 orthocresol♦ 42.8k77 gold badges133133 silver badges263263 bronze badges Given this compound in an acidic medium, what would get protonated first? Would not the double bond not get protonated preferentially, since oxygen is more electronegative than carbon and less willing to donate an electron pair for protonation? I checked the pka$$\mathrm{p}K_\mathrm{a}$$ value for the conjugate acid of an aldehyde, and it was around -10-10, which is pretty low, and hencelow; this suggests that the aldehyde would have a very low basicitylow basicity. Also alkene (ethene)ethene had a pka$$\mathrm{p}K_\mathrm{a}$$ value of around 43. Going by this information does it not make sense for a double bond to get protonated first? ON the other hand, the oxonium ion, in this case is resonance stabilised, which would indicate that it is protonated in preference to the double bonds. On the other hand, the oxonium ion is resonance stabilised, which would indicate that it is protonated in preference to the double bonds. Which of these reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates? Which reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates? Given this compound in an acidic medium, what would get protonated first? Would not the double bond get protonated preferentially, since oxygen is more electronegative than carbon and less willing to donate an electron pair for protonation? I checked the pka value for the conjugate acid of aldehyde, and it was around -10, which is pretty low, and hence suggests that aldehyde would have a very low basicity Also alkene (ethene) had a pka value of around 43. Going by this information does it not make sense for a double bond to get protonated first? ON the other hand, the oxonium ion, in this case is resonance stabilised, which would indicate that it is protonated in preference to the double bonds. Which of these reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates? Given this compound in an acidic medium, what would get protonated first? Would the double bond not get protonated preferentially, since oxygen is more electronegative than carbon and less willing to donate an electron pair for protonation? I checked the $$\mathrm{p}K_\mathrm{a}$$ value for the conjugate acid of an aldehyde, and it was around -10, which is pretty low; this suggests that the aldehyde would have a very low basicity. Also ethene had a $$\mathrm{p}K_\mathrm{a}$$ value of around 43. Going by this information does it not make sense for a double bond to get protonated first? On the other hand, the oxonium ion is resonance stabilised, which would indicate that it is protonated in preference to the double bonds. Which reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates? 2 deleted 4 characters in body; edited tags edited May 9 '16 at 22:09 Mithoron 3,85888 gold badges2929 silver badges4747 bronze badges Given this compound in an acidic medium  , what would get protonated first? Would not the double bond get protonated preferentially, since oxygen is more electronegative than carbon and less willing to donate an electron pair for protonation? I checked the pka value for the conjugate acid of aldehyde,and and it was around -10,which which is pretty low, and hence suggests that aldehyde would have a very low basicity Also alkene (ethene) had a pka value of around 43. Going by this information does it not make sense for a double bond to get protnatedprotonated first? ON the other hand, the oxonium ion,in in this case is resonance stabilised  , which would indicate that it is protonated in preference to the double bonds. Which of these reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates? Given this compound in an acidic medium  , what would get protonated first? Would not the double bond get protonated preferentially, since oxygen is more electronegative than carbon and less willing to donate an electron pair for protonation? I checked the pka value for the conjugate acid of aldehyde,and it was around -10,which is pretty low, and hence suggests that aldehyde would have a very low basicity Also alkene (ethene) had a pka value of around 43. Going by this information does it not make sense for a double bond to get protnated first? ON the other hand, the oxonium ion,in this case is resonance stabilised  , which would indicate that it is protonated in preference to the double bonds. Which of these reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates? Given this compound in an acidic medium, what would get protonated first? Would not the double bond get protonated preferentially, since oxygen is more electronegative than carbon and less willing to donate an electron pair for protonation? I checked the pka value for the conjugate acid of aldehyde, and it was around -10, which is pretty low, and hence suggests that aldehyde would have a very low basicity Also alkene (ethene) had a pka value of around 43. Going by this information does it not make sense for a double bond to get protonated first? ON the other hand, the oxonium ion, in this case is resonance stabilised, which would indicate that it is protonated in preference to the double bonds. Which of these reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates? 1 asked May 9 '16 at 21:53 Daipayan Mukherjee 21911 silver badge1313 bronze badges