7 Gosh, that was some ugly chemdraw, wasn't it. And not entirely accurate either, since the Lewis acid is definitely needed. (comment edited Oct 25 '18 at 21:29) edited Oct 25 '18 at 21:28 orthocresol♦ 43.4k77 gold badges136136 silver badges267267 bronze badges You were on right path; tert-butyl carbocation is quite stable$$\ldots$$ so stable that the acylium cation, which normally reacts as an electrophile itself, instead decomposes via decarbonylation (loss of stable carbon monoxide molecule). The t-butyl carbocation isn't as stable as the acylium cation (which is stabilised by resonance), but the difference is small enough that with the help of the non-reversibility of CO loss (which is removed from the mixture as a gas) and reduction of the steric strain (which is lower in t-butyl than in acylium), it is enough to make it the main reaction route (insteadinstead of a side route). You were on right path; tert-butyl carbocation is quite stable$$\ldots$$ so stable that the acylium cation, which normally reacts as an electrophile itself, instead decomposes via decarbonylation (loss of stable carbon monoxide molecule). The t-butyl carbocation isn't as stable as the acylium cation (which is stabilised by resonance), but the difference is small enough that with the help of the non-reversibility of CO loss (which is removed from the mixture as a gas) and reduction of the steric strain (which is lower in t-butyl than in acylium) it is enough to make it the main reaction route (instead of a side route). You were on right path; tert-butyl carbocation is quite stable$$\ldots$$ so stable that the acylium cation, which normally reacts as an electrophile itself, instead decomposes via decarbonylation (loss of stable carbon monoxide molecule). The t-butyl carbocation isn't as stable as the acylium cation (which is stabilised by resonance), but the difference is small enough that with the help of the non-reversibility of CO loss (which is removed from the mixture as a gas) and reduction of the steric strain (which is lower in t-butyl than in acylium), it is enough to make it the main reaction route instead of a side route. 6 added 128 characters in body edited Oct 25 '18 at 21:04 Mithoron 3,84688 gold badges2929 silver badges4747 bronze badges You were on right path; tert-butyl carbocation is quite stable$$\ldots$$ so stable that the acylium cation, which normally reacts as an electrophile itself, instead decomposes via decarbonylation (loss of stable carbon monoxide molecule). The t-butyl carbocation isn't as stable as the acylium cation (which is stabilised by resonance), but the difference is small enough that with the help of the non-reversibility of CO loss (which is removed from the mixture as a gas) and reduction of the steric strain (which is lower in t-butyl than in acylium) it is enough to make it the main reaction route (instead of a side route). You were on right path; tert-butyl carbocation is quite stable$$\ldots$$ so stable that the acylium cation, which normally reacts as an electrophile itself, instead decomposes via decarbonylation (loss of stable carbon monoxide molecule). The t-butyl carbocation isn't as stable as the acylium cation, but the difference is small enough that with the help of the non-reversibility of CO loss (which is removed from the mixture as a gas) and reduction of the steric strain (which is lower in t-butyl than in acylium) it is enough to make it the main reaction route (instead of a side route). You were on right path; tert-butyl carbocation is quite stable$$\ldots$$ so stable that the acylium cation, which normally reacts as an electrophile itself, instead decomposes via decarbonylation (loss of stable carbon monoxide molecule). The t-butyl carbocation isn't as stable as the acylium cation (which is stabilised by resonance), but the difference is small enough that with the help of the non-reversibility of CO loss (which is removed from the mixture as a gas) and reduction of the steric strain (which is lower in t-butyl than in acylium) it is enough to make it the main reaction route (instead of a side route). 5 added 9 characters in body edited Dec 10 '17 at 17:57 orthocresol♦ 43.4k77 gold badges136136 silver badges267267 bronze badges You were on right path; tert-butyl carbocation is quite stable$$\ldots$$ so stable that the acylium cation, which normally reacts withas an acylated compoundelectrophile itself, instead decomposes via decarbonylation (loss of stable carbon monoxide molecule). The t-butyl carbocation isn't as stable as the acylium cation, but the difference is small enough that with the help of the non-reversibility of CO loss (which is removed from the mixture as a gas) and reduction of the steric strain (which is lower in t-butyl than in acylium) it is enough to make it the main reaction route (instead of a side route). You were on right path; tert-butyl carbocation is quite stable$$\ldots$$ so stable that the acylium cation, which normally reacts with an acylated compound decomposes via decarbonylation (loss of stable carbon monoxide molecule). t-butyl isn't as stable as acylium cation, but the difference is small enough that with the help of the non-reversibility of CO loss (which is removed from the mixture as a gas) and reduction of the steric strain (which is lower in t-butyl than in acylium) it is enough to make it the main reaction route (instead of side route). You were on right path; tert-butyl carbocation is quite stable$$\ldots$$ so stable that the acylium cation, which normally reacts as an electrophile itself, instead decomposes via decarbonylation (loss of stable carbon monoxide molecule). The t-butyl carbocation isn't as stable as the acylium cation, but the difference is small enough that with the help of the non-reversibility of CO loss (which is removed from the mixture as a gas) and reduction of the steric strain (which is lower in t-butyl than in acylium) it is enough to make it the main reaction route (instead of a side route). 4 added 71 characters in body edited Dec 25 '16 at 17:02 orthocresol♦ 43.4k77 gold badges136136 silver badges267267 bronze badges 3 edited body edited Dec 25 '16 at 15:38 Mithoron 3,84688 gold badges2929 silver badges4747 bronze badges 2 I no like HyphenOverflow. edited Oct 5 '15 at 19:21 M.A.R. 7,0811313 gold badges5656 silver badges8282 bronze badges 1 answered Oct 5 '15 at 15:36 Mithoron 3,84688 gold badges2929 silver badges4747 bronze badges