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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Akutni on January 14, 2023, 12:13:00 PM

Title: Product of this Sn2 reaction
Post by: Akutni on January 14, 2023, 12:13:00 PM: Are the products of this reaction correct?
Title: Re: Product of this Sn2 reaction
Post by: Babcock_Hall on January 14, 2023, 12:54:52 PM: Would you please provide your thinking first?
Title: Re: Product of this Sn2 reaction
Post by: Akutni on January 14, 2023, 02:03:23 PM: Quote from: Babcock_Hall on January 14, 2023, 12:54:52 PM
Would you please provide your thinking first?
I think the chlorine is exchanged by the cyanide group. And –OH group reacts with –C≡N group forming the aforesaid product.
Title: Re: Product of this Sn2 reaction
Post by: Babcock_Hall on January 14, 2023, 03:16:40 PM: That is a very reasonable idea. IMO the only thing left to check is the stereochemical outcome. I suggest assigning the configurations.
Title: Re: Product of this Sn2 reaction
Post by: rolnor on January 18, 2023, 02:45:32 PM: This does not look like a stable product, if the reaction is done in water, the ester is more likely formed.
Title: Re: Product of this Sn2 reaction
Post by: Vidya on January 20, 2023, 06:58:45 AM: Quote from: Akutni on January 14, 2023, 02:03:23 PM
Quote from: Babcock_Hall on January 14, 2023, 12:54:52 PM
Would you please provide your thinking first?
I think the chlorine is exchanged by the cyanide group. And –OH group reacts with –C≡N group forming the aforesaid product.
Your idea is right.
Chlorine is the better leaving group and OH is very poor leaving group so CN- which is very strong nucleophile reacts by SN2 mechanism and finally carbon of the CN group is attacked by lone pairs of oxygen and during this mechanism protonation and deprotonation takes place to give that cyclic ring.
Title: Re: Product of this Sn2 reaction
Post by: rolnor on January 20, 2023, 01:44:07 PM: Sorry, the cyclic ester, a lactone is formed.
Title: Re: Product of this Sn2 reaction
Post by: Babcock_Hall on January 23, 2023, 11:36:05 AM: Did the question specify the solvent?
Title: Re: Product of this Sn2 reaction
Post by: rolnor on January 27, 2023, 04:04:18 PM: It could also form the open-chain hydroxy carboxamide, that is more likely if the reraction solution is very concentrated and a closed flask is used.
Title: Re: Product of this Sn2 reaction
Post by: rolnor on January 29, 2023, 05:40:12 AM: It could be a trick question, cyaniode is a poor Sn2 nucleophile and you might get elimination... Or you get the open chain hyedroxy nitrile. Chloride is a very poor leaving group so this reaction is very slow.
Title: Re: Product of this Sn2 reaction
Post by: Akutni on February 03, 2023, 06:08:38 AM: Quote from: Babcock_Hall on January 23, 2023, 11:36:05 AM
Did the question specify the solvent?
No, but it should be Sn2 reaction according to the instructions.
Title: Re: Product of this Sn2 reaction
Post by: Babcock_Hall on February 03, 2023, 11:39:31 AM: Rolnor made a good point that in water an imine might hydrolyze. I take a slightly different view regarding the nucleophilicity of cyanide ion. Its value of n_MeOH against methyl iodide is 6.7, which is comparable to hydroxyl amine.
Title: Re: Product of this Sn2 reaction
Post by: rolnor on February 07, 2023, 03:57:07 PM: I think it depends om solvent, I have not worked with cyanide but I have colleagues who has and they are not to positive about it. But I can be wrong. Chloride is a poor leaving group anyway, the reaction is probably not practical. A secondary chloride is poorer Sn2 electrophile still.
Title: Re: Product of this Sn2 reaction
Post by: rolnor on February 07, 2023, 03:58:31 PM: There is really no reason why the cyanide would rect further than forming a nitrile, nitriles do not react with alcohols under these conditions.