Sciencemadness Discussion Board

selective alkylation of amines

rannyfash - 24-4-2012 at 08:09

(http://www.sciencemadness.org/talk/viewthread.php?tid=19851#...) "You totally lost me here! What exactly are you talking about? What procedure you are asking about and where is the reference? What does it have to do with this thread?" whoops sorry, i went off at a tangent, i want to make rhodamine b (chem teacher thinks i cant do it, i think i can) one of the reagents i need is 3-(diethylamino)phenol, i shouldve really asked originally about this but i wanted to work it out for myself, from what ive heard molar amounts of a haloalkane will give bad yield of diethyl, triethylammonium will be favoured as nitrogens lone pair becomes more reactive from what ive read, i read up about protective groups and there is a method used to introduce ethyl groups selectively, i cant find a link but it entailed reacting ethyl chloroformate with an amine or amide to form an ethyl carbamate, the ethyl carbamate was reduced to an ethyl group and co2, are there any other reactions to selectively introduce ethyl groups? found a link : http://syntheticfocus.com/synthesis-and-preparation-of-amine...
because of the molecules bulkyness only one can attach at a time, is this reaction unique or are there other methods of selectively introducing ethyl groups (i know its methyl in the link)

rannyfash - 24-4-2012 at 08:16

sorry i should have used the ducking search engine http://en.wikipedia.org/wiki/Eschweiler%E2%80%93Clarke_react... will ethanal react the same according to eschweiler clark?

Nicodem - 24-4-2012 at 11:05

Quote: Originally posted by rannyfash  
whoops sorry, i went off at a tangent, i want to make rhodamine b (chem teacher thinks i cant do it, i think i can) one of the reagents i need is 3-(diethylamino)phenol

What procedure will you be following? Give its reference, as it is pointless to discuss something nobody but you read. Besides, the article should give the reference for the preparation of m-(diethylamino)phenol unless it is commercially available.
Quote:
i shouldve really asked originally about this but i wanted to work it out for myself, from what ive heard molar amounts of a haloalkane will give bad yield of diethyl, triethylammonium will be favoured as nitrogens lone pair becomes more reactive from what ive read,

Where did you read that?
Have you even bothered doing a literature search for the syntheses of m-(diethylamino)phenol?
Quote:
i read up about protective groups and there is a method used to introduce ethyl groups selectively, i cant find a link but it entailed reacting ethyl chloroformate with an amine or amide to form an ethyl carbamate, the ethyl carbamate was reduced to an ethyl group and co2, are there any other reactions to selectively introduce ethyl groups?

The reduction of carbamates gives N-methylamines. Where did you see a formation of an N-ethylamine from a carbamate? Give the reference.
Quote:
sorry i should have used the ducking search engine http://en.wikipedia.org/wiki/Eschweiler%E2%80%93Clarke_react... will ethanal react the same according to eschweiler clark?

The Eschweiler-Clark reaction is an N-methylation reaction so it can not give the N-ethylated products. Perhaps you mean the Leuckart reaction? There have been topics with discussions, articles and references in regard to both reactions at this forum already, so UTFSE for more information.

Keep in mind that your substrate is an aniline (aromatic amine - not an aliphatic one!) and that it also has a phenolic hydroxy group. Its Pi-system is also highly nuclephilic.

Start using sentences, paragraphs and a spell checker if you want anyone to read your posts and take the time to help you. You only get as much respect as you show respect to others.

rannyfash - 24-4-2012 at 13:38

thank you, Im new so I am trying to adjust to the apparently strict grammar and other strange rules which I would not usually associate with science, I don't see how what I am using the reagent for is necessary, i don't really want to copy exactly what other people have written in their synthesise, it seems unimaginative and its not what i like in chemistry.

"Where did you read that?"
from previous posts here http://www.sciencemadness.org/talk/viewthread.php?tid=19851#...
"carbon is slightly electron donating, which makes substituted amines more nucleophilic" in my simulations i assumed that there was no change in reactivity of the nitrogen up the series of no. substitutes and it still gives a poor theoretical yield and thats without the extra reactivity(if you want i will make a thread on this too i am happy to),

i remember seeing the reduction of a carbamate with an ethyl R1 (http://en.wikipedia.org/wiki/Carbamate) group to an ethylamine, i cant remember which paper i read this on but the mechanisms made sense and i just assumed it would work, thank you for correcting my organic synth. knowledge and on hindsight i shouldn't stay up until 3am in the morning reading papers.

how could i use the leuckart reaction to achieve my final product?

[Edited on 25-4-2012 by rannyfash]

danielleB - 24-4-2012 at 21:50

Thanks for the post. It was really informational and can help me with my lessons.

rannyfash - 25-4-2012 at 05:55

i looked into the leuckart mechinism and it from what ive read on wikipedia i cant understand any feasible way that could obtain 3-diethylaminophenol from this reaction

Amy Winehouse - 25-4-2012 at 21:09

Quote:

thank you, Im new so I am trying to adjust to the apparently strict grammar and other strange rules which I would not usually associate with science, I don't see how what I am using the reagent for is necessary,


Lol don't worry man everyone gets jaded now and again, this is a good attitude to have, references are just helpful to see if other people have already tried to do whatever it is you are wondering, then if you are still curious you will be able to answer an even more profound question possibly.