The diethylamine also reacts with bromoethane - in the same two stages as before. The ammonia removes a hydrogen ion from the triethylammonium ion to leave a tertiary amine - triethylamine. A tertiary amine is one which has three alkyl groups attached to the nitrogen. The final stage!
The triethylamine reacts with bromoethane to give tetraethylammonium bromide - a quaternary ammonium salt one in which all four hydrogens have been replaced by alkyl groups. It is much, much easier to work it out if you need to, provided you understand the mechanisms for the reactions.
Preparation of Amines
You can explore the mechanisms for the various stages of the reaction by following this link. This will lead you to several pages in the mechanism section of this site. If all you want to do is make some sense of the above reactions, it would probably pay you to just read the parts of those pages concerned with primary halogenoalkanes like bromoethane. Whatever you do, you get a mixture of all of the products including the various amines and their salts shown on this page.
To get mainly the quaternary ammonium salt, you can use a large excess of bromoethane.
Substituted amine synthesis by amination (alkylation)
If you look at the reactions going on, each one needs additional bromoethane. If you provide enough, then the chances are that the reaction will go to completion, given enough time. On the other hand, if you use a very large excess of ammonia, the chances are always greatest that a bromoethane molecule will hit an ammonia molecule rather than one of the amines being formed. That will help to prevent the formation of secondary etc amines - although it won't stop it entirely. Nitriles are compounds containing the -CN group, and can be reduced in various ways.
Two possible methods are described here. One possible reducing agent is lithium tetrahydridoaluminate III - often just called lithium tetrahydridoaluminate or lithium aluminium hydride. The nitrile reacts with the lithium tetrahydridoaluminate in solution in ethoxyethane diethyl ether, or just "ether" followed by treatment of the product of that reaction with a dilute acid. Notice that this is a simplified equation - perfectly acceptable to UK A level examiners. However, NaBH 4 isn't a strong enough reducing agent to reduce nitriles.
The carbon-nitrogen triple bond in a nitrile can also be reduced by reaction with hydrogen gas in the presence of a variety of metal catalysts. The reaction will take place at a raised temperature and pressure. Skip to main content. Title Efficient synthesis of secondary amines by selective alkylation of primary amines. Authors Kyung Woon Jung. Abstract A method for selective mono-N-alkylation of primary amines to produce secondary amines that are substantially free of overalkylated tertiary amines and quaternary ammonium salts, under mild reaction conditions without the necessity of protecting groups.
Recommended Citation Jung, Kyung Woon, "Efficient synthesis of secondary amines by selective alkylation of primary amines" Gratifyingly, all stages of this chemistry were compatible with transfer to a polymer supported protocol by the use of polymer supported triphenylphosphine 19 at the phosphine stage to give the polymer supported iminophosphorane 10 as shown in Scheme 2.
Polymer supported phosphine 9 can be regenerated by the reduction of polymer supported phosphine oxide 11 with trichlorosilane. Abstract Secondary amines are obtained in moderate-good yields by reduction of crude imines prepared from N-alkyltriethoxyiminophosphoranes and aldehydes via the aza-Wittig reaction. Experimental General Unless otherwise stated, all solvents and reagents were purchased from commercial suppliers and used without further purification. References Cadogan, J. Leyshon, L. Abstract A new one-pot procedure for transforming primary alkyl bromides into the corresponding imines via the Staudinger reaction has been developed.
Scheme 1. Experimental Synthesis of N-Benzyl-N- phenylmethylidene amine 1. Synthesis of N-Nonyl-N- phenylmethylidene amine 6. Phenyl-N- 1-phenylethylidene methanamine 4 : The compound was not isolated. References Staudinger, H. Liebigs Ann. Tetrahedron Lett. Synthesis and references cited therein. Ran,, B. Synthesis Hemming, M. Bevan, C. Loukou, S.
- preparation of amines.
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- "Efficient synthesis of secondary amines by selective alkylation of pri" by Kyung Woon Jung?
- SYNTHESIS OF SOME SECONDARY AMINE DERIVATIVES BEARING A HETEROARYL FRAGMENT;
Patel, D. Renaudeau Synlett Abstract This paper presents a high yielding one-pot solution phase and polymer supported synthesis of a range of primary and secondary amines starting from azides and aldehydes. Scheme 2.
Preparation of Amines
References and Notes For reviews, see: North, M. For examples, see: a Suwa, T. Synlett , 4, ; b Bae, J. Synthetic Commun. Tetrahedron , 53 48 , ; e Brunel, J. Synlett , ; f De Kimpe, N.
Synthesis , For reviews, see: Enders, D. Tetrahedron: Asymmetry , 8 12 , ; Bloch, R. For recent examples, see: a Chen, G-M.
- Alkylation of ammonia.
- Synthesis of Amines - Chemistry LibreTexts.
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- Secondary amines.
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For recent examples, see: Byrne, J. For reviews, see: Brown, R. For recent examples, see: a Bao, M. T; Hermkens, P.
Tetrahedron , 54, ; Rueter, J. Koziara, A. Synthesis , ; Katritzky, A. Holletz, T. Synthesis , ; Schoetzau, T. Afonso, C. Sampath Kumar, H. Synlett , Tetrahedron , 54, ; b Knapp, S. For a review, see: Gololobov, Y. Tetrahedron , 48, For reviews, see Wahmhoff, H.
Heterocyclic Chem. Hart, D.