Unusual behaviour of Lithium aluminium hydride




Conversion of amides into amines by reduction (RCONH2 =RCH2NH2)
Amides are organic compounds with chemical formula RCONH2 in which R refers to the hydrocarbon chainand can either be aromatic or aliphatic. Therefore amides are derivative of carboxylic acids where hydroxyl (-OH) is replaced by amino group (-NH2)  or they are organic compounds in which amino groups are attached to carbonyl groups of carboxylic acids or they are conjugate base of anion(the anion H2N-) or organic amine(an anion R2N-). They are reduced by LiAlH4 / lithium aluminum hydride (reduction by hydride transfer {-H}), usually LiAlH4 is a powerful reducing agent and reduces ketones, esters, aldehydes, carboxylic acids, nitriles and amide quite rapidly and on hydrolysis gives alcohol as the product. In this case it is different; LiAlH4 reduces amide to amine instead of alcohol. Reduction is the gain of electron and decreasing of oxidation number or it is a chemical reaction in which hydrogen is added to the molecule or oxygen is removed  from the molecule.  Reaction in this reduction proceeds as indicated below;
RCONH2(amide) =  RCH2NH2 (amine)+Water (H2O)                     
      (In presence of   ether, Lithium aluminum hydride (LiAlH4) and Water (H2O))                                       
The effect of amide reduction is to convert amide’s carbonyl (-C=O) group to (-CH2) group. This kind of reaction is specific for amides but not other carboxylic derivatives. For this type of reaction it can be noted that it imitates the characteristics of reactions of Clammansen Reduction and Wolf-kishner Reduction which convert carbonyl group (-C=O) to methylene (-CH2).



Comments

Post a Comment

Popular posts from this blog

How to write a Forensic Case Study: Murder of Junko Furuta

Image
Photo of Junko Furuta  For one to score high marks in a Forensic Case Study, one must  adhere to the following: Background of the case: This section contains details about the crime. It includes; the reasons for committing the offense, the conditions which the crime was committed, the circumstances of the crime scene and clear identification of the suspect(s) and the victim(s). One should ensure that the information in this part gives a precise idea of what the case is all about.   Pick and Write an article on Iwriter Website Evidence: This encompasses the piece of evidence found at the crime scene. The evidence should be described in details, that is, ways in which the evidence was collected, processed and preserved.   Forensic Tests: The tests should be two or more that were used to analyze the evidence. The science or theory of instrumentation used must be described fully.   Results: This consists of a detailed explanation of the forensic tests and the data inter
Read more

Roles of Sodium Carbonate when Extracting Caffeine from Tea Leaves

Image
A student failed to add sodium carbonate (Na 2 CO 3 ) when extracting caffeine from tea leaves with hot water. Though, high yield of caffeine was produced. The crystals melted at temperatures between 202  and 214 degree  Celsius. Explain. This happened because sodium carbonate did not interfere with the caffeine content of the tea leaves. Sodium carbonate (which is a base) deprotonates the phenolic hydroxyl group (-OH) (acidic) of tannins rendering them anionic. Hence, making them highly soluble in water, but parsimoniously soluble in methylene chloride. So, if sodium carbonate is not added when extracting caffeine with hot water, the extracted caffeine would also contain tannins. Additionally, sodium carbonate is added during the extraction to keep caffeine (an alkaloid which is an organic base)  in a free base form. It prevents caffeine from reacting with available acid available, which may lead to the formation cation. It reacts with a phenolic hydroxyl group
Read more

What is Hartmann Dispersion Formula?

Image
  Hartmann dispersion formula is a semi-empirical formula. It is also referred to as Cornu Hartmann formula. It relates refractive index (n) with the wavelength (λ). It is given by:  n (λ)= X + Y/( λ-Z)............................................................Equation 1  X, Y, and Z are empirical constants while n (λ) is the refractive index of a material of light of wavelength λ. The constants derived as follows: Z= [(n 1 -n 2 )/ (n 2 -n 3 ) λ 1 (λ 2 - λ 3 ) - λ 3 - λ 3 (λ 1 - λ 2 )]/ [(n1-n2)/ (n2-n3) (λ2- λ 3 )-(λ1- λ 2 )]-....................................................................................Equation 2  Y= (n 1 -n 2 )/ [1/ (λ1-Z)-(1/ (λ2-Z)…………………………Equation 3  X=n 1 -B/ (λ1-Z)…………………………………………...Equation 4  Hartmann dispersion formula is applied in the measurements of spectra wavelengths taken on a prism instruments.  Constant Z is the spectrometer optical function. In the laboratory, it usually measured by lab technicians fo
Read more