6.2 Nitogen Compounds, Polymers And Synthesis Flashcards
What are amines?
Organic chemicals where one or more of the hydrogen atoms on ammonia have been replaced by alkyl chains
What are the 3 types of amines?
Primary- one hydrogen atom on ammonia has been substituted. The structural formula can be summarised as RNH2 where R is an alkyl chain
Secondary- two hydrogen atoms have been substituted. The structural formula can summarised as RNHR’ where R and R’ are alkyl chains euchre may be the same or different
Tertiary-all three hydrogen atoms have been substituted. The structural formula can summaries as RNR’R’’ where R, R’ and R’’ can be the same or different hydrocarbon groups.
How do you name primary amines?
-determine the root by the longest hydrocarbon chain
-add any prefixes for other groups. Finally add the suffix amine
How do you name secondary amines?
-determine the root by naming the two alkyl chains
-add any prefixes for additional groups and write them in alphabetical order
-add the suffix ‘amine’
-secondary amines often have the prefix N-
How do you name tertiary amines?
-determine the root by naming the three alkyl chains
-add the prefix N,N-
Are amines bases?
Yes
-when an amine reacts with an acid it accepts a proton, a covalent bond is formed by the nitrogen atom donating its lone pair of electrons to the proton to form a dative covalent bond
-as well as this amines react with dilute acids e.g. HCl (aq) to form an alkylammonium salt
What is the general formula for amino acids?
RCH(NH2)COOH
How do you form aliphatic amines?
-using a sealed tube a haloalkane, excess ammonia and ethanol are heated together to make an amine
-the haloalkane will undergo nucleophilic addition in a 2 stage process
1- the ammonia reacts with the haloalkane to make an ammonium salt
2-an additional ammonia molecule reacts to form the propylamine product and ammonium chloride salt
-it is a reversible reaction so excess ammonia will increase the yield of the desired product
-additional substitutions on the hydrogen atoms on the nitrogen can occur
-when preparing amines by this method there is always a mixture of the products produced
How do you prepare aromatic amines?
-nitroarenes (e.g. nitrobenzene) can be reduced to produce an amine
-the reducing agent is made in situ by using a mixture of tin and concentrated hydrochloric acid
-the reaction occurs at reflux at 100 degrees Celsius
-after about half an hour a strong alkali is added, this undergoes a neutralisation reaction to remove excess hydrochloric acid and produce the amine
-separating the amine is a multi-stage process it includes: steam distillation, solvent extraction and further distillation
When do zwitterions form?
They form ay the isoelectric point, which is the pH at which the overall charge of the molecule is zero
What is the zwitterionic form of an amino acid?
-when the amine group has a positive charge (NH3+) and the carboxylic group has a negative charge (COO-)
What is the zwitterionic form of an amino acid?
-when the amine group has a positive charge (NH3+) and the carboxylic group has a negative charge (COO-)
