Condesned final deck prt 2 Flashcards
Homologous series?
Organic compounds which have the same functional group and general formula
Each member differs by CH2
What can you call an alpiphatic chain with a non aromatic ring?
Alicyclic
What’s heterolytic bond fission?
Bond breaks unevenly, with one of the bonded pairs receiving both electrons A cation (+) and an anion (-) are formed
What’s homolytic fission?
Bond breaks evenly, and each bonding pair receives an electron
Two neutral radicals are formed ( have an unpaired electron)
What occurs in initiation stage?
Free radicals are produced
Cl2 = (UV light) 2Cl# = photodissocation
So has been split homolytically
#= radical symbol
What occurs in propagation stage?
Cl# + CH4 = #CH3 + HCl #CH3 + Cl2 = CH3Cl + Cl#
Termination reactions?
Cl# + #CH3 = CH3Cl Cl# +Cl# = Cl2 #CH3 + #CH3 = C2H6
What’s a sigma bond?
Forms when 2 s orbitals overlap in a straight line, this gives the highest possible electron density between the 2 nuclei, this is a single covalent bond
The high electron density between the nuclei means there is a strong electrostatic attraction between the nuclei and shared pair of electrons
Strongest type of covalent bond
Draw these by having 2 spheres with a dot in the middle for a nucleus, and draw them overlapping in a diablo shape
What’s a pi bond?
Formed from the sideways overlap of 2 adjacent p orbitals
It’s bellow and above the molecular axis, because the pi orbitals that overlap are dumbbell shaped
Pi bonds are weaker than sigma bonds because electron density spread above and bellow the nuclei, so weaker electro static attraction between nuclei and shared pair of electrons, so break easier than sigma bonds
Draw this by having 2 dumbell shapes with curved lines connecting each top of the dumbell
Which forms 2 dots with a curved pi bond above and bellow
How do you produce an Alkane from an Alkene?
Add hydrogen gas
Ni catalyst and temperature around 150 degrees
What’s the mechanism of halogens being reacting with alkenes to form dihaloalkanes?
Draw the alkene eg ethane, and draw the halogen eg bromine molecule near the double bond, the closer bromine atom will have a delta positive charge, as electrons have been repelled away by double bond, making the other Br molecule delta negative
Draw curly arrow from double bond to Delta + Br
Draw curly arrow from bond between Br’s to the delta negative Br
Draw the double bond now split to a single bond, and one C has a Br molecule attached, the other C will have a positive charge, and draw the other Br molecule with a negative charge and a lone pair with a curly arrow to the positively charged carbon
Draw the final dihaloalkane
How do you make ethanol from Ethene?
Add water as steam at 300 degrees
60-70 atm
Phosphoric acid catalyst
when a hydrogen halide reacts with an unsymmetrical alkene how do you know which is the major and minor product?
Major product is more stable so the halide ion will bind to the Carbon which is bonded directly to the most other Hydrogens( least amount of carbons)
Minor product is less stable, so the halide ion will bind to the Carbon which is bonded directly to less hydrogens(more amount of Carbons)
How would you draw a pi and sigma bond together?
Have the carbon atoms with a spherical Sigma bond between them (hot dog) Have the (bun) pi bonds above them, with 2 hydrogen s coming of each Carbon
Whats the reaction mechanism for nucleophillic substitution reaction?
Draw the halolkane with a delta positve charge on Carbon, and delta negative on halogen
draw an OH- ion with a lone pair near it, and a curly arrow going from lone pair to the delta positive carbon
this forms an alcohol and the halogen forms with a lone pair and a negative charge
Equations for how ozone forms?
O2 = 2O# radicals due to UV light
O2 + O# = O3
How do CFC’s destroy the Ozone?
Chlorine free radicals are formed when the Cl-Cl bonds in CFC’s are broken down by UV light
eg. CF2Cl2 = (UV) CF2Cl + Cl#
Then Cl# + O3 = O2 + ClO#
ClO# + O = O2 + Cl#
So overall reaction is O3 + O = 2O2 and Cl# is the catalyst
Equations for NO# breaking down ozone?
NO# + O3 = NO2 + O2
NO2 + O = NO# + O2
What is special about the OH peak in a carboxylic acid?
Much broader
How would you draw Bromine reacting with Benzene with aid of AlCl3 catalyst?
Draw the bromine molecule with one end delta + and one delta -
Draw Benzene
Write AlCl3
Have a curly arrow going from Br-Br bond to AlCl3, and a curly arrow from the delocalised electrons from ring to delta + Br
This produces benzene ring where delocalised ring as hole in it, is positively charged and has Br and a H visibly bonded to it
Also produces AlCl3Br-
Finally forms Bromobenzene + HBr + AlCl3
General formula for an alkylation Fridel craft reaction?
C6H6 + R-X =(AlCl3 catalyst + reflux) C6H5R + HX
R= alkane part of halogen X= Halogen
General formula for an acylation reaction?
C6H6 + RCOCl = ( AlCl3 catalsyt + Relfux) C6H5COR + HCl
COR = Carbon doubled bonded to Oxygen, then bonded to a Carbon Chain (R)
What’s produced when Phenol is Nitrated with Dilute Nitric acid?
2-nitrophenol or 4-nitrophenol and water
What happens if you react Phenol with NaOH?
Sodium phenoxide (benezene ring bonded to O- which is bonded to Na+) is formed and water
Describe the reaction mechanism of the reducing agent NaBH4, dissolved in water with methanol reducing an aldehyde to a primary alcohol, or a Ketone to a secondary alcohol and what type of reaction is it?
It’s a nucleophillic addition reaction
NaBH4 provides a H- ion with a lone pair, the carbonyls groups carbon will have a delta positive charge, and the oxygen will have a delta negative charge
H- ion will have a curly arrow going from the lone pair to the delta + carbon, and there will be a curly arrow going from the double bond in the carbonyl group to the delta negative oxygen
This will form a carbon bonded to the 2 other original elements, a hydrogen and a single bonded to a negative oxygen with a lone pair
Now draw a water molecule, with 2 delta positive hydrogens, and a delta negative oxygen
Draw a curly arrow going from lone pair on oxygen to a delta positive hydrogen, and a curly arrow going from the bond between the delta postive hydrogen, and the delta negative oxygen to the oxygen
This will form an OH- ion, and either a primary or secondary alcohol
Describe how hydrogen cyanide will react with aldehydes or ketones to form hydroxynitriles and what type of reaction is it?
Nucleophillic reaction
Hydrogen cyanide is a weak acid so HCN will dissociate into H+ and CN- ions
Draw N triple bonded to C(-) and draw the aldehyde or ketone with a delta negative oxygen double bonded to the delta positive carbon
Draw a curly arrow going from the lone pair on Carbon to the delta positive carbon, and also a curly arrow from the double bond in the carbonyl group, to the delta negative oxygen
This will form a carbon bonded to it’s 2 original elements, a carbon triple bonded to a Nitrogen, and single bonded to an oxygen with a lone pair and a negative charge.
The lone pair on the oxygen will have a curly arrow going to the H+ remaining from the dissociation of the hydrogen cyanide, making it so the carbon is now bonded to an OH group, which is the hydroxynitrile
What is an acyl chloride, and how do you name them?
Same as carboxylic acid, except replace the OH group with a Cl, name them by putting at the end “oyl chloride”
How do you make an acyl chloride?
React a carboxylic acid with SOCl2, to produce an acyl chloride, SO2 and HCl
What happens when acyl chlorides react with cold water?
Produce a carboxylic acid and HCl
What happens when acyl chlorides react with alcohols?
Produce an ester and HCl
What happens when acyl chlorides react with Ammonia?
Primary amide and HCl
What happens when acyl chlorides react with amines?
Secondary amide and HCl
What type of reaction are all the reaction with acyl chloride?
Nucleophillic addition-elimination
All reactions are with the chlorine
Reaction of acyl chlorides with phenol?
An ester and HCl
Reversible reaction
How do you make an ester and water from alcohols and carboxylic acids?
Heat them together in the presence of sulfuric acid catalyst
It’s an esterfication reaction
Reversible reaction, so need to heat under reflux and use fractional distillation to separate the ester from other compounds
How do you name an ester?
Look at the alkyl group that came from the alcohol (the bit single bonded to the oxygen) and add yl to end of it, eg ethane = ethyl
Look at bit from carboxylic acid (bit bonded to the carbon double bonded to the oxygen (include that carbon aswel)) and find the name of it and replace oic acid with oate, eg ethanoic acid = ethanoate
Put the 2 parts together, eg = ethyl ethanoate
2 ways esters are hydrolysed to form alcohols?
Acid hydrolysis:
Reflux the ester with sulfuric acid, and H2O, will produce a carboxylic acid and an alcohol
Base hydrolysis:
Reflux the ester with NaOH, to get a carboxylate salt (instead of H in OH group of carboxylic acid, it’s a Na) and an alcohol
How can you make aliphatic amines, and the second step you have to do aswell?
Heating a haloalkane with an excess of ammonia dissolved in ethanol
Will produce a mixture of primary, secondary, tertiary amines, and quaternary ammonium salts, as more than one hydrogen is likely to undergo nucleophillic substiution
So have to separate products using fractional distilation
How can you make aromatic amines?
Heat a mixture of a nitro compound, tin metal, and concentrated HCl under reflux which creates a salt
To get the aromatic amine, have to then add NaOH
What do you react to create a polyamide?
A dicarboxylic acid (COOH group at both ends) and a diamine (NH2 group at both ends)
What do you react to create a polyester?
A dicarboxylic acid (COOH group at both ends) and a diol (OH group at both ends)
Describe the nucleophillic addition reaction mechanism of Carbonyl compounds with Hydrogen Cyanide to extend the carbon chain?
Draw the carbonyl compound with a delta positive carbon double bonded to a delta negative Oxygen. And draw the cyanide ion (C-(lone pair) triple bonded to N)
Draw a curly arrow from the double bond in the carbonyl group to the delta negative oxygen, and draw a curly arrow from the lone pair on the carbon to the delta positive carbon
This will form the carbon in the carbonyl compound single bonded to an O- and bonded to another carob which is triple bonded to a Nitrogen
The H+ ion will then react with the O- to form an OH group
A HYDROXYNITRILE IS FORMED, the carbon from the carbonyl group is now single bonded to an OH group and single bonded to a carbon which is triple bonded to a nitrogen
What can you add to Nitriles or Hydroxynitriles to reduce them to primary amines?
Lithium Aluminium hydride (LiAlH4)
Dilute acid
Or Sodium metal and ethanol
How can you remove any water soluble impurities from a compound?
Use separation, if the product is insoluble and want to remove any impurities that do dissolve in water
Once the reaction is complete, the mixture is poured into a separating funnel, and water is added
The funnel is shaken and then allowed to settle, the organic layer is less dense that the aqueous layer so should float on top
Any water soluble impurities should have dissolved in the lower aqueous layer, so can run off funnel into only left with the organic layer
The organic layer will now contain trace amounts of water, so it has to be dried
Add an anhydrous salt such as magnesium sulphate, which will act as a drying agent
Then filter the product to remove the solid drying agent
Describe how organic solids can be purified by recrystallisation?
Very hot solvent is added to the impure solid, until it just dissolves
This provides a saturated solution ( maximum amount of solid dissolved)
The solution is left to cool down slowly. Crystals of the product form as it cools, the impurities stay in solution, as they are in much smaller quantities so they take much longer to crystalise out
The crystals are removed via filtration under reduced pressure and washed with ice cold solvent
They are dried, leaving with you product much cooler than the orginal
How do you test for carboxylic acids?
Add sodium carbonate, The solution will fizz, the CO2 gas produced will turn limewater cloudy
Why is tetramethylsilane (Si(CH3)4) used as a standard for NMR (it’s value is 0)?
It produces a single absorption peak in both types of NMR because all it’s carbon and Hydrogen nuclei are in the same environment
It’s absorption peak is lower than everything else
What’s the number of neighbouring hydrogens if the peak is split into a doublet (2 peaks) a triplet (3 peaks) or a quartet (4 peaks)?
N + 1 rule
Doublet = one hydrogen on the neighbouring carbon Triplet = 2 hydrogens on the neighbouring carbon Quartet = 3 hydrogens on the neighbouring carbon
How can OH and NH protons be indentified by proton exchange using D2O?
The chemical shift produced by protons attached to O or N is very variable
Run 2 spectra of the molecule, one with Dueterium oxide added (D2O)
If an OH or NH proton is present, it will swap with deuterium and the peak will dissapear as deuterium dosen’t aborb the radiowave
Can compare spectra and work which ones are the NH and OH peaks
