Alcohols, Halogenoalkanes

Chapters 2.8-2.10: alcohols, halogenoalkanes, mechanisms and spectra
Consolidation questions 1. Give the names of the two primary alcohols with the molecular formula C4H10O. butan-1-ol 2-methyl propan-1-ol

2. Write the equation, using state symbols, for the reaction of ethanol with sodium.
CH3CH2OH(l) + Na(s) CH3CH2O-Na+(alc) + ½ H2(g)

3. Name the organic product above.
Sodium ethoxide

4. Give the names and structural formulae for the two possible products of the reaction of methanol with sodium dichromate(VI).
HCHO methanal HCOOH methanoic acid
(Partial oxidation) (Full oxidation)

5. For the products above give a test that would confirm the functional group
Add Brady’s reagent
Draw structural formulae for the four isomers with molecular formula C4H9Br.
A CH3CH2CH2CH2Br 1-bromopropane
B CH3CH2CHBrCH3 2-bromopropane
C CH3CHBr(CH3)CH3 2-bromo-2-methylpropane
D CH3CH(CH3)CH2Br 1-bromo-2-methylpropane

7. Which of the halogenoalkanes in the previous question will react fastest with aqueous silver nitrate? Give a reason for your answer.
C, as it forms a tertiary carbocation, which is the most stable intermediate.

8. An unknown halogenoalkane , with molecular formula C2H5X reacts with hot aqueous silver nitrate to give a yellow ppt. a) identify the halogen
Yellow ppt is AgI, so the halogen is
Peak at 57 is the molecular ion less one hydrogen: C3H5O+ (the H may be lost from any carbon: you do not need to be able to predict which one will lose it)

Peak at 29 could be CH3-CH2+ OR else CHO+.
(These two could be distinguished by very accurate and precise high resolution mass spectrometry, which is routinely achievable on modern magnetic sector instruments. In this case, the precise masses of the C, H and O in each fragment are added up and the masses compared with experimental mass. This works because mass of O is not exactly 16 mass units etc.)

b. Suggest how the mass spectrum for propanone would differ
Both are C3H6O, so have same molecular ion peak at m/e = 58.
Propanone will have fragment ion peak at m/e = 48 (CH3CO+), which is absent from propanal mass spectrum.

14. Which of the following are green house gases? chlorine, chloromethane, nitrogen dioxide, argon, ammonia
The 3 which are underlined can absorb infrared radiation as their vibrations give rise to oscillating dipoles.

15. Classify the following reactions: a) CH3CH 3 + Br2 → CH3CH2Br + HBr Free radical substitution b) CH2=CH2 + Br2 → CH2BrCH2Br Electrophilic