Concept explainers
(a)
Interpretation:
The explaination for the observation that although biacetyl and
Concept introduction:
The dipole moment of a molecule is the measure of the polarity of the
(b)
Interpretation:
The explaination for the observation that
Concept introduction:
The UV-visible spectroscopy involves the excitation of the electrons in the molecule. In the
(c)
Interpretation:
The explanation for the observation that compound A has much weaker IR carbonyl absorption than compound B is to be stated.
Concept introduction:
Spectroscopy method is used to identify the structure of the molecule. It is based on the interactions between matter and
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Organic Chemistry
- Describe the characteristic infrared absorption frequencies that would allow you to distinguish between the following pairs of compounds. (a) cyclohex-2-enone and cyclohex-3-enone (b) cyclohexanol and cyclohexanonearrow_forwardThe following compound, 2-hydroxycycloheptatrienone, does not give all the usual carbonyl group reactions. (i) Explain this apparent anomaly. Furthermore, explain the significant difference between the relative stability of this compound and its 3- and 4-hydroxy isomers. (ii) What would you expect to be the influence of adding (a) a nitro group as a substituent on the 7-membered ring or (b) an alkyl group, on the degree of aromaticity of the above compound. (iii) Based on your understanding of the hydrogen bonding concept, which isomer would you expect to have a higher m.p, (assuming they are both solids) between 2- and 4- hydroxycycloheptatrienone? Explain your choice.arrow_forward(a) Account for the following :(i) Propanal is more reactive than propanone towards nucleophilic reagents.(ii) Electrophilic substitution in benzoic acid takes place at meta position.(iii) Carboxylic acids do not give characteristic reactions of carbonyl group.(b) Give simple chemical test to distinguish between the following pairs of compounds:(i) Acetophenone and benzaldehyde(ii) Benzoic acid and ethylbenzoate.arrow_forward
- (a) The Friedel-Crafts reaction of benzene with 2-chloro-3-methylbutane in the presence of AlCl3 occurs with a carbocation rearrangement. Give mechanistic explanation and the product formed. (b) Predict the product(s) will be formed from the following reactions: (i) Bromination of p-methylbenzoic acid (ii) Sulphonation of m-bromoanisole (iii) Friedel-craft acylation of o-bromonitrobenzenearrow_forwardCompound C has the molecular formula C5H8O. The IR, 1H, 13C, and DEPT NMR spectra of this compound are shown below. (a) Calculate the double bond equivalent of compound C and briefly explain what the values obtains represents. Interpret the IR spectrum. (b) Based on the information provided, determine the structure of compound D.arrow_forward(c) A series of dialkyl ethers react with excess hydrogen bromide, with the following results. Analyze the ether in each case and write out the complete chemical equations. (1) Ether gives a mixture of bromocyclopentane and 1-bromoethane. (ii) Another ether gives one mole of 1,5-dibromopentane per mole of ether.arrow_forward
- (a) Give a plausible explanation for each one of the following :(i) There are two – NH2 groups in semicarbazide. However, only one such group is involved in the formation of semicarbazones.(ii) Cyclohexanone forms cyanohydrin in good yield but 2, 4, 6-trimethylcyclohexanone does not.(b) An organic compound with molecular formula C9H10O forms 2, 4, – DNP derivative, reduces Tollens’ reagent and undergoes Cannizzaro’s reaction. On vigorous oxidation it gives 1, 2-benzene-di- carboxylic acid. Identify the compound.arrow_forwardExplain the following observations :(i) The boiling point of ethanol is higher than that of methoxymethane.(ii) Phenol is more acidic than ethanol.(iii) o- and p-nitrophenols are more acidic than phenol.arrow_forwardGive reasons: (i) Bond length of C = O in carboxylic acids is slightly larger than C = O bond length in carbonyl compounds. (ii) There are two –NH2 groups in semicarbazide. However, only one –NH2 group is involved in the formation of semicarbazones. (iii) Benzoic acid is less soluble in water than acetic acid. (iv) Formic acid is a stronger acid than acetic acid.arrow_forward
- 2. DEDUCE THE STRUCTURE FOR EACH COMPOUND WITH THE INDICATED MOLECULAR FORMULA AND THE 1H-NMR AND IR SPECTRA PROVIDED. (a) Formula: C4H8O2arrow_forward(a) Give chemical tests to distinguish between :(i) Propanol and propanone (ii) Benzaldehyde and acetophenone(b) Arrange the following compounds in an increasing order of their property as indicated :(i) Acetaldehyde, Acetone, Methyl tert-butyl ketone (reactivity towards HCN)(ii) Benzoic acid, 3,4-Dinitrobenzoic acid, 4-Methoxybenzoic acid (acid strength)(iii) CH3CH2CH (Br) COOH, CH3CH (Br) CH2COOH, (CH3)2CHCOOH (acid strength)arrow_forward(a) The IR spectrum below shows the important absorption bands for compound A (C7H1402). Its 'H NMR spectrum shows only singlets at &H 1.3, 2.3, 3.9 and 8.5 with the integration ratio of 9:2:2:1. Using all the spectral data, deduce the structure of compound A. 100 50- 2898 2986 1718 3446 1150 0- 4000 3000 2000 1500 1000 500 wavenumber 5. Transmittancearrow_forward
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