A carbonyl compound $$$\mathbf{X}$$$ will react with $$$\mathrm{HCN}$$$ in the presence of $$$\mathrm{NaCN}$$$ to make a compound with $$$M_{\mathrm{r}}$$$ 85. Compound $$$\mathbf{X}$$$ does not react with Fehling's reagent. What is $$$\mathbf{X}$$$ ?

butanal

butanone

propanal

propanone

Chemistry

IGCSE&ALevel

CAIE

Exam No：9701_s17_qp_12 Year：2017 Question No：20

Answer:

Knowledge points:

17.1.1.1 the oxidation of primary alcohols using acidified and distillation to produce aldehydes

17.1.1.2 the oxidation of secondary alcohols using acidified or acidified and distillation to produce ketones

17.1.2.1 the reduction of aldehydes and ketones, using to produce alcohols

17.1.2.2 the reaction of aldehydes and ketones with HCN, KCN as catalyst, and heat to produce hydroxynitriles exemplified by ethanal and propanone

17.1.3 describe the mechanism of the nucleophilic addition reactions of hydrogen cyanide with aldehydes and ketones in 17.1.2(b)

17.1.4 describe the use of 2,4-dinitrophenylhydrazine (2,4-DNPH reagent) to detect the presence of carbonyl compounds

17.1.5 deduce the nature (aldehyde or ketone) of an unknown carbonyl compound from the results of simple tests (Fehling’s and Tollens’ reagents; ease of oxidation)

17.1.6 deduce the presence of a – group in an aldehyde or ketone, , from its reaction with alkaline (aq) to form a yellow precipitate of tri-iodomethane and an ion,

A carbonyl compound $$\(\mathbf{X}\)$$ will react with $$\(\mathrm{HCN}\)$$ in the presence of $$\(\mathrm{NaCN}\)$$ to make a compound with $$\(M_{\mathrm{r}}\)$$ 85. Compound $$\(\mathbf{X}\)$$ does not react with Fehling's reagent. What is $$\(\mathbf{X}\)$$ ?

Answer:

Knowledge points:

Solution:

A carbonyl compound $$\(\mathbf{X}\)$$ will react with $$\(\mathrm{HCN}\)$$ in the presence of $$\(\mathrm{NaCN}\)$$ to make a compound with $$\(M_{\mathrm{r}}\)$$ 85. Compound $$\(\mathbf{X}\)$$ does not react with Fehling's reagent. What is $$\(\mathbf{X}\)$$ ?

Answer:

Knowledge points:

Solution:

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