Question

CH₃CH₂COCl IUPAC name is:

• A. Propanoyl Chloride
• B. Ethanoyl Chloride
• C. Acetyl Chloride
• D. Chloroethane

Answer 1

The correct option is A

Propanoyl Chloride

Solution: (A)

CH₃CH₂COCl has three carbon atoms in the parent chain and chloroformyl group(-COCl). Thus, the name of the compound is Propanoyl chloride.

IUPAC(international union of pure and applied chemistry) decided on some rules to name the compounds so that the discussion and study all around the world become easy.

The following are the rules of IUPAC for the naming of the compounds:

• Identify the longest carbon chain. This chain is called the parent chain.
• Identify all of the substituents (groups appending from the parent chain).
• Number the carbons of the parent chain from the end that gives the substituents the lowest numbers. When comparing a series of numbers, the series that is the "lowest" is the one that contains the lowest number at the occasion of the first difference. If two or more side chains are in equivalent positions, assign the lowest number to the one which will come first in the name.
• If the same substituent occurs more than once, the location of each point on which the substituent occurs is given. In addition, the number of times the substituent group occurs is indicated by a prefix (di, tri, tetra, etc.).
• If there are two or more different substituents they are listed in alphabetical order using the base name (ignore the prefixes). The only prefix which is used when putting the substituents in alphabetical order is iso as in isopropyl or isobutyl. The prefixes sec- and tert- are not used in determining alphabetical order except when compared with each other.
• If chains of equal length are competing for selection as the parent chain, then the choice goes in series to:
  a) the chain which has the greatest number of side chains.
  b) the chain whose substituents have the lowest- numbers.
  c) the chain having the greatest number of carbon atoms in the smaller side chain.
  d)the chain having the least branched side chains.
• A cyclic (ring) hydrocarbon is designated by the prefix cyclo- which appears directly in front of the base name.

In summary, the name of the compound is written out with the substituents in alphabetical order followed by the base name (derived from the number of carbons in the parent chain). Commas are used between numbers and dashes are used between letters and numbers. There are no spaces in the name.

For example,

The explanation for the incorrect options:

Options B and C:

The functional group in Ethanoyl Chloride/Acetyl chloride is carboxylic acid chloride.

Its formula is ${\mathrm{CH}}_3\mathrm{COCl}$

The structural formula of Ethanoyl Chloride/Acetyl chloride is as follows;

Option D:
The molecular formula of Chloroethane is ${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Cl}$

The structural formula of chloroethane:

Therefore the correct option is Option A.