Question
Question 1 What is the systematic name of the compound below? A. E-2-bromobut -2-ene B. Z-2-bromobut-2 -ene C. E-1,2-dimethyl-1-bromoethene D. Z-1,2-dimethyl-1-bromoethene [1 mark]
Answer
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Franklin
Professional · Tutor for 6 years
Answer
The correct option according to IUPAC nomenclature is A. 'E-2-bromobut-2-ene'.
Explanation
Systematic names of compounds are determined based on the set rules from International Union of Pure and Applied Chemistry (IUPAC). This question asks for an understanding of these rules to assign the correct name to the given compound.Now considering the systemic naming of the compound:The compound consists of a carbon bond with double bounding and a halogen substituent which is a bromine atom attached to it making it an alkene-bromine derivative.According to the IUPAC rules for naming alkenes with substituents, the alkene will be named based on the longest carbon chain. The double-bond position is indicated by the number in front of 'ene'. Additionally, the prefixes 'E' or 'Z' can be used to further specify the configuration of the molecules falling on each side of the double bond. In these prefixes, 'E' indicates that the greater prior groups are on the opposite sides of the double bond while 'Z' implies they are on the same side.Looking at the provided options, it's clear the primary part of the name should be '-but-2-ene' as the longest chain has 4 carbons, the double bond is located at the second position.Also, on each carbon included in the double bonding, the higher priority group (using CIP rules) is the bromine over the hydrogen and the methyl over the ethyl. As these higher priority groups are on the opposite side of the double bond, the configuration at this double bond should be 'E', and hence the name E-2-bromobut-2-ene.