Question

For the molecule whose condensed structural formula is given below, decide if cis-trans isomers are possible. If they are, enter the name of the cis isomer in the first box and the name of the trans isomer in the second box. If cis-trans isomers are not possible, enter the name of the compound in the first box and leave the second box blank. Do not attempt to put "cis" or "trans" in italics.

CH3CH2CH
name of cis isomer or molecule:_______.
name of trans isomer or none:_______.

Answer 1

The molecule CH3CH2CH is incomplete for determining cis-trans isomerism. For the complete alkene CH3CH=CHCH3 (2-butene), cis-trans isomers are possible: cis-2-butene and trans-2-butene. Without a double bond or additional substituents, cis-trans isomerism is not applicable.

Step-by-step explanation:

The molecule with the condensed structural formula CH3CH2CH as provided in the question seems incomplete for determining cis-trans isomerism. However, based on a similar example, if we consider the complete alkene CH3CH=CHCH3 (2-butene), this molecule does allow for cis-trans isomers as the double bond creates a situation where the configuration of substituents can differ on either side of the double bond.

The cis isomer of 2-butene has both methyl groups on the same side of the double bond, which would be named cis-2-butene. The trans isomer has the methyl groups on opposite sides of the double bond, named trans-2-butene. If the question intended to refer to 2-butene, then the answers would be:

name of cis isomer or molecule: cis-2-butene

name of trans isomer or none: trans-2-butene

If the molecule provided is indeed CH3CH2CH, without additional information such as a double bond or another substituent, cis-trans isomerism is not possible and the compound cannot be properly named as given.

Answer 2

CH₃CH₂CH - Prop-1-yne - does not exhibit Cis-Trans isomerism.

Step-by-step explanation:

Cis-Trans isomerism occurs mainly in organic compounds who have two different substituted compounds either of both sides (Cis-) or different sides (Trans-) of a doubly-bonded C=C compound.

That is, Cis-trans isomerism occurs in substances with structure

R₁-C=C-R₂

where R₁ and R₂ are different substituted hydrocarbons

Aklynes are triply bonded carbon compounds, who though are restricted from rotating around the C-C triple bonded, however cannot contain more than one substituted hydrocarbon as a result of the same C-C triple bond (C≡C)

Hence, prop-1-yne, CH₃-CH≡CH cannot exhibit Cis-Trans isomerism.