Question

Problem #1. For a substance to be chiral, it must be non-superim means that the substance has an enantiomer. In most cases, chir stereocenters (a tetrahedral atom bonded posable on its mirror image. This al substances have one or more chiral substance that does NOT have any stereocenters a) Label each substance as CHIRAL or ACHIRAL have any sereccmtentit i to four different groups). However, it is possible to have a have CH3 H3C CH3 CH3 C-C-C H3C H3C H3C Ph b) Draw the enantiomer of each chiral substance from part a). c) Draw an ACHIRAL substance that is an isomer of ,3-pentadiene.

Answer 1

Since the vary basic knowledge about chiral compound and chirality is provided . However the compunds given are allenes and quarternary salts .

Allenes are of two kinds - planar and non-planar . Since the consitutents attached to every third carbon are perpendicular , odd number C allenes are non-planar and consitutuents attached to every fourth carbon are in same plane , even number C allenes are planar . However for allenes the basic criteria of chirality is that the two groups attached to the same C must be different , because the C-Chain to which all groups are attached is called chiral axis .

Quarternary salts are Nitrogen containing compounds have four groups attached to it with a positive charge of N atom due to donation of lone pair . However for quarternary salts also the basic criteria is that all four groups attached must be different .

Now , lets answer the questions -

(a) Since , since the first allene do not have two groups identical attached to same C it is CHIRAL.

The second allene has two methyl groups attached to same C , it is ACHIRAL .

The third allene has no two similar groups attached to same C , it is CHIRAL .

The quarternary salt has all group attached are different , thus it is CHIRAL .

(b) Enantiomers are the non-superimposable mirror images of a chiral compound .The two mirror images together form a pair of enantiomers . Since ,in part (a) (1) , (3) and (4) are found to be chiral thus we will draw their enantiomer.  

(c) 2,3-pentadiene is an allene , thus for it to be Achiral , the two groups attached to each terminating Cs must be similar .

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