[NewtoAtoms]

Which one of the following reacts with ethylmagnesium bromide to form a chiral alcohol.

a.  acetone
b.  2-butanone
c.  acetaldehyde (ethanal)
d.  propanal
e.  cyclopentanone

I have done all the leg work, which I will post below, I just would like if someone could verify and tell me if my calculations and reasoning is correct.

a.  acetone + CH3CH2MgBr = 2 methyl-2-butanol
b.  2-butanone + CH3CH2MgBr = 3 methyl-3-pentanol
c.  acetaldehyde + CH3CH2MgBr = 2 butanol
d.  propanal + CH3CH2MgBr = 3-pentanol
e.  cyclopentanone + CH3CH2MgBr = 1-ethyl cyclopentanol

If I refer to my notes I can see that a chiral alcohol has a C which is attached to 4 different substituents.  Therefore in the above questions and answers, ONLY c. 2 butanol is attached to 4 different substituents (CH3, OH, H, CH2CH3)

However I am torn between c and e.

Can anyone help me with my reasoning and tell me if I am correct to assume that C is correct?

Thank you so much for your time and help

New to Atoms

[alexjaco]

To make a chiral alcohol from a Grignard, you need an asymmetric ketone of aldehyde, acetone is ruled out and so is cyclopentanone.  The other three, all have different "R" groups on either side of the carbonyl which would create a chiral alcohol, UNLESS either side is the same chain as the Grignard, which rules out 2-butanone and acetaldehye.

[NewtoAtoms]

Okay I understand why it's not acetone, 2-butanone, cyclopentanone, however I don't understand how to choose between acetaldehyde or propanal.  I understand that you are learning toward propanal, however due to my calculations I don't understand.

                                           O                               OH
                                           ll                                l
c.  acetaldehyde (ethanal)  CH3CH + CH3CH2MgBr = CH3CH
                                                                            l
                                                                            CH2CH3

This to me is a chiral molecule because it has a central C with 4 different R' attached.

                                                 O                                      OH
                                                 ll                                       l
d.  propanal                      CH3CH2CH  +  CH3CH2MgBr = CH3CH2CH
                                                                                         l
                                                                                         CH2CH3

This to me is achiral molecule because it has a central C attached to 2 of the same R'.

Would you be so kind as to why you believe it to be propanal. 
Because perhaps I am not understanding this topic 100%

Thank you for your time.

New to Atoms

[alexjaco]

I am sorry, you are right, its not propanal, its acetaldehyde that would give the chiral alcohol.