[pdffree]

How do you get 2-pentanol  from  formaldehyde?
Anyone?

[macman104]

Do you know the grignard reaction?  Can you see the part of 2-pentanol that may have come from formaldehyde?

[pdffree]

Do you know the grignard reaction?  Can you see the part of 2-pentanol that may have come from formaldehyde?

Not only me but everyone in the class is having hard time!< Morever its an online class and he posts notes that doesn't help the class!.

[macman104]

I'm sorry, if you came here expecting the answer, you should have read the forum rules first.  That's not how it works.  We ask you questions, and help guide you to the correct answer, so you can learn the material and understand how to solve the problem in the future. 

If I just give you the answer, you would have gained little to no knowledge about the underlying mechanisms and things you should consider in solving the problem.  So if the structure were changed slightly, you wouldn't have the basic understanding in order to solve it, and you would be stuck again.

The teacher sucks, fine.  But you're in college, put in the effort that is expected of you, and do some studying.

So, I'll ask again, have you heard of the grignard reaction?
Do you have a textbook that you were required to buy for the class (online classes can still have a textbook).

[pdffree]

yea!
I have the textbook! looking at the book!
and unfortunately we had him in ORG 1, and thats why we are having hard time!

[macman104]

Ok, good.  Now look up the chapter on the alcohols, find the section that talks about grignard reaction.  What are the two pieces of a grignard reaction?

[pdffree]

Ok, good.  Now look up the chapter on the alcohols, find the section that talks about grignard reaction.  What are the two pieces of a grignard reaction?

I can see similar reactions in the book but in reverse direction!1. (RMGX, ether 2. H3O+

[macman104]

What reacts with the RMgX?
What is formed as the product?

[pdffree]

What reacts with the RMgX?
What is formed as the product?


i am looking at this link:
http://depts.washington.edu/chemcrs/bulkdisk/chem238A_win05/notes_14_06_10.pdf
and see that Grignard reagents react with formaldehyde to give primary alcohols.
but I want it the other way!

you can see it the attachment!

[macman104]

Oh, no that is an organic notation.  The open arrow like that means "make the left side from the right side", so you are looking at turning formaldehyde into a secondary alcohol?

So, what carbonyl do you use to make a secondary alcohol?
Can you make that type of carbonyl from a primary alcohol (look at oxidations of alcohols)?

[pdffree]

Oh, no that is an organic notation.  The open arrow like that means "make the left side from the right side", so you are looking at turning formaldehyde into a secondary alcohol?

So, what carbonyl do you use to make a secondary alcohol?
Can you make that type of carbonyl from a primary alcohol (look at oxidations of alcohols)?

do i have to use Cro3/H2so4 for the oxidation of alchol?

and at the end alcl3 to remove Ch3Ch2?

[macman104]

Well, CrO3 with H2SO4 will give you a carboxylic acid.

What is the type of carbonyl that is used to make a secondary alcohol from?  There is a milder oxidation that will convert a primary alcohol into this type of carbonyl.

Also, if you read through that pdf in there, it talks about how to break apart a alcohol into pieces.  You are going to have to break yours twice.

First time, you'll get one type of carbonyl and a grignard reagent.
Second time, you'll break your carbonyl into two pieces and then you'll get your formaldehyde and another grignard reagent.

I'm not sure what you meant about the alcl3 to remove CH3CH2.

EDIT:  By the way, I'm glad to see you decided to take a proactive approach about this instead of saying you can't do it because your teacher sucks.

[pdffree]

i did this . What do you do next? see the image attached.

[macman104]

Answer this question before we continue:

What type of carbonyl compound when reacted with a grignard reagent forms a secondary alcohol?

[pdffree]

Answer this question before we continue:

What type of carbonyl compound when reacted with a grignard reagent forms a secondary alcohol?

aldehydes