[Jdizzle]

The problem states to synthesize butanal with only propene as your source of carbon. You are allowed to use two separate reactions on the propene to later combine and make the butanal. I am specifically having problems with understanding how combining two 3 carbon structures can somehow create a 4 carbon structure. Does anybody have any advice?

[sjb]

The problem states to synthesize butanal with only propene as your source of carbon. You are allowed to use two separate reactions on the propene to later combine and make the butanal. I am specifically having problems with understanding how combining two 3 carbon structures can somehow create a 4 carbon structure. Does anybody have any advice?

What reactions of alkenes do you know?

[Jdizzle]

Like addition, elimination and substitution but nothing to change the number of carbons. I figured since I have to connect them that I will change one propene to an alkyne and the other propene to propyl chloride and then connect them forming hex-2-yne. Which I have no problem doing, I just don't know how to get butanal from it. Ozonolysis won't do it and its the only way I know how to split an alkyne up into two molecules.

[kriggy]

Try to draw enol form of butanal, it might give you an idea

[Jdizzle]

CH3-CH2-CH=CH-OH and I know tautomerism can turn it into butanal, but I don't understand how to get that enol from hex-2-yne. Water wouldn't do it right? or would it? Thanks for being so helpful guys. Most forums just ignore people trying to learn. I feel like I need to know a reaction to turn hex-2-yne into a terminal alkyne with 4 carbons. We never learned how to chop off carbons from a structure.

[Jdizzle]

Figured it out. I needed to change the hex-2-yne into a hex-2-ene before I did ozonolysis. Thanks! This was driving me insane.

[kriggy]

Well obviously I missread your description of that problem. 

Gj on figuring that out on your own  feels better that if we gave you direct answer right?