[HP]

Hi everyone...
I would like to know if possible to conjugate hydroxy compounds to acrylic acid and the reaction conditions and catalyzators used this. I know the OH hydrogen is not very mobile but may be its possible do this reaction...
Waiting your suggestions friends

[movies]

I think that in general the reverse reaction is too fast to allow the Michael product to be isolated.

[HP]

I red this i am searching for is called "oxa-Michael addition" of alcohols to unsaturated compounds. I red its catalized by acids and some other.. Do you think this reaction will work with some alcohols and acrylic acid in presense of conc. H2SO4 and if could what is the mechanizm this addition?

[movies]

With a carboxylic acid you're probably more likely to just get a Fisher esterification reaction.  After that you might get some of the beta-alkoxy ester from a subsequent Michael addition.

[HP]

Thanks for reply.
 You are right for the esterification reaction with free carboxylic group of acrylic acid. If i first protect it as ester with 1mol equiv alcohol then probably the second mole alcohol will react by Michael addition with the unsaturated acrylic ester..Also i am thinking the possible addition reaction of H2SO4 to unsaturated bond of acrylic acid forming its sulfate - do you think its possible as intermediate if first sulfuric acid with acrylic one and how it will influence its reaction with the alcohol? Sorry for the many questions but its interesting for me  

[movies]

The sulfate anion is a very poor nucleophile, so I don't think that trying to use that as Michael nucleophile would work.

Esterification of the acid might help, but then you have to worry about trans-esterification in the next reaction.

[HP]

Transesterification is possible but if i use the same alcohol in excess first for esterification the carboxylic group and eventually next step for oxa-Michael addition to acrylic ester if that work- thats what i am thinking about...I know alcohols react with conc. H2SO4 first forming corresponding sulfate ester which is stable if not heating to dehydrating alkene product. May be this sulfate OH will be much reactive than alcoholic OH for  Michael type addition reaction with activated double bond of acrylic ester but then to form the desired product: R-O-CH2CH2COOR i imagine SO3 should be eliminated or something other happens I am not very familiar with these mechanisms just try my imagination
Greetings HP

[movies]

Yes, using the same alcohol would solve the trans-esterification problem.

As to making sulfate esters, I think that you need pretty strong dehydrating conditions to form things like dimethyl sulfate from sulfuric acid and methanol.

For a Michael addition you are probably better off with an alcohol than with a sulfate since the alcohol electrons on O aren't delocalized onto the rest of the molecule, and therefore are more nucleophilic.  Plus, RO- is a worse leaving group that a sulfate ion so that might slow down the reverse reaction too.

[HP]

Thank you for the comprehensive expl. The picture become clear to me i think. It's something similar the synthesis of diethyl ether from 2 mol ethanol and conc. H2SO4. But when we have activated double bond in the acrylic ester then next portion of alcohol in the present of acid immediately will form alkoxonium ion R-OH2+ which probably mediate alcoxy addition to activated 2bond. On the other hand i am little confused because remember the hydration reaction of ethylene with steam in presense of H3PO4 forming ethanol which further probably don't react with ethene molecule to form diethyl ether and i dont know why so  

[movies]

Yeah, I had thought about the ether side reaction too.  I'm not exactly sure why that doesn't happen with phosphoric acid, but I do know that the reaction with ethanol and sulfuric acid is actually quite inefficient as is only used because all the ingredients are so cheap.

[HP]

Aham i think it doesnt happen becase kinetic control: the reaction mixture pass true heterogenic supported catalyst eg SiO2/H3PO4 for a very short time in the reactor and the formed ethanol flow out before it could convert to diethyl ether by bimolecule dehydration reaction with the acid(2moles alcohol loss 1mol water) or the possible side oxa-Michael reaction with 1 mol ethene by other mechanism. The reverse reactions of hydration ethene and its dehydration are in equilibrium. Heres some links i found:
http://www.chemguide.co.uk/physical/equilibria/ethanol.html
http://www.chemguide.co.uk/physical/catalysis/hydrate.html
http://www.chemguide.co.uk/mechanisms/elim/dhethanol.html#top
Interesting discussion i continue thinking  

[movies]

That is interesting.  I don't know very much about the various processes used for mass production of commodity chemicals.  I wish I new more about them though.  The amount of engineering that goes into making those processes so efficient and cost effective is really remarkable.

[HP]

Yes, efficiency's essence of chemistry enginering. Theres some new facts i lerned this current topic. Theres many artcles for addition of alcohols to acrylonitrile and the process is called cyanoethylation. It's catalyzed most often by bases.
R-OH + H2C=CH-CN --> R-O-CH2CH2-CN which nitrile could easily hydrolyzed to corresponding eter-acid. This i am asking for is if the nitrile group is much better activating the double bond group than the carboxylic or ester-caboxylic one and how to explai it with induction- mesomeric effects or polarity bonds?
I know that cyanacrylates are extreemly reactive compounds which readily react and with water by polimerizing in the well known super glue. In its molecule theres two groups: cyano and ester-carboxylic one and they both interact with the double bond to "super activate" it. Theres superposition of 2 +I effects i think.
2HC=C(CN)COOR
H2O + 2HC=C(CN)COOR--> HO-CH2CH(CN)COOR + 2HC=C(CN)COOR--> quick polymerization by ion mechanism but i still dont look the carboion(cation or anion) ? Dont try between your fingers or eyelids!!
If i am not alredy boring  discussion may to continue thanks.

[movies]

Well, after the first Michael addition of OH- into the acrylate you have a very acidic proton (pKa ~ 12) between the two withdrawing groups.  The anion is then capable of performing a second Michael addition into another acrylate and so on.

[HP]

You are absolutely right for the acidic proton after addition H2O to cyanacrylate!Can you please figure the anion and how exatly it's forming and the next developing the polymerization process as you viw it?
Thanks!