Sciencemadness Discussion Board

benzyl chloride syn

ariep641514 - 29-12-2015 at 04:39

any body can give advice, its possible to synthesis benzyl chloride by reacting benzyl alcohol + NaCl + sulfuric acid?

sulfuric acid helps benzyl alcohol to release -OH by dehydrating them, and remain sulfuric acid react with NaCl to formy anhydrous HCl, that correct or not?

i just try to get high yield benzyl chloride by reacting between benzyl alcohol with anhydrous HCl fumes generated in situ by salt and sulfuric acid will do the job, but minimized distilation process

any another reaction will involved? thx for explanation

fluorescence - 29-12-2015 at 10:39

So for your reaction I'd have to think about the mechanism first to answer you what would happen.
I just checked the database for your desired reactant and product and it gave me some possibilities depending on what chemicals you have acess to.

So from Benzyl Alcohol Benzyl Chloride has been prepared with:
(leaving out some exotic ones like Hydrides...)

- Tin(IV)Chloride
- Thionyl Chloride
- Zirconiumoxychloride + LiCl
- Oxalylchloride
- Tungsten Hexachloride
- Bismuth(III)Chloride (with some loss)
- Vanadiumoxychloride

You might also check the following paper:
An Efficient Synthesis of 2-(Halogenomethyl)penems

I just had a look into it they seem to use CaCl2 there but I'm not sure about the other reagents used since I didn't want to read the whole paper for it. If you need an information to any of the reagents mentioned above I can send you a link to the paper I just didn't want to copy all of them into here.

NitreRat - 29-12-2015 at 11:32

Quote: Originally posted by fluorescence  

So from Benzyl Alcohol Benzyl Chloride has been prepared with:
(leaving out some exotic ones like Hydrides...)

- Tin(IV)Chloride
- Thionyl Chloride
- Zirconiumoxychloride + LiCl
- Oxalylchloride
- Tungsten Hexachloride
- Bismuth(III)Chloride (with some loss)
- Vanadiumoxychloride

You might also check the following paper:
An Efficient Synthesis of 2-(Halogenomethyl)penems


...Or you know... just reacting it with hydrochloric acid.

blogfast25 - 29-12-2015 at 11:57

Quote: Originally posted by NitreRat  


...Or you know... just reacting it with hydrochloric acid.


Primary alcohols don't react very well with HCl. Unless you can distil off the reaction product, which here has a BP of 179 C.

blogfast25 - 29-12-2015 at 12:17

Quote: Originally posted by ariep641514  

sulfuric acid helps benzyl alcohol to release -OH by dehydrating them, and remain sulfuric acid react with NaCl to formy anhydrous HCl, that correct or not?



Benzyl chloride.gif - 3kB

But as I wrote above, that reaction doesn't proceed very well, unless you remove the reaction product continuously, or use a catalyst.

[Edited on 29-12-2015 by blogfast25]

NitreRat - 29-12-2015 at 12:21

Quote: Originally posted by blogfast25  

Primary alcohols don't react very well with HCl. Unless you can distil off the reaction product, which here has a BP of 179 C.


Yes, but benzyl alcohol is a bit of an exception. Just mixing concentrated hydrochloric acid and benzyl alcohol then separating and drying the organic layer, followed by fractional distillation will give to a decent yield of benzyl chloride.

blogfast25 - 29-12-2015 at 12:28

Quote: Originally posted by NitreRat  

Yes, but benzyl alcohol is a bit of an exception. Just mixing concentrated hydrochloric acid and benzyl alcohol then separating and drying the organic layer, followed by fractional distillation will give to a decent yield of benzyl chloride.


I didn't think the electron pushing effect of the phenyl group would reach that far.

Crowfjord - 29-12-2015 at 14:45

It does, Blogfast. It has to be concentrated hydrochloric acid, but it works pretty well. I have done it a couple of times, here is an example with a reference.

blogfast25 - 29-12-2015 at 15:59

Quote: Originally posted by Crowfjord  
It does, Blogfast. It has to be concentrated hydrochloric acid, but it works pretty well. I have done it a couple of times, here is an example with a reference.


In that case, in the spirit of OP's question, 40 % H2SO4 saturated with NaCl should probably work.

AvBaeyer - 29-12-2015 at 19:04

I have run the following reaction many times on much larger scale (20X) than described.

CHLORINATION OF BENZYL ALCOHOL WITH CONC. HCL [3]

2g benzyl alcohol and 6g concentrated hydrochloric acid were mixed and slowly heated. at 60°C the mixture separated into two layers. the yield of benzyl chloride was 70% of the theoretical. When the alcohol and a large excess of the acid were mixed, the reaction took place at the room temperature after a few minutes, and a theoretical yield of the chloride separated. Benzyl alcohol dissolves sparingly in hydrochloric acid of the specific gravity 1.12. when the solution is warmed, benzyl chloride is formed. Benzyl bromide and benzyl iodide were prepared in the same way from the corresponding acids.

[3] J F Norris, American Chemical Journal 38: 627-642 (1907)

The reaction does not work nearly so well with 31% hardware store acid. Benzyl chloride is formed but also dibenzyl ether is a significant by-product. Far less ether is formed with 37% acid and yields of benzyl chloride are >90% after distillation. This observation may need to be taken into consideration when using mixtures of sulfuric acid and NaCl.

AvB

zed - 29-12-2015 at 19:54

First time?

The vapors from Benzyl Chloride are very lachrymatory. Like Satan's Farts, more or less.

Best to use a fume hood, or some other high volume ventilation system. Otherwise, the tears streaming down your face, can make it hard to work.

The Benzyl Carbonium Ion is pretty stable.....meaning reactive. Other alcohols may not be so amenable to substitution. Likewise, Benzyl Chloride readily forms a Grignard reagent. Other Alkyl/Aryl Chlorides may be less compliant. Gotta use Bromides or Iodides, instead.

Apparently, Carbonium Ion, has become a dated expression. Gotta read up.

ariep641514 - 29-12-2015 at 19:54

wow, thx for quick reply, i already try simple measure 0,1 mol benzyl alcohol and NaCl , 0,2 mol sulfuric acid 96%. first i mixed benzyl alcohol and nacl, then slowly drop sulfuric acid, first it getting warmed, then then start bubling and whole mixture became intensely yellow orange colored with alot fume, which i believe its benzyl chloride are formed. but not brave to direct inhale that :), any advice for simple test benzyl chloride? now prepare for destilation, wonder for the yield :)

btw for reacting benzyl alcohol with hcl already test and its worked, i just want to increase yield by directly reacting it with anhydrous hcl, since if i use concentrated acid it use alot volume of hcl ( highest conc. only 36%) and more volume to distilate. Oh yeah fluorence thx for your idea using CaCl2 it will more efficient if that work, i will try later :)