Cl2, S2Cl2, SOCl2 & acid chlorides

[Mountain_Girl]

Comments & criticisms please:
SWIM wasted her supply of SOCl2 in an incident that could have been prevented with a suck back trap. She wasn't that perturbed (she's become blase' about mishaps & near fatal gassings) until the chem supply house informed her that SOCl2 is now considered too hazardous for sale. That was troubling news, but since her philosophy is to use supply houses only for innocuous and unsuspicious chemicals anyhow, she decided to investigate the possibility of OTC SOCl2.
What she has come up with is this theoretical approach:

1. Cl2 + 2S = S2Cl2, according to US3992509
2. (a) S2Cl2 + Cl2 = SCl2 i.e. generated in situ
    (b) 2H2SO4 + 3SCl2 + Cl2 = 2SOCL2 + 3SO2 + 4HCl
       (catalyst =  HgCl2), according to US1861900

Progress so far:

S2Cl2 was generated by passing dry Cl2 thru molten S (about 200 g initial charge) and condensing the exit vapor.
Don't have time to supply complete practical info (assuming anyone wants them I can produce later), but important notes I can think of now, are:
a. Temp must be fairly high (200 to 300 °C)
b. S must always be in excess. Fortunately it's cheap & OTC.
c. Cl2 generated by dripping 15% bleach into conc. HCl. Can't remember quantities right now. This method superior to HCl + KMnO4.
d. Cl2 bubbled thru S. Temps high enough so that plugging of gas dispersion tube not a problem.
e. Small amount (< 1/2 g) of 'Ferric chloride' used as a catalyst. 'Ferric chloride' made by leaving 3 or 4 nails in a few ml conc. HCl overnight, filtering ppte and drying in oven.
f. No absorbtion device for unreacted Cl2 was used. Fortunately it seemed that just about all the CL2 reacted.(By now SWIM swears she's immune to the stuff anyhow).
g. About 80 ml (~ 120 g) of ye old amber liquid with an unpleasant odor was produced. Not sure about purity. However very little S floating around. Also contamination with SCl2 will not be a problem since the idea is to generate it in rctn 2(a) anyway. Therefore it has not been distilled and currently sits in a fridge. Do hope it doesn't react to polysulfides (see

Post 208279

(Antoncho: "Re: An easy OTC 2,5-diMeO-phenylmercaptan", Novel Discourse)).

Overall procedure is similar to

Post 208025

(Antoncho: "Preparation of S2Cl2", Novel Discourse) &

Post 208077

(catastrophe: "Re: Preparation of S2Cl2", Novel Discourse) just at higher temps.

Questions for the bees:
1. How to clean a pile of sulfur fouled glassware (SWIM got no CS2) ?
2. Ultimately SOCL2 could be used for 3,4,5-TMB-COOH + SOCL2 = 3,4,5-TMB-COCl. Any ideas on using S2Cl2 itself for this reaction ? In

Post 229993

(foxy2: "Acetyl Chloride/Acid chloride production!", Chemistry Discourse) some patents were described for methyl substituted aromatic acid chlorides but nothing on methoxy versions.

Oh one last point of clarity:
SOCL2 = Thionyl Chloride
SO2CL2 = Sulfuryl Chloride
S2Cl2 = Disulfur dichloride, often called 'Sulfur monchloride'
SCl2= Sulfur dichloride
,just in case there is still confusion.

[foxy2]

This might work for cleaning.
Foxy

Reaction of sulphur with bases
Sulphur reacts with hot aqueous potassium hydroxide, KOH, to form sulphide and thiosulphate species.

S8(s) + 6KOH(aq)  2K2S3 + K2S2O3 + 3H2O(l)

http://www.webelements.com/webelements/elements/text/S/chem.html

I hate my government, does this mean I'm a terrorist??

[hest]

Mountai... you are a tuff girl, thats real synthesis *lol*

For the convertion of TMBA to TMBC SOCl2 works greath with and withouth a solvent (you can use almost annye solvnet (not an alkohol ore wather Wath is the next step from the acidchloride, the aldehyde ??

[Mountain_Girl]

Yes Hest, the aldehyde is the next step via a room temp. Pd/C Rosenmund method I found.
I think you misunderstood my question regarding the use of S2Cl2 for TMBA to TMBC. I meant using S2Cl2 as the chlorinating agent, i.e. no SOCL2. SWIM doesn't want to proceed to the next step of making SOCl2 from S2Cl2 if it's not necessary (although she might at a later stage just to show that it can be done OTC).

BTW thanks for the reply Foxy - SWIM will give the KOH a try

[hest]

Rosenmund is sometimes a trickey one. Alternative is to reduce the acid to the alkohol and then oxidise it to the aldehyde (with MnO2, works greath).
 But give it a try, sounds interesting.
(Personal i start with vaniline instead, I find that routhe the easyest way)

[Ritter]

Mountain Girl,

There is a better halogenating agent out there which can be easily made from Cl2 gas which you apparently have a certain fondness for .  If you can get your hands on some red phosphorous, phosphorous trichloride can be made by bubbling Cl2 into a carbon tetrachloride solution of the P.  Bromine is a good substitute here and results in formation of phosphorous tribromide.  Either of these halogenating agents are FAR superior to SOCl2 in my book.  If interested, let me know and I'll type up the synth for you.

However, since you mentioned you were planning on running a Rosenmund on the acyl chloride, that means you have access to Pd and H2.  A much nicer, cleaner approach to the benzaldehyde would be to form the ethyl or methyl ester of the acid, reduce to the benzyl alcohol with catalytic hydrogenation, make the benzyl chloride with plain old 37% HCl, then react with hexamine and hydrolyze to get your benzaldehyde.  This is a MUCH safer procedure than any of those which involve messing with halogenating agents (unless you are working with one hell of a good fume hood)

[Mountain_Girl]

Hest,
For historical reasons I won't go into, SWIM has a fair amount of TMBA lying around so she wants to give this method a try. However she will keep your alternative (alc. + MnO2) in mind for the future.
I've noticed that Rosenmund is not popular with the bees (TFSE did not produce many hits) - is that because of low selectivity, long reactions times or what exactly ?

[Mountain_Girl]

Ritter,
Preparing PCl3 or PBr3 did indeed cross her mind but believe it or not, Pd is easier for her to get than red P (excluding the match book striker option which is not really an option). Thanks for the offer of the synth, if I get hold of any P one day I'll bug you for it.

SWIM had considered the similar route:
TMBA to ester to alc. to chloride to nitrile to amine, but decided it would be much easier overall to use the Rosenmund route if she could actually get it to work. If it doesn't, she may try your route after all.

SWIM used to think she was not a particularly reckless bee but you guys are starting to make her think otherwise. That's probably a good thing...

[hest]

Mountain_Girl, the Rosenmund reduction is not so pop. becourse it a bit trickey, it not allways works, sometimes nothink happends and sometimes you end up wit the alkohol.
But it is deff. not imposible to work with, might just need some tuning.

[Greensnake]

> A much nicer, cleaner
> approach to the benzaldehyde would be to form the ethyl or methyl ester of the
> acid, reduce to the benzyl alcohol with catalytic hydrogenation,

Won't work with catalytic hydrogenation, esters are not all that great substrates
for cat. hydrog., while bezylic alchohols on the contrary are, so you either will
get unchanged ester back or will happily hydrogenate it further to the
3,4,5-trimetoxytoluene. Swim even strogly suspects, that in this particular
case benzene ring will hydrogenate easier than ester, yielding something like
3,4,5-trimetoxycyclohexane carboxylic acid whatever ester.

Greensnake

[Ritter]

Greensnake:
Just looked it up and it looks like you are certainly correct ,  but there are a shitload of exotic hydride agents which convert the ester directly to the benzaldehyde in high yield such as Sodium bis(methoxyethoxy) aluminum hydride,  LiAlH2(NEt₂)2.  Let me know if you want refs.

[Mountain_Girl]

Oops, we're going a bit off the original topic here, although it is interesting and still useful.
SWIM has kind of committed herself to the Rosenmund (due either to a pioneering spirit, fierce independance, or brain malfunction thru repeated exposure to toxigens).
Also doesn't want to waste any of her precious supply of LAH on ester reduction which it now seems may not work. She's saving it for the final nitro-styrene reduction.
Unfortunately exotic agents are exactly what she is not looking for (actually DEA agents as well).

[Antoncho]

Dear Mountain Girl!

First, let me inform you that this patent on making SOCl2 is absolutely cool and i've been looking for one like that for a long time. Thanks!

And - here are more useful tidbits of info.

SCl2 is a very unstable substance and should bee used directly after preparation, well actually it decomposes to S2Cl2/Cl2, so probably won't matter much in this case. It can bee stabilized w/PCl3 or some Pred.

I also have a coupla proc's on making SCl2 directly from sulfur an even making SBr2 (yikes!) - the latter is pretty dangerous. If anyone is interested, i'll post them.

Then - SOCl2 can bee easily (as much as this word applies here ) purified from residual SCl2 bu distillation over some sulfur, with wich SCl2 reacts, forming high-boiling S2Cl2.

Pray tell me, do you plan to perform this synth in one pot? I'm really looking forward to hear from you more!

Antoncho

[Mountain_Girl]

Ah Antoncho! I was hoping you or Catastrophe would show up since you've both got some practical knowledge of dabbling with these dark compounds!

Glad I could help with that SOCl2 patent. There are also these: US2431823 & US2362057 ,but I don't think they are quite as useful as the other one.
Also this reference: 'Handbook of Preparative Inorganic Chemistry', vol. 1, G. Brauer 2nd ed., p 382-383, which I haven't been able to get hold of.
Another patent worth checking is US3156529 for the purification of SOCl2.

The next step for SWIM is to get hold of some 100% H2SO4 or 98% at least. Then reflux it with the S2Cl2 that she's already made while bubbling thru Cl2 i.e. exactly as stated in the patent.
The cool thing is that by using S2Cl2 & Cl2 to generate the SCl2 in situ, the instability of the latter is not an issue. At present it's effectively 'stored' as S2Cl2.

Damn! - can't discuss further, my other life is intruding, gotta go, will be back at a later stage.

[Antoncho]

Ah Antoncho! I was hoping you or Catastrophe would show up since you've both got some practical knowledge of dabbling with these dark compounds!

Me, hardly at all  I wonder where Catastrophee is now ...

You see, SWIM nearly killed himself a coupla times trying to make smth. that could bee substituted for POCl3 in Vilsmeier formylation. So now he's really elated about finding such a simple one-pot way to make SOCl2.

One-pot it is. You just make SCl2 from S (no need for S2Cl2 in doing this) and then, just replace the vessel w/the one w/H2SO4 & HgCl2 and add SCl2. Amazingly simple!

That is in theory, of course. In practice there's however une petite probleme - you can do it only in a fume cupboard. Controlling the temp should bee no problem, BUT - don't use anything other than glass all the way - SCl2 dissolves fucken anything (like rubber or PVC). Actually, when working w/small quantities, probably, some reactor similar to a test-tube could bee needed for better absorption of chlorine - so there might bee no alternative for hand-stirring the mixtr w/a thermometer during the addition, at least in SWIM's ghetto case. This would also mean an icebath can't bee used for cooling - at least, open icebath. Ice-cooled oilbath, maybee...

Ok, i realize i'm beginning to sound like FMAN now, just wanted to share my thoughts - maybee it helps.

SWIM personally has a neat self-made, albeit small, fume cupboard, which will probably do for him.

Um... It also occured to me now that both SCl2 and H2SO4 could bee cooled like to -25 C in a freezer prior to use, in which case it's not so one-pot no more, but definitely less hazardous than otherwise. BTW, they say - "not higher than 30 C", any ideas what it might mean? In SWIM's fucking experience, such mixtures (like an unstable/prone to oxidation compd. w/conc. H2SO4) are subject to various chain rxns, very exotermic      - that is, if you hit 32 C, you may not only have some stuff evaporate, but it all may turn into an uncontrollable volcano, which will certainly make the place uninhabitable for a long time  Beware.


Antoncho

[Mountain_Girl]

At last I return.

Antoncho,
Firstly, congratulations on the Hydroquinone/NaMeSO4 work & all the other OTC projects you're looking into. Please keep it up. I'll try to give useful input where I can.

Regarding the SOCl2 prep:

The reason SWIM made S2Cl2 rather than SCl2 is
i) seemed fairly straightforward (it is)
ii) thinking of using it as SOCl2 substitute to make the acid chloride 3,4,5-TMBC (or others). I'll probably have to start a new thread on this one.
iii) she knew the S2Cl2 would keep until she could get hold of conc. H2SO4, unlike SCl2

Anyhow your thoughts in your last post were useful 'cos it got SWIM thinking on the more practical issues of maing SOCl2.
I reckon that pre-chilling the reactant (S2Cl2 in SWIM's case) is indeed the way to go. The H2SO4 would also chilled & saturated with Cl2 before adding the S2Cl2 slowly.
I'm not sure why < 30°C is recommended but you're probably right about its exothermia. I think it will be a good idea to test with a small amount in a test tube first. The patent speaks of refluxing after mixing until a homogenous mixture results. This suggests to me that the reaction proceeds readily below 30°C in the presence of a catalyst and that the final reflux is just to react the last amounts. Above this temp. perhaps there is excessive byproduct formation or maybe a tendency to form SO2Cl2 instead ?
When SWIM gets her H2SO4 she'll definitely let you know what happened.

[Mountain_Girl]

I feel it is my duty to report on successes as well as failures.
[ ]
Therefore, as far as the synth. of SOCl2 from S2Cl2 is concerned (via Cl2/H2SO4/HgCl2), I must sadly state that SWIM now has a stinking-yellow-sulfurized sculpture of glassware and zero grams of SOCl2.
The process was implemented pretty much as suggested by the patent. One difference is that '95 - 97 %' H2SO4 was used instead of 100%. According to the patent this is okay because the water would decompose some of the product and yields would simply be less. Maybe it's not okay.
Also, there was no reaction between S2Cl2 & the H2SO4 when they were added together initially. The mix simply separated into two layers.
Finally, after about an hour of refluxing with Cl2 addition, and much SO2/HCl generation, SWIM tried to distill the product. Some SCl2 came over at roundabouts 50°C and then nothing else, even after heating to about 80°C.
Perhaps SWIM refluxed for too long and any SOCl2 that was formed, decomposed ?
Another point of interest is that according to my calcs, the patent uses a little less than the stoichiometric amount of H2SO4.

Anyhow, even if SWIM did find out what went wrong, she couldn't be fucked doing this heavy duty type synth again. The hazards and clean up afterwards might be worth precursor synthesis but probably not a reagent, IMO.