Sciencemadness Discussion Board - diiodomethane

diiodomethane

Jor - 29-7-2010 at 13:05

I am interested in making maybe 3-4 mL of diiodomethane, just because I would like to have a liquid wich had such a high density (yes I know bromine also had this density, and bromoform).

I have quite a lot of iodoform (100g , reagent), and I never use this, so if I could start from this it would be great. According to Vogel, this requires me to use arsenic compounds, wich is no option on a preparative scale, especially, since I don't have As(III)-compounds. Do you guys know of another suitable reducing agent. I have access to quite some reducing agent, including hydrazine, hypophosphite, hydroxylammonium chloride, dithionite, tin(II) chloride, etc.

Otherwise I will go via Finkelstein reaction. I have KI, but this is supposed to work only slowly, so I will prepare some NaI , by reaction of iodine with a small excess of hydrazine in the cold (to prevent disproportionation of hydrazine to ammonia and N2, followed by formation of NI3.NH3), and neutralise this with sodium bicarbonate, and evaporate. Then dissolve this in acetone, add dichloromethane (NaI excess, 1,1x ?), stopper the erlenmeyer and leave this solution in the dark for a week, followed by filtering, boiling away the acetone, and finally filtering the excess NaI from the methylene iodide (I guess this is insoluble in CH2I2), and store this over some Ag-powder. Would this work to obtain relatively pure (95+%) methylene iodide? Also to what does methylene iodide decompose when exposed to light. What is formed apart from iodine?

Nicodem - 29-7-2010 at 14:02

Hypophosphite might do, but it is all about trying it out as I was unable to find anything in the litrature.

According to patent JP54066606 in situ formed hydrogen iodide reduces CHI3 to CH2I2: "CH2I2 was prepd. by redn. of CHI3 with HI generated in the presence of CHI3. Thus, 5.2 g red P was added to a mixt. of CHI3 100, I 15, Fe 1, and H2O 40 g and the whole kept 3.5 h at 115-20 to give 50 g CH2I2." (from patent's CA 91:174809)

According to Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya (1957) 1122-1123, CHI3 can be reduced by NaBH4: "To 16.6 g. CBr4 in 50 ml. MeOH was added in 25 min. 2 g. NaBH4 in 15 ml. H2O with 2 ml. 2N NaOH with cooling at 50 (gaseous boron hydrides escape during the reaction) and after 1 hr. the mixt. after washing with aq. NaOH gave 74% CHBr3. Similarly, 39.4 g. CHI3 and 3.8 g. NaBH4 in aq. NaOH gave 85% CH2I2." (from CA 52:34646)

Treating trioxane with AlI3 gives CH2I2 (Zhurnal Russkago Fiziko-Khimicheskago Obshchestva, 46 (1914) 705-708.)

It is interesting to note that CH2I2 can be obtained from CH2Cl2 by either the SN2 substitution (Finkelstein reaction), or by the SN1 substitution by using AlI3 on CH2Cl2 in CS2 (according to CA 107:197464 and the following patents; see also this post). According to patent CS208568 cyclohexane can be used as solvent to give CH2I2 in excellent yields: "Treating iodine with granulated Al and then treating the resulting AlI3 with CH2Cl2 gave 89-95% CH2I2, based on iodine. The novel feature was cycloparaffinic medium, such as cyclohexane or cyclooctane." (from the patent's CA 101:54542) Given that you are willing to start with I2, then why not using this method? Petroleum ether or some of its OTC variants might work as well if you have no cyclohexane. Furthermore according to the related patent CS144027 it can even be done without any additional solvents: "CH2I2 was prepd. in 1 step from CH2Cl2, Al, and iodine. Thus, a mixt. of 100 kg dry CH2I2 and 100 kg iodine was treated portionwise at 110-20 with 7.5 kg powd. Al, cooled to 30, 35 kg CH2Cl2 added at 40, AlCl3 filtered off, and the CH2I2 steam-distd. to give 75-80% pure product." (from the patent's CA 78:3665)

Another interesting thing I found while checking the literature is that pyrolysis of CHI3 at 320°C gives mostly CH3I and I2, together with a few % CH2I2, HI and CH4 (see Russian Journal of General Chemistry, 75 (2005) 1411-1420). Just as a curiosity.

chemoleo - 29-7-2010 at 14:04

I think you'll need way more than a week for the reaction - the NaCl still keeps precipitating after 6 months at room temp (indicating the reaction is not complete), so don't hold your breath (Ok the excess of NaI used wasn't particularly high)! Chloroform is even slower/useless.

(PS I'm referring to the reaction of NaI with DCM in acetone)

[Edited on 29-7-2010 by chemoleo]

Lambda-Eyde - 29-7-2010 at 14:14

Quote: Originally posted by chemoleo

I think you'll need way more than a week for the reaction - the NaCl still keeps precipitating after 6 months at room temp (indicating the reaction is not complete), so don't hold your breath (Ok the excess of NaI used wasn't particularly high)! Chloroform is even slower/useless.

(PS I'm referring to the reaction of NaI with DCM in acetone)

[Edited on 29-7-2010 by chemoleo]

Wow

Isn't there any way to speed up this?
Heating would be pointless, right? (Since the reaction is driven forward by the differences in solubility, if I'm not mistaken?)

chemoleo - 29-7-2010 at 14:29

Well you could microwave it in the dark

Yes it is driven forward by that but bear in mind that acetone does actually dissolve some NaCl, as evidenced by a lag in the appearance of NaCl precipitation (it actually appears as tiny crystals) - in fact I thought the reaction hadn't worked at first because the solution just went more yellow, but no precipitation!
I can take a pic of the reaction when I think of it (now on month 9) and post it.

Lambda-Eyde - 29-7-2010 at 14:33

Have you analyzed the mixture with GC-MS/LC-MS or anything like that during the course of reaction? It would be interesting to see how far the reaction has gone after one day, one week, one month, half a year and so on...

Edit: I guess even TLC would suffice to some extent.

[Edited on 29-7-2010 by Lambda-Eyde]

Sedit - 29-7-2010 at 16:01

Java provided me with this recently and I think it could possibly come in handy for you. It suggest that finely divided iron on an SiO2(IIRC)Support will dehalogenate chloromethanes all the way down to Dichloromethane. Given that Iodine is a better leaving group I would have to say you may get different results using iodoform but its still worth the read.

Reductive Dehalogenation of Chlorinated Methanes by Iron Metal
Leah J. Matheson, Paul G. Tratnyek
Environ. Sci. Technol.,
1994, 28 (12), pp 2045–2053
DOI: 10.1021/es00061a012

Attachment: Reductive Dehalogenation of Chlorinated Methanes by Iron Metal.pdf (1.1MB)
This file has been downloaded 1726 times

Jor - 29-7-2010 at 16:21

Quote: Originally posted by Nicodem

Hypophosphite might do, but it is all about trying it out as I was unable to find anything in the litrature.

According to patent JP54066606 in situ formed hydrogen iodide reduces CHI3 to CH2I2: "CH2I2 was prepd. by redn. of CHI3 with HI generated in the presence of CHI3. Thus, 5.2 g red P was added to a mixt. of CHI3 100, I 15, Fe 1, and H2O 40 g and the whole kept 3.5 h at 115-20 to give 50 g CH2I2." (from patent's CA 91:174809)

According to Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya (1957) 1122-1123, CHI3 can be reduced by NaBH4: "To 16.6 g. CBr4 in 50 ml. MeOH was added in 25 min. 2 g. NaBH4 in 15 ml. H2O with 2 ml. 2N NaOH with cooling at 50 (gaseous boron hydrides escape during the reaction) and after 1 hr. the mixt. after washing with aq. NaOH gave 74% CHBr3. Similarly, 39.4 g. CHI3 and 3.8 g. NaBH4 in aq. NaOH gave 85% CH2I2." (from CA 52:34646)

Treating trioxane with AlI3 gives CH2I2 (Zhurnal Russkago Fiziko-Khimicheskago Obshchestva, 46 (1914) 705-708.)

It is interesting to note that CH2I2 can be obtained from CH2Cl2 by either the SN2 substitution (Finkelstein reaction), or by the SN1 substitution by using AlI3 on CH2Cl2 in CS2 (according to CA 107:197464 and the following patents; see also this post). According to patent CS208568 cyclohexane can be used as solvent to give CH2I2 in excellent yields: "Treating iodine with granulated Al and then treating the resulting AlI3 with CH2Cl2 gave 89-95% CH2I2, based on iodine. The novel feature was cycloparaffinic medium, such as cyclohexane or cyclooctane." (from the patent's CA 101:54542) Given that you are willing to start with I2, then why not using this method? Petroleum ether or some of its OTC variants might work as well if you have no cyclohexane. Furthermore according to the related patent CS144027 it can even be done without any additional solvents: "CH2I2 was prepd. in 1 step from CH2Cl2, Al, and iodine. Thus, a mixt. of 100 kg dry CH2I2 and 100 kg iodine was treated portionwise at 110-20 with 7.5 kg powd. Al, cooled to 30, 35 kg CH2Cl2 added at 40, AlCl3 filtered off, and the CH2I2 steam-distd. to give 75-80% pure product." (from the patent's CA 78:3665)

Another interesting thing I found while checking the literature is that pyrolysis of CHI3 at 320°C gives mostly CH3I and I2, together with a few % CH2I2, HI and CH4 (see Russian Journal of General Chemistry, 75 (2005) 1411-1420). Just as a curiosity.

Thank you Nicodem for doing some searching!
Unfortunately I don't have sodium borohydride. I really need to buy this reagent, as I have come across many situations where using this reagent was a good option. It is quite expensive per gram, but considering the molar mass (and the fact that 1 mole contains 4 mols hydride), it is not expensive at all.

The method using red P sounds interesting, I have plenty of that. But I always prefer a method not involving red P. Maybe I can use hydrazine instead of red P to generate HI.
What is the function of the Fe? Reaction with I2 to form FeI3, wich acts as the halogen carrier (lewis acid) ? What are the amounts you state? 1g Fe, 100g iodoform, 40g H2O and 15g I2? And how am I supposed to keep this mixture at 115-120C, when the water will boil at 100C?

I am also quite interested in the reaction you mentioned, involving aluminium iodide. I can obtain a mixture of alkanes from the hardware store. But this also contains high boiling compounds, so I would first have to distill to obtain the fraction below 80-100C. And distillation is a problem at the moment, as my distillation apparatus hardly fits in my hood (I bought a way too large setup, NS29, and don't have the money and time to replace it with something more convenient (NS19). But because I don't have alternative solvents it seems that I'd liek to avoid this method if possible.
I figure I will have to distill anyway in the method with red P.

I would prefer Finkelstein, but I don't want to wait 6 months, so that's no option either.

Lambda-Eyde - 29-7-2010 at 17:02

Quote: Originally posted by Jor

And distillation is a problem at the moment, as my distillation apparatus hardly fits in my hood (I bought a way too large setup, NS29, and don't have the money and time to replace it with something more convenient (NS19). But because I don't have alternative solvents it seems that I'd liek to avoid this method if possible.

Your distillation setup isn't too large - your hood is too small!

But seriously, how big is your hood? A NS29 setup isn't that large, unless you're using a 600 mm condenser and a train of wash bottles. The hood I'm building is 120 cm wide, and that's an absolute minimum IMO. Of course it depends on your fan and how much space you have available.

Anyways, I wouldn't worry about distilling naphta/white spirit without a hood - it's not deadly toxic, and not much (if any) escapes through the vacuum port. Just make sure the receiver is quite cold.

Also, check your U2U - I sent you a message regarding NaBH<sub>4</sub>.

Jor - 30-7-2010 at 02:24

My hood is quite small, I think 80cm wide, but I didn't have enough room to build a larger one.
http://www.youtube.com/watch?v=NM5CjTwyNRo

But it works really well. I have done a few distillations in it, like bromine and near azeotropic HBr, but it's quite a hassle. And it sucks very well, I can't remember any time I smelled anything while I was using it correctly.

The problem is my vaccuum adapter broke last time, so I would have quite large opening in the setup, wich would potentially release lots of solvent vapours. Good I think of that now, I should order a new one.

benzylchloride1 - 30-7-2010 at 10:10

I have also been interested in diiodomethane because of its use in the Simmons cyclopropanation of alkenes. I have a procedure for the preparation of this compound from dichloromethane using the Finkelstein Reaction. The synthesis is completely OTC, since the solvent is acetone. The only apparatus needed is a glass beer or soda bottle to serve as a pressure vessel.

Procedure:

Methylene chloride, 30 grams is mixed with sodium iodide, 120 grams and warm acetone, 100 mL. The mixture is heated in a soda water bottle for 10 hours. The bottle is then recorked and heated for another 10 hours. The mixture is allowed to stand over night, the acetone is decanted from the sodium chloride, which is then washed with acetone. The acetone is distilled and the residue is mixed with water. The crude product is extracted with ether, the ether extract is washed with a sodium bisulfite solution, dried and the ether distilled. The crude product is fractionated under reduced pressure, collecting at 150 C @ 300 mmHg, the yield is around 60%,

Here is the original reference: Resolution of dl-trans cyclopentane 1,3 -dicarboxylic acid. William Henry Perkin junior, Harold Archibald Scarborough. Chemical Society Transactions, volume 119, 1921, pages 1400 -1408. The procedure is at the end of the article.

[Edited on 30-7-2010 by benzylchloride1]

[Edited on 30-7-2010 by benzylchloride1]

[Edited on 30-7-2010 by benzylchloride1]

Hexagon - 31-7-2010 at 02:16

In the entry for DIM at the merck index you've got a reference for the synthesis of that same substance with iodoform and sodium acetate, dunno if it works but...

JohnWW - 31-7-2010 at 06:01

I am interested in diiodomethane, or methylene diodide, CH2I2, because it is a liquid at ordinary temperatures that has a density of 3.325 gm/cc (see http://en.wikipedia.org/wiki/Diiodomethane ), which is greater than that of silica, 2.65 gm/cc, and nearly all common silicate and carbonate minerals. In fact, in the 1970s I bought an ampoule of it, which I still have. I am thinking of using it for prospecting for Au and Pt particles in alluvial deposits in rivers, particularly on the West Coast and central Otago in New Zealand's South Island, when the opportunity arises for me to visit those areas.

The only other readily obtainable liquids (at ordinary temperatures) with such an high density (greater than 2.65) are Hg (13.6) and Ga (6.095) and the eutectic alloy Galinstan (68.5% Ga, 21.5% In, 10% Sn)(6.44), but unfortunately these liquid metals dissolve Au and Ag; and Clerici's solution, which is an aqueous solution of very soluble thallium(I) malonate and formate (density 4.15), or acetate according to some sources, but which is very poisonous and corrosive, as well as costly due to the rarity of thallium. A possible substitute for Clerici's solution could be an aqueous solution of Pb(II) acetate, which is also very soluble, and much more readily obtainable, but the solution may not have quite an high enough density; see http://en.wikipedia.org/wiki/Lead(II)_acetate .

For a mention of the use of both CH2I2 and Clerici's solution in mineralogy, see http://books.google.co.nz/books?id=t-OQO3Wk-JsC&pg=PA62&...

[Edited on 31-7-10 by JohnWW]

Paddywhacker - 31-7-2010 at 12:25

Of the OP's topic, but acetylene tetrabromide, with a SG of 2.96, is readily made from acetylene and bromine, and is used in geology prospecting.

Eclectic - 31-7-2010 at 12:41

The lowest toxicity specific gravity liquid I was able to find for separating quartz from beryl was a solution of silicotungstic acid. the SG is about 3 at saturation in warm water.

JohnWW - 2-8-2010 at 06:47

Quote: Originally posted by JohnWW

I am interested in diiodomethane, or methylene diodide, CH2I2, because it is a liquid at ordinary temperatures that has a density of 3.325 gm/cc (see http://en.wikipedia.org/wiki/Diiodomethane ), which is greater than that of silica, 2.65 gm/cc, and nearly all common silicate and carbonate minerals. In fact, in the 1970s I bought an ampoule of it, which I still have. I am thinking of using it for prospecting for Au and Pt particles in alluvial deposits in rivers, particularly on the West Coast and central Otago in New Zealand's South Island, when the opportunity arises for me to visit those areas.

The only other readily obtainable liquids (at ordinary temperatures) with such an high density (greater than 2.65) are Hg (13.6) and Ga (6.095) and the eutectic alloy Galinstan (68.5% Ga, 21.5% In, 10% Sn)(6.44), but unfortunately these liquid metals dissolve Au and Ag; and Clerici's solution, which is an aqueous solution of very soluble thallium(I) malonate and formate (density 4.15), or acetate according to some sources, but which is very poisonous and corrosive, as well as costly due to the rarity of thallium. A possible substitute for Clerici's solution could be an aqueous solution of Pb(II) acetate, which is also very soluble, and much more readily obtainable, but the solution may not have quite an high enough density; see http://en.wikipedia.org/wiki/Lead(II)_acetate .

For a mention of the use of both CH2I2 and Clerici's solution in mineralogy, see http://books.google.co.nz/books?id=t-OQO3Wk-JsC&pg=PA62&...

A problem with using CH2I2 (density 3.325 gm/cc) or other heavy liquid for separating out grains of Au or Pt in river or beach alluvia is that, besides grains of silica and silicate and carbonate minerals (densities usually below about 3 gm/cc), the raw alluvia may also contain grains of magnetite, Fe3O4, density 4.5 gm/cc (possibly along with some hematite, Fe2O3, and ilmenite, FeTiO3, of slightly lesser density), especially if it contains any "black sand". However, after sinking along with the grains of Au and Pt in the CH2I2, the magnetite can be simply separated from the Au (and Pt) by applying a strong magnet, preferably one sufficiently strong to also attract any hematite and ilmenite which are much less strongly ferromagnetic than magnetite.

JohnWW - 3-8-2010 at 08:21

(Or, if there is a substantial amount of grains of magnetite, ilmenite, or hematite present in the sample, these could be removed by the magnet in advance of immersion in CH2I2 to remove the lighter gangue materials).

densest - 4-8-2010 at 08:58

Cesium acetate, according to an old Chem Rubber Handbook, will dissolve 946 g in 100ml of water

Besides the cost of c(a)esium there are probably other reasons it's not commonly used as a dense liquid. I'd guess that it's a pretty strong base. Still, an aqueous solution with a specific gravity over 10! Off the top of my head, I don't know if there's a strong acid which could be added to bring it closer to neutral. All the Cs salts of strong acids are considerably less soluble. Ion sizes & charges & crystal packing reasons?

Anyway, I thought I'd bring this up as a (implausible) alternative or addition.

Nicodem - 4-8-2010 at 12:53

Quote: Originally posted by densest

Cesium acetate, according to an old Chem Rubber Handbook, will dissolve 946 g in 100ml of water
...
Still, an aqueous solution with a specific gravity over 10!

Where did you get that number of 10? It makes no sense. If 946 g of something dissolve in 100 mL of a solvent then the final volume of the solution would have to be no more than 100 mL to give a density of 10 kg/L!

densest - 4-8-2010 at 13:13

Hmmmm..... probably from a brain short circuit. The solid is 2.423 g/cm3. Oh well... too little sleep last night.

It would be interesting to see what the volume would be... is there any way of predicting that? Or is it all tied to how the water molecules arrange themselves around the various ions & molecules, disassociation constants, something which isn't known a priori?

Anyway, the CH2I2 thread is quite interesting. Just ignore this bit of blather, sorry.

Eclectic - 5-8-2010 at 01:27

http://www.lycaeum.org/~mulga/silico.html

Lithium Silicotungstate is also used in specific gravity separation liquid.

Pretty much any soluble tungstate can be use in the prep.

Mush - 27-8-2011 at 08:48

This is Google translation of JAN VACEK's patent ( CS208568 ).
It might be interesting to us.

DESCRIPTION OF THE INVENTION
The copyright CERTIFICATE
208 568
(61)
(23) Exhibition priority
(22) Registered 02 07 79 (21) PV 4621-79
(40) Published 31 10 80 (45) Issued 01 12 83
(51) Int. C '- C 07 C 21/02
OFFICE OF INVENTIONS RO
AND DISCOVERIES
(75)
By JAN invention VACEK ing, BRNO
(54) Production method metylenjodidu
1
The invention relates to the production of aluminum metal metylenjodidu reaction with iodine and subsequent konveraí nascent iodine oxide with methylene chloride.
A common way to prepare is to reduce metylenjodidu jodoformu or methods based on the reaction of methylene chloride and sodium iodide, or aluminum. Hoffman (Annalen.der Chemistry 115, p. 267) and Butlerov (Annalee de Physique et de Chitnie) describe the preparation of metylenjodidu jodoformu. Henry (Beriohte 24 - Referate) (and Perkin and Scarborough) (J.Chem.Soc. 119, 1408) describe the preparation of sodium iodide and methylene chloride. Laurel et al. <Pat. No. 144 027) 2 metylenjodid preparing alumina and methylene iodide. Unlike Gustavson (Annalen der Chemie 172, p. 173) prepared in a solution of iodine oxide. As a reaction environment metylenjodid used directly. Even in this case the reaction proceeds too low (almost around 60%), currently underway for other competing reactions that result in a reduction of the proceeds and are the cause of difficult isolation of the product. Cs. author's certificate No. 205568 describes the preparation of iodide metylenjodidu alumina and methylene chloride, and aluminum iodide preparation is done in Solvents, and conversion of aromatic and aliphatic methylene chloride in a solvent or alycykliokém. Although this method gives yields of about 85% and production is safe ', the exchange type of Solvents in different stages of technological difficulties.
The preparation method of the present invention eliminates metylenjodidu nellrýhodu connected and using 208 808
various solvents with MS. Copyright Licence No. 205568th Its essence Ilpočívá that the preparation of iodine oxide and following conversion to e metylenohloridem done in an environment cykloparafiniokých hydrocarbons on the number of atoms per molecule 5 to 10 or mixtures thereof and preferably oyklohexanu. It managed to find suitable Solvents, which takes place with sufficient speed and reaction of iodine and aluminum which is also inert in terms of reaction with methylene iodide aluminum, no significantly simplified the site of production technology and also the fact that there is no loss of handling aluminum iodide occurred while an increase in yield. Solvents are suitable as oyklopexatinioká hydrocarbons. In particular, cyclohexane. When preparing Jedidah oxide at the beginning of reaction when the temperature reaches boiling point short period exothermiaké spontaneous reaction, but soon relents and the next phase of the reaction mixture be přihřívat. In the case of iodine in a great mood operating conditions would be dangerous vykypaní reaction mixture. Heating boiler is sufficient content to 40 to 60 ° C and the reaction mixture kept stirring at this temperature for 0.5 to 1 hour and then heating to refiuxu. Alternatively, can use a mild cooling. To reduce turbulence reactions may be iodine or aluminum or both components dosed in parts. In laboratory conditions, this period of increasing reflex occurs only at the beginning of the reaction after reaching the boiling temperature of the reaction mixture. You can do the same so that metylenohlorid will be added to the reaction mixture. after spontaneous exotexiniaká reaction of iodine and aluminum.

P r s a l and d 1
The reaction čtyřndlá bank of 500 ml equipped with stirrer, reflux condenser, thermometer
rem oil bath and heated to 100 g of iodine present, 8 g aluminum meal and 400 ml of anhydrous cyclohexane. Contents of flask while stirring slowly heated to reYluxu. After reaching the boiling temperature of the contents of e retluxuje for 3-4 hours while intensive stirring. After this time there is complete reaction of the components and discoloration of the reaction mixture. After the reaction mixture is cooled to 40 ° C, the drip slowly admits 35 g dry metylenohloridu. Admission rate is regulated so that about 3 / 4 total metalenchloridu joined within 1 hours. The rest is added slowly for another hour. Ee reaction temperature maintained between 40 to 50 ° C. Then the contents stirred at this temperature for 2 hours, whereupon the reaction mixture was cooled and e to 20 00 and dropped out of aluminum chloride is filtered off and washed with 50 ml ogklohexanu. E Piltrát washed three times with 500 m1 of water and concentrated using a box of 3 to 5 TP. Tars in the same flask still exaggerates the steam to remove absorbed ayklohexanu. Receives two factions. Main frakoe, 'laying remains in the distillation flask was separated and washed once hydrosiřičitanu native solution and three times with clean water. Gets, 80 g of pure metylenjodidu. Oyklohexanová fraction distilling off process e same way. Calculated according to the density are shown to contain metylenjodidu. The total yield is about 95% of theory to iodine. Cyklohexanová factions in production can be added to the next batch.

P r s a l and d 2
Equipment and raw materials used are the same as in Example 1 The difference lies in the fact that conversion to lead at 75 to 80 00 and metylenahlorid to rakční compounds dosed in a solution of 50 m1 oyklohexanu. The total conversion time is ~ oháním place for 1 hour. Isolation is provádf as in Example 1 Yield 91.5% response teorie.na used iodine.

P r s a l and d 3
Same equipment as in example 1 The present reaction flask 350 ml of dry cyclohexane, 100 g of iodine and 7.2 g aluminum grits. Contents of the flask is slowly heated to boiling point, the reaction mixture. After racing exotherrnní spontaneous reaction to the reaction mixture is added through the reflux condenser 34 g of dry metylenahloridu for about 0.5 hours adding speed is initially much higher than at the end. After adding all the methylene chloride, the reaction mixture maintained a slight reflex for 2 hours. The method of isolation is the same as in Example 1 Reaction yield is about 92.5% tetorie used for iodine.

P R i k 1 and d 4
Apparatus as in Example 1 The reaction flask with 300 ml of dry submit cyklooktanu, 100 g of iodine and 5 g of anhydrous aluminum chloride. After 1 / 2 hour stirring at room temperature is added 7.2 g aluminum grits. After racing exothermické spontaneous reaction to the reaction mixture slowly add 34 g of dry metylenahloridu. Cooling temperature of the reaction maintained at 50 to 60 ° C. At the end of the place to be cooling slightly přihřívat. After you have added. e metylenhhloridu all contents of the flask stirred at 60 ° for 2 hours. After the reaction mixture is cooled and filtered. Aluminum chloride, washed with 100 ml e cyklooktanu. The filtrate was washed with a solution pyroaiřičitanu and water and concentrated by distillation at an oil bath until the bath temperature 160 ° C. Tars, after cooling is separated from the remaining ěyklooktanu and cleans e same options as to how. manner as in Example 1 The yield is 89% theory.
P R E D E E N T Y Y and Z B Z U
The method of production of aluminum metal metylenjodidu reaction with iodine and subsequent conversion of nascent iodine oxide and metylnchloridem marked by the preparation of iodine oxide and methylene chloride and náaledujíoí conversion is done in an environment cykloparafinických hydrocarbons on the number of atoms per molecule 5 to 10 or mixtures thereof and preferably cyklohessnu.

[Edited on 27-8-2011 by Mush]

Mush - 27-8-2011 at 09:13

CS212812

ČESKOSLOVĚNfKÁ

SOCIALIST

R E P U d L 1 K A

(1S)
OFFICE FOR INVENTIONS
DESCRIPTION invented
The copyright CERTIFICATE
212812
(61)
(23) Exhibition priority
(22) Registered 28 03 80 (21) PV 2175-80
(51) LNT. CL '
C 07 C 21/02
And Od1EVY
(40) Published 31 08 81 (45) Issued 01 12 83
(75)
By JAN invention VACEK ing, BRNO
(54) The mode of production 'metylenjodidu

1 '
The invention relates to the production of aluminum metal metylenjodidu reaction with iodine and subsequent conversion of the resulting aluminum iodide d methylene chloride.
Methods of preparation metylenjodidu reduction jodoformu are now only historical significance. Now widely used methods are based on the reaction of methylene iodide and aluminum differ mutually only way to prepare aluminum iodide and reaction environment
the conversion and metylenahloridem. Laurel et al. (Pat. No. 144 027) is used as a reaction environment itself metylenjodid. Due to the considerable reactivity metylenjodidu metal aluminum has a normal temperature is used as the reaction environment metylenjodidu inappropriate. Author's Certificate (205 568) describes the preparation of iodine oxide in an aromatic solvent and konnversi with $ etylenahloridem in alivatickém or alj.vatickém Solvents. Replacement of the type of solvents in the individual reaction steps, however, is technologically challenging. Author's Certificate (205 568), which builds on the previous PV, used as a reaction environ said the two reaction stages cýkloparafiniaké hydrocarbons. Getting clean cykloparaficnického ever encountered hydrocarbon production and trade difficulties and was therefore trying to find a suitable reaction condi ky + so that it can use normal commercially doatupné, Solvents.
Preparation metylenjodidu the invention eliminates the disadvantages associated PV 4621-79
with the availability ayklohexanu and is characterized by the fact that the preparation of iodine oxide and conversion of the following bases lenablorídem be carried out in an environment of paraffinic hydrocarbons of coal aia 812
ing 5 to 10, or Jejioh mixtures, or mixtures of hydrocarbons parafinovýoh and oykloparafinovýnh
the number of carbon atoms 5 to 10 Use of these hydrocarbons is possible that the tray can be both reactions, ie, how the creation of iodine oxide, and the following conversion and metylenohloridem carried out concurrently. This will prevent sticking iodide oxide of aluminum metal on the surface due to its small řozpuetnosti used in Solvents. Reakoe conducted in this manner is very lively and well-regulated speed inlet methylene chloride. Example
As a reaction environment with medical uses gasoline, and free from aromatic hydrocarbons and lower nenaeycanýoh parafinickýoh factions. For this purpose, the raw medical refluzuje gasoline for 2 hours e anhydrous aluminum chloride and metylenohloridem relative oca 20 wt. parts gasoline to 1 wt. piece of aluminum chloride and metylenohloridu. Then the liquid complex forgive and content předeetiluje. Factions in BV 550 can be separated and used in the reaction e fraction bv 55-90 00th
The čtyřhrdlé reaction flask of 500 m1. equipped with stirrer, reflux condenser, thermometer and a drip shall be submitted with stirring 250 ml gasoline fractions, 100 g of iodine and 5 8 aluminum chloride. Content is at normal temperature sweeps 15 min and then add?, 2 g of aluminum grits. The temperature spontaneously appear between 30 and 40 00 Once teplots'přestane spontaneously rise begins to slow přikapávat metylenohlorid (34 g). Response to live and starts cooling the reaction temperature maintained at 45 ° C d50 Time methylene chloride dosage DC 1.5 to 2 hours. At the end of the reaction to be slightly přihřívat. When added vešekerého metylenohloridu reaction flask contents are still 1 hour, stirred at 50 ° C. Then the contents cool and decant. Gooey aluminum chloride is mixed with 100 ml of gasoline frakoe.a to decant. Petrol solution was washed with a solution pyrosiřičitanu stab and then with water and concentrated from the oil bath until the bath temperature 150 ° C. Tars, after cooling separates from light gas phase. Gets around 89 g of crude metylenjodidu that the Kono and shaken out. sulfuric acid solution and water pyrosiřičitanu provide about 80 g of pure metylenjodidu.

MET BEFORE THE INVENTION
The method of production of aluminum metal metylenjodidu reaction with iodine and subsequent konveraí nascent iodine alumina metylenahloridem,, marked by the preparation of iodine oxide and following conversion to perform in an environment metylenohloridem parafiniakýoh uhlovodír.
ing, the number of carbons, 5 to 10 or blends or mixtures of hydrocarbons aykloparafiniokýdt paratiniakýoh and the number of carbon atoms of up to 10

. Aia 812
ing 5 to 10, or Jejioh mixtures, or mixtures of hydrocarbons parafinovýoh and oykloparafinovýnh
the number of carbon atoms 5 to 10 Use of these hydrocarbons is possible that the tray can be both reactions, ie, how the creation of iodine oxide, and the following conversion and metylenohloridem carried out concurrently. This will prevent sticking iodide oxide of aluminum metal on the surface due to its small řozpuetnosti used in Solvents. Reakoe conducted in this manner is very lively and well-regulated speed inlet methylene chloride. Example
As a reaction environment with medical uses gasoline, and free from aromatic hydrocarbons and lower nenaeycanýoh parafinickýoh factions. For this purpose, the raw medical refluzuje gasoline for 2 hours e anhydrous aluminum chloride and metylenohloridem relative oca 20 wt. parts gasoline to 1 wt. piece of aluminum chloride and metylenohloridu. Then the liquid complex forgive and content předeetiluje. Factions in BV 550 can be separated and used in the reaction e fraction bv 55-90 00th
The čtyřhrdlé reaction flask of 500 m1. equipped with stirrer, reflux condenser, thermometer and a drip shall be submitted with stirring 250 ml gasoline fractions, 100 g of iodine and 5 8 aluminum chloride. Content is at normal temperature sweeps 15 min and then add?, 2 g of aluminum grits. The temperature spontaneously appear between 30 and 40 00 Once teplots'přestane spontaneously rise begins to slow přikapávat metylenohlorid (34 g). Response to live and starts cooling the reaction temperature maintained at 45 ° C d50 Time methylene chloride dosage DC 1.5 to 2 hours. At the end of the reaction to be slightly přihřívat. When added vešekerého metylenohloridu reaction flask contents are still 1 hour, stirred at 50 ° C. Then the contents cool and decant. Gooey aluminum chloride is mixed with 100 ml of gasoline frakoe.a to decant. Petrol solution was washed with a solution pyrosiřičitanu stab and then with water and concentrated from the oil bath until the bath temperature 150 ° C. Tars, after cooling separates from light gas phase. Gets around 89 g of crude metylenjodidu that the Kono and shaken out. sulfuric acid solution and water pyrosiřičitanu provide about 80 g of pure metylenjodidu.

MET BEFORE THE INVENTION
The method of production of aluminum metal metylenjodidu reaction with iodine and subsequent konveraí nascent iodine alumina metylenahloridem,, marked by the preparation of iodine oxide and following conversion to perform in an environment metylenohloridem parafiniakýoh uhlovodír.
ing, the number of carbons, 5 to 10 or blends or mixtures of hydrocarbons aykloparafiniokýdt paratiniakýoh and the number of carbon atoms to 10 F

Mush - 27-8-2011 at 09:22

CS205568

CZECHOSLOVAK

SOCIALIST

R E P U B L I K A

(19)
DESCRIPTION OF THE INVENTION
The copyright CERTIFICATES
205 568
(11) (B1)
(61)
(23) Exhibition priority
(22), subscribed 01 11 78
(21) PV 7121-78
OFFICE FOR INVENTIONS (40) Published on 29 08 80
(45) Issued
AND DISCOVERIES 01 09 83
(75)
By JAN invention VACEK ing, BRNO
(51) Int. Cl. 3 C 07 C 21102
(54) Production method metylenjodidu
The invention relates to a method metylenjodidu production of aluminum, iodine and metylenohloridu. They are known and described various methods of preparation metylenjodidu. Technological importance
However, the only ways to achieve based on redukoi jodoformu or methods based on the reaction metylenohloridu and sodium iodide, or aluminum iodide. Hoffman (Annalen der Chemie 115, p. 267) and Butlerov (Annales de Chimie et de Physigue / 3 /, 58, 313) describe the preparation of metylenjodidu jodoformu. Henry (Berichte 24 - Referate) and Perkin and Scarborough (J. Chem. Soc 119, 1408) describe the preparation of methylene chloride and sodium iodide. Guatavson (Annalen der Chemie 172, p. 173) based on the preparation of iodine oxide and metylenohloridu.
The disadvantage of the method of manufacture jodoformu is already evident, from the very reaction stoichiometry, which leads to loss of one iodine atom. Moreover, in case redukoe areanitými salts, ie a method which is industrially the most spread creates highly toxic waste, whose disposal is difficult. The method based on methylene chloride and sodium iodide gives low yields (around 60%) and requires long reaction times. Progress is the way of production, designed by Laurel et al. (Author's certificate No. 144027), which is based on the reaction metylenohloridu iodide and aluminum. Unlike Gustavson, however, are preparing aluminum iodide in solution. As a reaction environment metylenjodid used directly, which currently is carried out by conversion of alumina and methylene iodide. The proceeds, however, in this case is relatively low. In addition, there is sometimes a reaction vykypéní content boiler and thus to a considerable loss of iodine and air pollution. The reason it is difficult to use the reaction, where submitted to a full dose of iodine in the environment metylenjodidu is fed powdered aluminum. Reaction of iodine and aluminum is highly exothermic and cooling is maintained at 100 to 120 ° C. After adding each batch of aluminum reaction due to the metal surface neaktivovaného immediate starts. This content boilers and easily supercooled to the reaction started again be content boiler warm. When a sudden reaction shot it difficult to manage content utshladit boiler to prevent boil over ejaculation and iodine vapor into the atmosphere. Another drawback of this method lies in the fact that aluminum přidhází metylenjodidem into contact and, while these substances to react as fast as ordinary temperatures. These side reactions have resulted in both a reduction in yield due to direct losses of iodine and that gives rise to various impurities, which makes it difficult to isolate the product, thereby further reducing yield.
The above method eliminates the drawbacks of production metylenjodidu the invention indicated by the first instance prepare iodine oxide and iodine reaction of aluminum in the environment of liquid aromatic hydrocarbon such as benzene, chlorobenzene, toluene, xylene or their mixtures at temperatures between 20 and 00 to the boiling point the Solvents, whereupon the liquid aromatic hydrocarbon replace other inert Solvents, such as saturated or metylenjodid parafinioký cykloparafinický or hydrocarbon or mixtures thereof, such as gasoline extraction, petroleum ether and the reaction mixture is introduced methylene chloride at 10 to 60 ° C HEIGHT
lot at 35 ° C and the resulting metylenjodid is separated from the aluminum chloride and read. If changing the environment of the aromatic hydrocarbon metylenjodid made the first displacement of the aromatic hydrocarbon Solvents are nemísícím, or just limited to mixing with metylenjodidem such as n-hexane, pentane, cyclohexane, however, with the advantage of light petroleum. The resulting gradual metylenjodid to clean washing pyrosiňičitanem alkali metal, sulfuric acid and water.
In order to eliminate the above disadvantages popsanýoh, it is of low yield and dangerous outburst of iodine vapor reaction of the present invention is adjusted so that they submit all aluminum, with appropriate rozpuatidlem and mixed into this suspension is added iodine. The reaction is spontaneously starts within a few minutes at room temperature. The fact that aluminum is the next stage, a surfactant, occurs when each new dose of iodine to start immediate reaction and its course is easy to use. Danger outpouring of iodine vapor is completely odatraňěno, as in the reaction mixture is not an excess of free iodine and as a reaction environment is not used metylenjodid that decomposition also releases iodine.
Selection of solvents as the reaction environment is very limited. Completely inappropriate and oxygen compounds are arbitrarily bound oxygen and other compounds that may be an electron pair donor, such as amines. Also, chlorinated paraffins due to reactions and aluminum iodide out of the question. Virtually failed nalézt.žádflé Solvents suitable in which the reaction proceeded satisfactorily in both stages. Solvents in which a well is being prepared iodine oxide, are unsuitable for conversion to methylene chloride, which react strongly in the sense in counters-Crafts reaction. Solvents in which it conducted a satisfactory conversion of iodine oxide and metylenohloridem are unsuitable for first grade. Reactions have either not gone at all or only very slowly. Universal Solvents, which would also be appropriate komerňních reasons for use could not be found. For the first stage comes into consideration::. Only benzene, toluene, xylene and chlorobenzene is particularly advantageous. For the second reaction stage are suitable paraffinic or cykloparafinické hydrocarbons or mixtures thereof. Unsuitable are already branched hydrocarbons. Fairly good yields were achieved with extraction gasoline. It is also possible to carry out the reaction in carbon disulfide, but most Solvents for the second stage is the product itself, it is metylnjodid.
The solvents for the first stage is the best proven chlorobenzene. Reaction it is very smooth and its relatively high boiling point is advantageous for the reaction and relatively easy to regenerate. For the next phase, however, it must be quantitatively removed. Due to the considerable reactivity jodudu oxide to the atmosphere of isolation is not desirable in dry or semi-dry state. Removal of the parent chlorobenzene multiple decantation inert Solvents is considerable specific weight of iodine oxide and the associated problems and stirring slehlého product difficult to solve. It is therefore desirable to remove chlorobenzene continuously stirring. The displacement of chlorobenzene mixed suspension of iodine oxide has proven petroleum use. Simultaneously attracting petroleum and sucks him his chlorobenzene solution, according to the amount of petroleum achieves the desired degree of displacement. The rest of chlorobenzene from the reaction mixture with light petroleum submitted eventually displaced metylenjodidem with petroleum ether which is miscible very limited. Due to the high specific weight metylenjodidu no longer the strong confinement of crystalline iodine oxide and can therefore stop mixing, keep the two completely separate the liquid phase and upper phase petroléterovou along with small amounts metylenjodidu using siphon download. After separation of the two phases in the lower děličce metylenjodidová phase runs back into the reaction vessel.
In addition to increasing yield and avoid the risk of emissions of iodine vapor is a manufacturing method of the invention advantageous also in terms of isolation of the final product. Under current procedure, the reaction mixture is impregnated into the cold water. Although this is the decomposition of aluminum chloride, but all impurities present at the same time go into metylenjodidové phase. Isolation of product from this colorful mixture is very difficult and unprofitable and virtually done only lengthy steam distillation.
Insulation product according to the invention consists in filtering the main portion metylenjodidu. This fraction gradually vytřepáním pyrosiřičitanu stab aqueous solution, sulfuric acid and water and vysršením over anhydrous calcium chloride directly provide clean metylenjodid,
with it in a number of around 65% for hatching iodine. The rest of cake aluminum chloride, which in itself still retains quite a considerable amount metylenjodidu was washed with petroleum ether and the filtrate containing dissolved metylenjodid Clears the same way, it is a gradual solution vytřepáním pyrosiřičitanu solution, concentrated sulfuric acid a. water. Finally, the concentration of the filtrate initially performed at atmospheric pressure and at the end using a vacuum. To obtain pure products gj this fraction would require a strong concentrated at higher temperatures and higher
vacuum. In the fighting over, this is not necessary since this guaranteed product that has a specific weight of 2.5 to 2.9 g/cm3 can be used as a reaction environment for further production. The remaining cake can be aluminum chloride after washing with chlorinated hydrocarbon, such as raetylenohloridem after drying and used as a catalyst for Friedel-Crafts reaction, etc. The quality of the color and reactivity with water is very good.

• feel familiar to 1 and
The čtyřhrdlé sulfonační flask of 0.5 liters, equipped with stirrer, thermometer, cap
rem against humidity (sulfuric acid) and cooling water bath in the first degree and even fitted for the next stage exhaust filter for separating a straw mixture petroléterové
and drip to the present metylenahlorid práškovitého 29.6 grams of aluminum and 100 ml of dry chlorobenzene.
Stirring and cooling water bath is added in batches (about 25 g) 400 g solid iodine. Start dosing at normal temperature. Once the reaction temperature exceeds 80 ° C, add another dose until after the drop to 70 ° C. In this way, adding approximately 300 g of iodine. Last 100 g of iodine is added for ever smaller doses with increasing reaction temperature and without external cooling. The last batch is added at a temperature around 130 ° C. Unconditionally then begins přihřívat content and keep about 15-20 minutes around 140 ° C. This causes a reaction of the last traces of aluminum, which is the next phase of the reaction side. Keeping the right temperature regime prevents formation of iodine oxide Kruat stěnáooh the reaction flask. Once the purple color disappears, discontinue heating and content allow to drain for mixing cool. When the temperature drops 70 ° C PDD dochladí the content of the water bath to help (preferably ice to reduce the vapor pressure petroiéteru).
After cooling, a dense suspension of 100 ml of light petroleum and dried by vacuum filtration and the siphon sucked stirring solution of chlorobenzene in petroleum. At the same time, the following either continually or in parts petroleum ether to the reaction flask contents mixes.
• removed chlorobenzene consumes 400 to 500 petroleum 4. Then the suction stops and the reaction suspension is added metylenjodidu weighed amount, roughly 300 to 350 g. After mixing the contents of the reaction cell of about 0.5 hours left in peace, then downloaded to a straw filter dividing the upper layer of petroleum along with small amounts metylenjodidu. After separation. phases metylenjodid run back into the reaction flask. Then warms up to the content
35 ° C and begins to drip pomooí dosed dry metylenohlorid. At the same time confuses the heating bath cooling bath. fiyohlost dosed metylenohloridu intensity and smoothed it going, so that reaction temperature was maintained between 35 to 40 ° C and not leak when the seal in moisture bublačce no gas or only in small quantities. The drip when it submitted 140 g metylenohloridu. The last 10 g metylenohloridu is fed polished reakoe without external water bath. Once the reaction temperature begins to drop while bublačkou starts leaking gas supply is interrupted another metylenohloridu. Reaction flask contents are then stirred for 0.5 hours at a temperature around 35 ° C.
• reakoi this stage can either suspend or heat the contents of the flask at 40 to 50 ° C and the crude product filtered through a glass frit. The rest of cake to wash nučí about 600 ml light petroleum, however Collect the filtrate separated from the crude product. The crude product is poured into 1 l divider and add to it about 0.5 1 vody.a about 0.5 grams of sodium pyrosiřičitanu. After shaking several times with colorless contents dividers. In the negative case, add a small amount pyrosiřičitanu. After phase separation the lower layer is put away in the second divider and add about 150 ml of concentrated sulfuric acid. After shaking several times to keep the contents separate and lower phase are put away back to clean the first divider, where metylenjodid shaken 3 times with 0.5 1 of pure water. Slightly yellowish, almost transparent metylenjodid is dried over granular anhydrous calcium chloride.
Petroléterový filtrate in the same manner and same amount of raw materials as the main wash product. Then the oil bath in distilled petroleum ether bath temperature 140 ° C and finally after replacing the master bath at the same temperature and vacuum of about 100 to = rest of distilled petroleum. The product obtained according to specific gravity, assuming that it is only a mixture of petroleum and metylenjodidu be converted into content metylenjodidu. After deducting metylenjodidu used as an environment is found to yield the overall reaction. According to the method described, yield ranges between 82 to 85% of theory on the amount of iodine.
P R E D M S T V Y N A L E Z U
1st Metylenjodidu manufacturing method of metal aluminum, iodine, and methylene chloride, indicated by
that in the first instance prepare iodine oxide and iodine reaction of aluminum in the environment of liquid aromatic hydrocarbon such as benzene, chlorobenzene, toluene, xylene or their mixtures at temperatures from 20 ° C to the boiling point of Solvents, whereupon the liquid aromatic hydrocarbon replaces another inert Solvents such as metylenjodid or paraffinic or cjCkloparafinický hydrocarbon or a mixture such as gasoline extraction, petroleum ether and the reaction mixture is introduced methylene chloride at 10 to 60 ° C, preferably at 35 ° C and the resulting metylenjodid separates from chlinitého chloride and clean.

2nd Metylenjodidu manufacturing method in accordance with point 1, marked by confusion in the environment of the aromatic hydrocarbon in the first metylenjddid will squeeze the aromatic hydrocarbon Solvents are nemísícím, or just limited to mixing with metylenjodidem, such as n-hexane, pentane, cyclohexane, however, with the advantage of light petroleum.

3rd Metylenjodidu manufacturing method in accordance with point 1 and 2, indicated by the resulting metylenjodid
to clean the gradual washing pyrosiřičitanem alkali metal, sulfuric acid and water.

Assured Fish - 28-5-2016 at 23:14

Would it not be possible to react methylene glycol with hydriodic acid to get diiodomethne? Im pretty sure formaldehyde forms an equalibrium with methylene glycol that varies at different temperatures and concentrations, but if thats not viable could you simply react dichloromethane with sodium hydroxide or potassium hydroxide to form sodium/potassium chloride and then distill off the glycol and then react with hydriodic acid. If hydriodic acid is illegal in your country then maybe make anhydrous methylene glycol and then react that with phosphorous triiodide.

CuReUS - 29-5-2016 at 02:54

I have had this question for a long time. Could you reduce iodoform to DIM using an alkaline glucose solution ?

[Edited on 29-5-2016 by CuReUS]

PHILOU Zrealone - 8-6-2016 at 11:25

Maybe Silver malonate + I2 may give CH2I2 upon heating?

Silver carboxylate heating with halogen allows for decarboxylation and formation of alkyl halide and silver halide...

CH2(-CO2Ag)2 + 2 I2 -heat-> CH2I2 + 2 CO2(g) + 2 AgI(s)

Boffis - 8-6-2016 at 23:23

@ CuReUS, I have looked at the reductions several times as I use methylene diiodide in mineralogy and its very expensive. It appears that there are many reducing agents that can accomplish the reduction, the problem is stopping them at the removal of one iodine. An alkaline glucose solution looks like a reasonable option provided there isn't a large excess of alkali.

The main issue I encountered seemed to be the protecting effect of the first formed CH2I2 on the remaining iodoform, the former dissolves the latter taking it into the organic phase. I have always though that a organic-soluble reducing agent would be helpful. Any ideas?

CuReUS - 9-6-2016 at 01:57

Quote: Originally posted by Boffis

The main issue I encountered seemed to be the protecting effect of the first formed CH2I2 on the remaining iodoform, the former dissolves the latter taking it into the organic phase. I have always though that a organic-soluble reducing agent would be helpful. Any ideas?

Why use an organic solvent at all ? we could run the reaction similar to a benedict's test without the Cu ions.Just boil the iodoform in the alkali-glucose solution.Since DIM is more soluble in water(1240 mg/dl) than iodoform(100 mg/dl),it will slowly dissolve in the aq solution whereas the iodoform will stay behind,thus pushing the equilibrium forward.

PHILOU Zrealone - 9-6-2016 at 03:04

Quote: Originally posted by CuReUS

Quote: Originally posted by Boffis

Why not simply cold distil/condense it away?
CH2I2 must be much more volatile than CHI3...thus shifting equilibrium...

CuReUS - 10-6-2016 at 01:35

Quote: Originally posted by PHILOU Zrealone

Why not simply cold distil/condense it away?
CH2I2 must be much more volatile than CHI3...thus shifting equilibrium...

because the glucose-alkali reduction of iodoform will be done in an aqueous solution and the boiling point of DIM is 181'C

clearly_not_atara - 10-6-2016 at 13:49

Dichloroacetic acid or its esters should undergo the Finkelstein reaction far more rapidly than dichloromethane. From:

https://en.wikipedia.org/wiki/Finkelstein_reaction

you can see that chloroacetone reacts about 200x as fast as MeCl.

http://en.wikipedia.org/wiki/Dichloroacetic_acid

Quote:

DCA is prepared from chloral hydrate also by the reaction with calcium carbonate and sodium cyanide in water followed by acidifying with hydrochloric acid.

Might this be one of the odd reactions (cf. benzoin condensation) where thiamine is a useful stand-in for cyanide?

Boffis - 10-6-2016 at 14:39

Dichloroacetic acid is readily prepared from commercially available trichloroacetic acid by dissolving zinc in it. Instead of hydrogen being evolved the acid looses a chlorine atom instead. I have a reference somewhere for this.

So now you can get DCA and lets assume the Finkelstein reaction works a treat on it, are you sure you can get it to decarboxylate readily or does this happen spontaneously as with some other substituted acetic acids ie nitroacetic acids?

PHILOU Zrealone - 11-6-2016 at 10:22

Quote: Originally posted by CuReUS

Quote: Originally posted by PHILOU Zrealone

Why not simply cold distil/condense it away?
CH2I2 must be much more volatile than CHI3...thus shifting equilibrium...

because the glucose-alkali reduction of iodoform will be done in an aqueous solution and the boiling point of DIM is 181'C

OK thanks!
Glucose solution with NaOH could boil very much higher than 100°C...but 181°C is maybe too high.

For the rest glycol might be used as a high boiling solvent maybe forming an azeotrope with CH2I2 (CH2Cl2 and CH2Br2 do form azeotrope with it)...

[Edited on 11-6-2016 by PHILOU Zrealone]