foxy2
(Hive Addict)
07-23-01 13:58
No 198306
      Iodination of Vanillin
(Rated as: excellent)
    

Here is an easy route to 5-iodovanillin for anyone interested.  This adds to the Vanillin --> "something interesting" possibilities.  Also its is a possibility for 2-CI.
Foxy

Aromatic iodination in aqueous solution. A new lease of life for aqueous potassium dichloroiodate

Tetrahedron Letters
Volume 42, Issue 11                   
11 March 2001
Pages 2089-2092

During experiments involving the iodination of vanillin, it was noted that different experimental procedures could markedly affect the outcome of the reaction. These procedures included the addition of the substrate as a solution or solid to the aqueous KICl2 solution or vice versa. In the case where an aqueous solution of vanillin (10 mmol, 0.2 M) was added to the KICl2 solution (2.2 equivalents, 0.73 M) the reaction mixture became very darkly colored and a darkly colored precipitate was obtained. This was isolated by filtration, treated with aqueous sodium thiosulfate and recrystallized from aqueous ethanol to give 5-iodovanillin in 22% yield as slightly brown crystals. When the same experiment was repeated but by adding the KICl2 solution to an aqueous solution of vanillin (10-50 mmol), the reaction mixture did not become darkly colored and a slightly gray product was precipitated. Isolation of this product and purification in an identical manner to that above gave an 80% yield of colorless 5-iodovanilin. Adding vanillin as a solid to an aqueous solution of KICl2 did not result in the formation of a darkly colored precipitated product, but did give an overall lower yield of purified product (50-55%).



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    Dr_Sister
(Hive Bee)
07-23-01 20:42
No 198384
      Re: Iodination of Vanillin     

this avoids having to mess around w/ nasty Br2? and can be used as an intermediate to hydroxyvanillin?

potassium dichloroiodate is readily accesible? not familiar w/ sorry, making sure i am on the same page.

7.10.01
 
 
 
 
    obituary
(Hive Addict)
07-23-01 21:24
No 198396
      Re: Iodination of Vanillin     

could you make the KICl2 by mixing KI and Cl2 in aqueous phase?   (works for KBr3 by KBr + Br2)
 
 
 
 
    foxy2
(Hive Addict)
07-23-01 21:32
No 198400
      Re: Iodination of Vanillin     

Anyone? The following may have some info.
I really have no idea about KICl2.
You will probably have to look in the references given in the article to find out how to make it.

http://translate.google.com/translate?hl=en&sl=pt&u=http%3A//www.iq.ufrj.br/pgqo/Docentes/Simon_Garden/simon.html&prev=/search?q=KICl2&hl=en&safe=off

GARDEN, S. J., TORRES, J. C., LIMA, A. S., LIMA, E. L. S., MELO, S. C. S., PINTO, A. C.
Iodação de sistemas aromáticos utilizando dicloroiodato de potássio (KICl2) In: 21a Reunião Anual da Sociedade Brasileira de
Química, 1998, Poços de Caldas.
  Resumos da 21a Reunião Anual da Sociedade Brasileira de Química. , 1998. v.1.

   Palavras-chave: Iodação, KICl2, Imidazóis, Iodoimidazóis

   Áreas do conhecimento : Síntese Orgânica

   Setores de atividade : Industria Farmaceutica, Industria Quimica

   Referências adicionais : Brasil/Português. Meio de divulgação: Impresso
Trabalho realizado em cooperação com os professores Angelo C. Pinto e Simon J Garden

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    Osmium
(Stoni's sexual toy)
07-23-01 21:32
No 198399
      Re: Iodination of Vanillin     

> could you make the KICl2 by mixing KI and Cl2 in aqueous
> phase?   (works for KBr3 by KBr + Br2)

IMHO yes.

Maybe KIBr2 would work too, easier to prepare (?) than KICl2 by in-situ oxidation of a KI and KBr solution. Anybody?
 
 
 
 
    Antoncho
(Official Hive Translator)
07-24-01 01:25
No 198427
      Re: Iodination of Vanillin     


> could you make the KICl2 by mixing KI and Cl2 in aqueous
> phase?   (works for KBr3 by KBr + Br2)




Chlorine will instantly liberate I2 upon addition to KI so it's like the same as adding I2 to some KClfrown You probably need some ICl to make that stuff.

Antoncho

 
 
 
 
    foxy2
(Hive Addict)
07-24-01 02:47
No 198438
      Re: Iodination of Vanillin     

Antoncho is right about Cl2 produceing I2 and KCl.

Thats a real bummer, I wonder how this reagent is made?

Do Your Part To Win The War
 
 
 
 
    ZyGoat
(Stranger)
07-25-01 19:36
No 198873
      Re: Iodination of Vanillin
(Rated as: excellent)
    

Patent US4465864 

This invention relates to a process for the hydroxylation of an aromatic compound.

Lignin derived aromatic compounds are frequently inexpensive precursors of a number of valuable organic substances. For example, vanillin is an important precursor chemical of 3,4,5-trimethoxybenzaldehyde, a chemical of well known importance to the pharmaceutical industry. However, known processes for the conversion of vanillin to trimethoxybenzaldehyde have certain drawbacks. U.S. Pat. No. 3,855,306 describes one such process in which vanillin is brominated to produce 5-bromovanillin using bromine and a concentrated hydrobromic acid solvent. The resulting 5-bromovanillin is then isolated from the reaction mixture and hydrolyzed to the corresponding hydroxyvanillin with sodium hydroxide and a copper catalyst. The resulting reaction mixture includes sodium bromide which is normally not recycled but rather is discarded or used elsewhere. Moreover, bromine and hydrobromic acid are both highly corrosive and hazardous to handle.

Other halogenated vanillin derivatives include 5-chlorovanillin and 5-iodovanillin. It is known however that chlorovanillin is unreactive toward hydroxide ion/copper and yields no hydroxyvanillin using conditions even more drastic than those effective for converting 5-bromovanillin to 5-hydroxyvanillin. Aryl iodides, on the other hand, are known to be more reactive than the corresponding bromocompounds in this kind of reaction. Iodine, however, would be prohibitively expensive if discarded as the bromine is in the above described bromination reaction. Reference to the iodination of vanillin to 5-iodovanillin may be found in H. Erdman, Svensk. Kem. Tids., 47, 223 (1935) Chem. Abstr. 30:449. Conversion of 5-iodovanillin to 5-hydroxyvanillin is disclosed in S. Banerjee, M. Manolopoulo and J. M. Pepper, Canadian Journal of Chemistry, 40, 2175 (1962). Post 403132 (Rhodium: "5-Hydroxyvanillin from 5-Iodovanillin", Novel Discourse) However, the processes there disclosed isolate the intermediate iodovanillin before hydrolysis and do not recover the by-product iodide ion from the various reactions.

A process has now been discovered from the conversion of armoatic compounds to hydroxy aromatic compounds which does not isolate an intermediate haloaromatic compound and which permits economical recovery and reuse of halide by-products produced during the reaction. The process involves the hydroxylation of an aromatic compound by reacting the aromatic compound in the presence of an aqueous solvent with a triiodide salt to form a reaction mixture containing the corresponding iodoaromatic compound, reacting the mixture, without separation of the iodoaromatic compound with a hydroxylating agent to form the corresponding hydroxy aromatic compound and additional iodide salt, separating the hydroxy aromatic compound from the iodide salt and recapturing the iodide salt. The corresponding alkoxy aromatic compound may be produced by alkylation of the hydroxy aromatic compound by known alkylation procedures.

The process of the invention renders cost-effective an otherwise cost-ineffective process using the iodination route. In the case of such processes as the conversion of vanillin to trimethoxybenzaldehyde, the process becomes basically a one-step or "one-pot" process by eliminating the purification of the intermediate 5-iodovanillin. Iodination of vanillin and conversion of the resulting iodovanillin to hydroxyvanillin may be carried out in the same reaction vessel. Moreover, efficient recycle of the by-product iodide salt to the triiodide reagent used in the reaction obviates the need to dispose of the valuable iodine/iodide material. Prior art processes necessarily separated and recovered the bromide or iodide by-product from the halogenation reaction and again from the hydroxylation reaction. In the present process, the iodide salt is recovered only after hydroxylation, at which time it may be oxidized to iodine and the iodine partially reduced to form the starting triiodide reactant. (The triiodide reagent is a solution of iodine in an excess of the iodide salt, e.g., NaI+I.sub.2 or NaI.sub.3). If chlorine is used as the oxidizing agent, the only net by-product of the reaction is sodium chloride, an obviously inexpensive waste by-product.

The starting materials useful in the practice of the invention are aromatic compounds subject to electrophilic substitution reactions. Such compounds may include benzene but the process is particularly suitable for aromatic compounds containing electron donating nuclear substituents, i.e. mono- or polycyclic aromatic compounds containing one or more hydrocarbon substituents such as an alkyl, cycloalkyl, aryl or aralkyl group and/or one or more hydroxy groups or aldehyde, acid, ester or ether radicals, i.e., alkoxy, carboxy, carboxyl or aldehyde carbonyl groups. The process is not useful with substituents such as poly-nitro, or ketone groups with an alpha hydrogen, which either react with the reagent or strongly de-activate the ring. Ketone groups are deactivating, as are aldehyde groups, but ketones containing an alpha hydrogen would react with the iodinating agent whereas the aldehydes would not. For example, diaryl ketones would not interfere. Only in the case of severely de-activating groups, such as poly-nitro groups, is the de-activation a problem in carrying out the iodination. Weakly de-activating groups such as aldehyde groups do not interfere with iodination. Useful aromatic compounds are simple monohydric phenols such as phenol, o-, m- and p-cresol and guaiacol; polyhydric phenols such as catechol and resorcinol; phenolic aldehydes such as protocatechualdehyde, vanillin, syringaldehyde, p-hydroxybenzaldehyde and 5-formylvanillin; phenolic acids such as vanillic acid, syringic acid, protocatechuic acid and p-hydroxybenzoic acid. The preferred aromatic reactants are those having at least one phenolic hydroxyl functionality.

The first step of the reaction involves iodination of the aromatic compound with the triiodide salt in the presence of water as a solvent. The water should contain from 0.7 to 1.25 molar equivalents of a hydroxide, preferably an alkali metal hydroxide, and from 1-2 molar equivalents of an alkali metal triiodide (e.g. iodine plus sodium iodide). The aqueous solvent should also contain from 0.1 to 20 mole % of an acid catalyst, which may be a mineral acid such as sulfuric, hydrochloric or phosphoric acid. Reaction is carried out at temperatures ranging from 20.degree.-120.degree. C. If the starting compound contains a nuclear substituent, iodination will occur in the ortho or para position on the nuclear ring.

The subsequent step of the reaction, hydroxylation, is carried out directly with the reaction mixture from iodination without any intermediate isolation or other processing of the reactants or by-products. A base, such as an alkali metal hydroxide or a quaternary amine such as tetraalkylammonium hydroxide, is added directly to the reaction mixture to make a final concentration of 0.5 to 6 molar, with 0.1 to 20 mole % copper metal, or cuprous salts such as oxide, chloride or iodide, at temperatures of from 50.degree.-120.degree. C. The preferred conditions are addition of sodium hydroxide to the iodination reaction mixture to give a concentration of 2-5 molar, then addition of 1-5 mole % copper dust, cuprous oxide or cuprous chloride, then allowing reaction at reflux (100.degree.-120.degree. C.) for about 18 hours.

The sodium or other iodide ion by-product may be recovered by neutralizing the caustic in the reaction mixture with an acid such as sulfuric or hydrochloric, extracting the organic product from the water solvent and then treating the water solution with an oxidizing agent. The oxidizing agent may be chlorine, sodium hypochlorite, hydrogen peroxide, persulfate, perborate or electrochemical oxidation may be used. The iodine which precipitates is then recovered from the water solvent by filtration, solvent extraction or distillation/sublimation. The temperature of the water phase may be from 0.degree. to 100.degree. C. The preferred method for iodine recovery is treatment of the water solution with sulfuric acid to neutralize the base, extraction of the hydroxy aromatic compound with organic solvents such as methylene chloride or toluene, oxidation with chlorine or electrochemically and filtration or solvent extraction to recover the iodine. The crude hydroxy aromatic compound may then be used directly in any subsequent alkylation procedure.

A specific description of a preferred practice of the invention with vanillin as the aromatic compound is as follows. Vanillin is dissolved in water with one molar equivalent of sodium hydroxide while the solution is warmed to 50.degree.-100.degree. C. One molar equivalent of iodine and two molar equivalents of sodium iodide are added to water to prepare one molar equivalent of NaI.sub.3.NaI. This sodium triiodide solution is added to the sodium vanillate solution along with a catalytic amount of sulfuric acid--preferably from 5 to 10 mole %. The mixture is stirred about one hour at a temperature of 50.degree.-100.degree. C., then sodium hydroxide is added to make the solution alkaline (from 1 to 5N). The copper catalyst is then added and the mixture heated at reflux until the iodovanillin is consumed, about 12 hours. The excess hydroxide is then neutralized and the 5-hydroxyvanillin extracted with a water-immiscible organic solvent. The aqueous phase bearing the sodium iodide is then subjected to oxidizing conditions and the resultant iodine precipitates from solution. The solid element is filtered out, and a sodium triiodide solution prepared by reducing a portion of the iodine to sodium iodide and dissolving the iodine in the iodide to make the sodium triiodide solution.

Alkylation of the hydroxy aromatic compound to the corresponding alkoxy aromatic compound may be performed in accordance with known alkylation procedures in which the hydroxy aromatic compound is reacted with an alkyl sulfate, alkyl halide or alkyl sulfonate in a suitable solvent, usually water, containing a base such as sodium hydroxide. Such reactions are shown at various places in the literature, as for ex. in Organic Synthesis, Col. Vol. II, page 619, 1943, in which veratraldehyde is prepared from vanillin. The iodide salt may, if desired, be recaptured subsequent to the alkylation reaction.

The following examples illustrate the practice of the invention. Unless otherwise indicated, all parts and percentages are by weight.

EXAMPLE 1

Vanillin (28.4 g, 200 mmole (millimole)) was dissolved in 1N NaOH (200 ml) and warmed to 90.degree. C. to avoid precipitation of sodium vanillate. A 2 molar aqueous solution of NaI.sub.3.NaI (105 ml, 210 mmole I.sub.2) plus 3.55 molar aqueous H.sub.2 SO.sub.4 (5 ml) was added over 3 hours with stirring. The iodine color was discharged, and a pale tan stirrable precipitate formed. The solution was then cooled to room temperature, acidified to pH 2-3 with 20% aqueous H.sub.2 SO.sub.4, and extracted with 10% methanol/90% chloroform. The organic phase was dried (MgSO.sub.4) and the solvent stripped to yield 53 g (99%) of 5-iodovanillin, more than 95% pure as analyzed by nuclear magnetic resonance spectroscopy (NMR).

EXAMPLE 2

Vanillin (3.04 g., 20 mmole) was dissolved in 1N sodium hydroxide solution (20 ml), and warmed to 80.degree. C. Then a solution of NaI.sub.3.NaI (2N) in water (10.1 ml) plus 20% aqueous H.sub.2 SO.sub.4 (0.5 ml) was added dropwise over 30 minutes, and the mixture stirred an additional 30 minutes. Sodium hydroxide (7.6 ml of 50% solution), and copper dust (128 mg=10 mole %) were then added and the mixture heated at reflux overnight. The solution was cooled, filtered to recover catalyst, neutralized with 20% aqueous H.sub.2 SO.sub.4, and extracted thoroughly with chloroform. The organic base was dried (Na.sub.2 SO.sub.4) and stripped to yield 3.1 g (99%) of organic material consisting of 75% 5-hydroxyvanillin and 25% vanillin.

The aqueous phase was concentrated under vacuum, and treated with the theoretical quantity of chlorine as a water solution. The purple iodine crystals were removed by filtration. As 87% recover of iodine was achieved.

EXAMPLE 3

Vanillin (2.84 g, 20 mmole) was dissolved in 1N NaOH (20 ml) at 80.degree. C., then a mixture of 2N (NaI.sub.3.NaI)/H.sub.2 O (10.1 ml=20.2 mmole I.sub.2) plus 20% aqueous H.sub.2 SO.sub.4 (0.5 ml=8 mole %) was added dropwise over 30 minutes. A tan precipitate formed. The reaction mixture was stirred an additional 3.5 hours. A 10% solution of Na.sub.2 S.sub.2 O.sub.3 (1.5 ml) was added to reduce excess iodine, then 50% aqueous NaOH (7.6 ml) was added (to make 4N in NaOH), plus copper dust (128 mg, 2 mmole, 10 mole %) added. The mixture was refluxed overnight, cooled to room temperature, filtered to remove catalyst, the pH was adjusted to 2 with 20% aqueous H.sub.2 SO.sub.4, and the solution extracted 5X with 20% methanol/80% chloroform. A yield of 3.1 g (99%) of product was obtained, which NMR showed to consist of about 75% 5-hydroxyvanillin and 25% vanillin.

Example 3 was repeated using concentrations of NaOH base ranging from 1N to 6N, using KOH and LiOH in place of NaOH as the base for the iodination procedure. All gave substantially equivalent results.

Example 3 was also repeated using from 5 to 10 mole % of cuprous oxide, cuprous chloride, cuprous iodide and copper dust, as the catalyst for conversion of the iodovanillin to hydroxyvanillin. Recovery of 5-hydroxyvanillin was 80-85% (remainder vanillin) with copper dust, from 70-80% with the copper oxide or salts.

EXAMPLE 4

Vanillin (20 mmole) was iodinated and converted to 5-hydroxyvanillin as set forth in Examples 1-3. The aqueous phase from the extraction of 5-hydroxyvanillin (theoretically containing 80.8 mmole NaI) was then concentrated in vacuum to remove dissolved volatile organics, then chlorine water [42 mmole Cl.sub.2 =500 ml of 0.086M (0.61%) chlorine water] was added slowly. The iodine precipitate was filtered off and washed with water. To determine the quantity recovered, the iodine was washed off the filter with 2N sodium iodide solution (300 ml), and then titrated (at pH 5) with 0.2N sodium thiosulfate solution until the iodine color disappeared. A quantity of 350 ml of the 0.2N thiosulfate was consumed showing that 70 mmole I.sub.2 was recovered, an efficiency of 87%.

The process thus provides an essentially one-step process for the nearly quantitative conversion of aromatic compounds to hydroxy aromatic compounds and for the recovery and recycle of the reagent used for conversion.
 
 
 
 
    Antibody2
( )
07-25-01 21:28
No 198892
      Re: Iodination of Vanillin     

whistle hot damn, way to go Zygoat! written so that even idiots like me can decipher it. I wonder if DCM can be substituted for chlorofrom in the extraction?

asides from the obvious, the other thing that strikes antibody is the absence of an inert atmosphere requirement for the 2nd step.


"All those memories lost like rain..."
 
 
 
 
    foxy2
(Hive Addict)
07-26-01 03:38
No 198956
      Re: Iodination of Vanillin     

That is beautiful, looks like you struck honey!
This really eliminates the need to mess with lignin,
sorry halfapint.  Well as i read further it appears to dissolve.

One thing seems a little unclear to me.  Do they just leave solid I2 in the bottom to be consumed in the reaction?  Or does it form the triiodide and completely dissolve?  I'll bet this procedure would work with potassium iodide to.

I would love to hear a report from someone's trial run of this procedure.  I'll bet there are more than a few bee's who have these reagents laying around their private hive.
smile

In the article I posted they may have used the KICl2 to try to sidstep this very patent.  Nobody wants to pay royalties.


Do Your Part To Win The War
 
 
 
 
    foxy2
(Hive Addict)
07-26-01 20:39
No 199100
      Re: Iodination of Vanillin     

Well I found the info for the route I posted.  It makes this method a little easier than the Triiodide method because iodine is being watched ever increasingly due to the meth makers.  Sorry for some reason the plus sign would not show up in this post.

Potassium Dichloroiodide (KICl2)

I. Dry Method

       KIBr2 (plus) Cl2 = KICl2 (plus) Br2

  Dry Cl2 is allowed to react with dry KIBr2 at room temperature.  After a few minutes KICl2 is formed and the Br2 produced is carried off in the Cl2 stream. (When the reaction is continued for a longer period, KICl4 is formed instead.)

  It is also possible to prepare KICl2 in a dry process by grinding KICl4 with KIBr2 and driving off the Br2 as its formed.


II. Aqueous Process (This is the paydirt here)

       KI (plus) Cl2 = KICl2

   Chlorine is introduced into a very concentrated solution of KI until the initially precipitated I2 redissolves.  In order to prevent further chlorination to KICl4, finely pulverized KI is added until the I2 that separates is redissolved - with slight heating if necessary.  Crystallization occurs on cooling.

Properties:
   Long, orange crystals, very unstable in air.  Begins to soften at 60°C in a sealed tube; liberates labile halogen at 215°C.

References:
I.  H.W. Cremer and D.R. Duncan.  J. Chem. Soc. (London)  1931, 1863.
II.  F. Ephram.  Ber. dtsch. chem. Ges. 50, 1086 (1917).



Do Your Part To Win The War
 
 
 
 
    foxy2
(Hive Addict)
07-26-01 20:54
No 199105
      Re: Iodination of Vanillin     

Potassium DibromoIodide  (KIBr2)

   KI + Br2 = KIBr2

   Since KIBr2 crystallized from aqueous solution always contains water of crystallization, it must be prepared in a dry process.

   A given quantity of finely pulverized and dried KI is mixed with an equal quantity (by weight) of Br2 and the mixture allowed to stand in a sealed flask for three days.  When the reaction ends, the product is freed from excess Br2 by placing the unstoppered flask in a dessicator over I2 or NaOH.

Properties:
   Shiny red crystals which melt at 58°C in a sealed tube, evolving labile halogen at 180°C

References:
H.W. Cremer and D.R. Duncan.  J. Chem. Soc. (London) 1931, 1857.
W.N. Rae.  J. Chem. Soc. (London) 107, 1290 (1915).

Do Your Part To Win The War
 
 
 
 
    foxy2
(Hive Addict)
07-26-01 21:29
No 199109
      Re: Iodination of Vanillin     

Potassium Triiodide  (KI3*H2O)

     KI + I2 + H2O = KI3*H2O

  The theoretical quantity of I2 is added to a hot saturated solution of KI; after the iodine dissolves, the mixture is cooled to 0°C, whereupon KI3*H2O crystallizes out.

Properties:
  Dark brown, hygroscopic prisims which melt in a sealed tube at 38°C and liberate iodine at 225°C, leaving KI.  Anhydrous KI3 is unstable at room temperature while the monohydrate is stable, see ref II.

References:
I.  H.L. Wells and H.L. Wheeler.  Z. anorg. allg. Chem. 1, 453 (1892).
II. N.S. Grace.  J. Chem. Soc. (London) 1931, 608.
    H.W. Foote and W.C. Chalker.  J. Amer. Chem. Soc. 39, 565 (1908).


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    foxy2
(Hive Addict)
07-26-01 21:42
No 199114
      Iodination of Sassy Possibilities     

I wonder how these various iodinating reagents would act in the prescence of safrole?  Halogens add to alkenes much easier than the add to aromatic rings, right? Could there be an easy route to iodosafrole lurking in these compounds?
It seems like an area ripe for research.
I wish i was a chem professor with a nice NMR/IR to look at the products of said trials.
cool

Also it seems highly probable that these methods would apply to makeing 2C-I, iodinate the benzaldehyde and proceed from there.


Do Your Part To Win The War
 
 
 
 
    moo
(Newbee)
07-27-01 03:56
No 199190
      Re: Iodination of Sassy Possibilities     

Let's not forget the possibility of going from 2,5-DMB to 4-OH-2,5-DMB for TMA-2 and MEM.

understanding is everything
 
 
 
 
    Rhodium
(Chief Bee)
07-27-01 07:29
No 199214
      Re: Iodination of Sassy Possibilities     

The patent is now up with pictures at ../rhodium/chemistry /iodovanillin.html

../rhodium/chemistry
 
 
 
 
    Antoncho
(Official Hive Translator)
07-27-01 14:03
No 199293
      What about separation?     

Hello everybody.

Having carefully read this masterpiece i noticed that one thing in the patent still remained unclear: how do you separate the mxtr of dihydroxy- and vanillin with which you're left at the end?

smilelaughsmileI think Half-a-Pint won't be very eager to find a separation procedure in this case.

I would think that since dihydroxymethoxyBA is much more hydrofillic than vanilline, we could use about the same procedure as in the separation of V. from p-hydroxyBA (see lignin syringaldehyde thread for details).

Well, even if it doesn't work you always can get yor ald's mixtr back and even, if no other ideas visit yor mind, alkylate it as is to get your final product w/some inactive impurity (i wonder though if 3,4-DMPA might have any potentiating effect like, say, 2C-D)

Any ideas visiting your minds, oh my dear friends?
 
 
 
 
    Rhodium
(Chief Bee)
02-05-04 17:08
No 486593
      5-Iodovanillin and 5-Iodoveratraldehyde
(Rated as: good read)
    

As mentioned in Post 198873 (ZyGoat: "Re: Iodination of Vanillin", Chemistry Discourse):

Phenoldehydrierungen IV. Dehydrierende Kupplung einiger Guajakolderivate.
Holger Erdtman
Sv. Kem. Tidskr. 47, 223-230 (1935) (../rhodium/pdf /iodo-vanillin-veratraldehyde.pdf)

Summary:
5-Iodovanillin is prepared by dissolving vanillin in dilute sodium hydroxide and to that a solution of KI3 (iodine tincture?) is added dropwise. When the reaction is over, excess iodine is reduced with bisulfite, the precipitate filtered and recrystallized from GAA to give colorless prisms of 5-iodovanillin in 95% yield, mp 181.5°C.

5-Iodoveratraldehyde is prepared by treating a well-stirred suspension of 5-iodovanillin in ethanol with 3-4x molar excess of dimethyl sulfate, and an equimolar amount of 40% NaOH is then added dropwise, with cooling, if needed. The product, which first oils out, is recrystallized from aqueous methanol or aqueous acetic acid, mp 73-74°C.

The Hive - Clandestine Chemists Without Borders
 
 
 
 
    Grimble_Gromble
(Stranger)
03-15-04 17:55
No 495307
      2C-I using NaI+I2     

Could I make 2C-I from 2C-H without problems in this way? I read in another tread the 2C-I is maked using silver as catalyst.

Look at the sky... Look at the river... Isn´t it good?
 
 
 
 
    Nicodem
(Hive Bee)
03-15-04 18:27
No 495311
      The amines easily form haloamines in basic...     

The amines easily form haloamines in basic conditions. So I think the answer to your qustion is no.

“The real drug-problem is that we need more and better drugs.” – J. Ott
 
 
 
 
    moo
(Hive Bee)
03-15-04 23:28
No 495357
      I think only phenols can be iodinated that...     

I think only phenols can be iodinated that way.

fear fear hate hate
 
 
 
 
    Mountain_Girl
(Hive Bee)
05-04-04 12:11
No 504754
      KI or I2 ?     

Rhodium's post :

5-Iodovanillin is prepared by dissolving vanillin in dilute sodium hydroxide and to that a solution of KI3 (iodine tincture?) is added dropwise. When the reaction is over, excess iodine is reduced with bisulfite, the precipitate filtered and recrystallized from GAA to give colorless prisms of 5-iodovanillin in 95% yield, mp 181.5°C.




I'm a bit confused cos the original text says:

"3.04 g Vanillin werden in 10 cc 0.2 n Natronlauge gelost, hierauf wird mit Wasser auf 25 cc verdunt.
5.08 g Jod werden dann in 50 cc Wasser durch Zusatz der notigen Menge Kaliumjodid gelost und diese Losung unter Ruhren langsam zu der Vanillinnatriumlosung gegeben. Das Jod entfarbt sich schnell und gegen Ende der Reaktion fallt ein Brei von 5-Jodvanillin aus."

My german is extremely basic but does this mean 'dissolve 5.08 g Pottasium Iodide in 50 cc water and add to the Sodium Vanillate solution' ?
Why do they refer to '5.08 g Jod' ?


Mountain Boy
 
 
 
 
    hypo
(Hive Addict)
05-04-04 17:17
No 504786
      no     

"5.08g iodine are dissolved in 50ml water by adding the needed amount of KI
and this solution is slowly added to the Na-vanillate solution".

hth

http://www.animalyawns.com
 
 
 
 
    Mountain_Girl
(Hive Bee)
06-26-04 15:45
No 515542
      Iodovanillin from tincture..but not too much     

Ah thanks Hypo.

Wuz wondering..
tincture is expensive & comes in a fixed concentration of 2.5 % KI, 2.5% I2 (in my case),
KI is required to dissolve the I2,
would it be feasible to add to the Na vanillate soln your tincture,
then as the dissolved I2 reacts (the 2.5% originally present),
solid I2 is added to the mixture (recovered from tincture naturally) at the same rate that it is used up so that there is always enough KI to dissolve all of it (i.e. maintain less than or equal to about 2.5% I2) until all the required I2 is added...

Hmmm..hope I has made a sensible question...wine is fucking with me receptors and my reception so its hard to tell

Mountain Boy