Sciencemadness Discussion Board - Kolbe reaction

Kolbe reaction

KABOOOM(pyrojustforfun) - 30-10-2003 at 20:50

it's a way of preparing saturated/unsaturated hydrocarbons via electrolysis of aliphatic carboxilic acid alkali metal salts. eg : 2CH3COO- <s>   ></s> H3C-CH3 +2CO2 -OOC-CH2CH2-COO-</s up> <s>   ></s> H2C=CH2 + 2CO2 succinic acid the above definition and examples come from The penguin dictionary of chemistry (translated it back to its original language) now just think about the endless possible reactions ... trichloroacetic acid to hexachloroethane, nitroacetic acid to dinitroethane, trinitroacetic acid to hexanitroethane, glycine to ethylene diamine, serine to 1,2-di(hydroxymethyl)ethylene diamine, glyoxylic acid to glyoxal, glyceric acid to erythritol, gluconic acid to 1,2,3,4,5,6,7,8-octahydroxyoctane, lactic acid to 2,3-dihydroxybutane, acrylic acid to butadiene, methacrylic acid to 2,3-dimethylbutadiene, maleic acid to acetylene or acetaldehyde, oxime of mesoxalic acid to fulminic acid, pyruvic acid to imethylglyoxal, .......
Edit: corrected a typo (changed dimethylglyoxime to dimethylglyoxal)

[Edited on 20-11-2003 by KABOOOM(pyrojustforfun)]

Theoretic - 17-11-2003 at 05:56

Hmmm... Sounds nice! Under what conditions does this work?

KABOOOM(pyrojustforfun) - 18-11-2003 at 21:53

US 2,760,926 describes hydrocarbon aliphatic ethers prepared by electrolysis of salts of aliphatic carboxylic acids under anhydrous or substantially anhydrous conditions

from US 5,423,454 US5423454 Method of propellant gas generation (electrochemically) :
<blockquote>quote:<hr>In a variation of the Kolbe reaction, a mixture of propionic acid and potassium propionate ,may be electrolytically reacted to form 63 mole percent carbon dioxide, 15 mole percent butane, 14 mole percent ethane and 6 mole percent ethylene for almost 98% gaseous product yield. Since the major product is still carbon dioxide, the flammability of the other gaseous products is suppressed by its presence, with all of the gaseous products functioning as propellant.

In another variation of the Kolbe reaction, the use of dicarboxylic acids, dicarboxylic acid salts, hydroxy acids and hydroxy acid salts with suitable ancillary agents, as subsequently described, can yield 2 or 3 molecules of carbon dioxide per electron transfer. Such systems are desirable when rapid gas regeneration is required.

Conducting the Kolbe type reaction in a mixture of methanol and water improves efficiency over water alone. The efficiency of the reaction may be further improved through the presence of foreign anions such as bicarbonate, dihydrogen phosphate, fluoride and sometimes sulfate. These anions may be furnished as alkali or alkaline earth metal salts of sodium, potassium, calcium and barium. Such cations have not been found to have a significant deleterious effect. The system should, however, be essentially free of cations of cobalt, copper, iron, lead and manganese since even low concentrations of these metals have a deleterious effect.

Aromatic acids and aromatic acid salts, such as benzoic acid and benzyl acetate may be utilized in Kolbe type reactions. In general, however, it is desirable to avoid such aromatics in reaction mechanisms where aromatics such as benzene are generated.

For aerosol applications using the Kolbe reaction, it is desirable that the minimum electrical potential for activation, i.e., the lowest voltage at which the desired reactions begin, be between 2.1 and 3.0 volts. The current density is usually from 0.15 to 3 amperes per cm.sup.2 and preferably the current density is in the area of 0.25 ampere per cm2 <hr></blockquote>
<blockquote>quote:<hr>... If chemistry based upon the Kolbe reaction is used, an 8-ounce container will require an electron transfer of about 2,470 coulombs or 0.69 ampere-hours at a minimum of 3 volts, to effect total dispensing of the product ...<hr></blockquote>
<blockquote>quote:<hr>EXAMPLE I
An electrolytic cell is made using an electrolyte comprising 60 ml of 5N aqueous acetic acid containing 5 grams of potassium acetate gelled with methyl cellulose...
...The current density through the electrolyte using platinum electrodes of 0.4 amperes per cm.sup.2 which yields 2.5 mole percent methane, 6.4 mole percent ethane and 91 mole percent carbon dioxide. The reaction produces almost 100% gas. Current efficiency is found to be 82 percent when graphite electrodes are used.<hr></blockquote>

<a href="http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search-bool.html&r=18&f=G&l=50&am p;co1=AND&d=ptxt&s1='kolbe+reaction'&OS="kolbe+reaction"&RS="kolbe+reaction"">US 5,811,627 Alkylation reactions</a>:
<blockquote>quote:<hr>The Kolbe Reaction is a well known electrochemical reaction that involves an oxidation at an anode of the carboxylate ion of an organic acid to produce either a free radical or a carbonium ion depending upon the electrode used and the voltage applied. These reactions are as follows:
<img src="http://www.angelfire.com/rnb/pjff/Pat.gif">
where R is either a hydrogen or a saturated or unsaturated hydrocarbyl material, that can include, esters, amines, amides, ketones, etc. When a carbon electrode is used instead of platinum, there is a tendency to remove two electrons at the anode, thereby generating a carbonium ion shown in equation 9. When precious metal anodes such as platinum, tin, gold, silver, or palladium, are used, the more usual course of the reaction is to generate the free radical shown in equation 8. This radical can and often does couple with itself in a bi-radical coupling reaction in accordance with equation 10. <hr></blockquote>
<blockquote>quote:<hr>In Topics in Current Chemistry, vol. 152, pages 92-151, the addition of Kolbe Radicals to double bonds was discussed. Reference was made to the work of Louis Schmerling and James P. West reported in the Journal of the American Chemical Society, vol. 71, 2015-2019 (1949). The conclusions reached are provided on page 142 of volume 71. Among these conclusions were: (a) due to the high concentration of radicals in the reaction layer in front of the electrode, termination and not propagation predominates even in the presence of alkenes; (b) in the presence of high current, dimers are favored; (c) elevated pressures favor Kolbe Coupling; (c) high temperatures favor disproportionation; (d) high current favored formation of additive monomers and low current favored additive dimers; (e) in the presence of reactive olefins such as butadiene, isoprene, or styrene good yields of adduct were observed; (f) foreign cations ranging from most to least effective in producing lower yields are Fe+2 < Co+2 < Ca+2 < Mn+2 < Pb+2 and alkali metals, alkaline rare earth metals, alkylammonium ions, zinc, or nickel ions do not seem to affect or influence Kolbe Reactions.<hr></blockquote>
reference:<blockquote>quote:<hr>Details as to the best procedure for carrying out a Kolbe-like reaction are disclosed in Advances in Organic Chemistry: Methods and Results, Published by lnterscience Publishers, Vol. 1, beginning on page 5 (QD 251.A36).<hr></blockquote>
<a href="http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search-bool.html&r=17&f=G&l=50&am p;co1=AND&d=ptxt&s1='kolbe+reaction'&OS="kolbe+reaction"&RS="kolbe+reaction"">US 5,841,002 Process for the commercial production of polyhydroxy alcohols and glycols</a> :
<blockquote>quote:<hr>The Kolbe reaction was first carried out in 1849 and has been used since in organic synthesis. Among the simplest materials to undergo the Kolbe reaction when electrolysed are carboxyllc acids. An acid of general formula RCOOH where R is a hydrogen atom, an alkyl group or an aryl group will reversibly dissociate to yield hydrogen ions and ions of formula RCOO- . Generally the Kolbe reaction is carried out in the presence of sodium or potassium carboxylate salts because many carboxylic acids are only weakly ionised and are therefore poor conductors of electricity. These anions will, on electrolysis under suitable conditions, lose an electron to form free radicals of formula RCOO. . These radicals are unstable and undergo decarboxylation to form R. and CO2, thereby liberating carbon dioxide at the anode. Two R. radicals can unite to yield a compound of formula R--R. Other compounds may also be synthesised under the Kolbe reaction conditions. For example, in aqueous solution OH- ions will be present and on discharge will form HO. radicals which can combine with R. radicals to produce alcohols of formula R--OH. The hydroxyl radicals can also participate in the oxidation of the organic compounds via hydrogen abstraction reactions, addition to double bonds, and combination with organic radicals. Reactions of this type are believed to be responsible for the removal of heavy but non-ionisable materials in the anode region. The reaction
2HO. <s>   ></s> H2O2 <s>   ></s> H2O + 1/2O2( 20)

is believed to be at least partially responsible for the formation of oxygen in the anode region.

Esters formed by the joining of R. and RCOO.sup.., i.e. RCOOR, hydrocarbons of formula RH, and olefins of formula containing one less hydrogen atom than R. are also products under the Kolbe reaction conditions. Peroxy compounds of the formula HOOH, ROOH or ROOR may also be formed by free radical combination under certain conditions.

In an electrolytic cell with anode and cathode regions the free carboxylic acid can be formed by the transfer of alkali metal ions through a membrane dividing the regions. ##STR14##

The application of the Kolbe reaction and of other reactions which can occur under the Kolbe reaction conditions in organic synthesis has been extensively reported and reviewed, for example in:

1) Svadkovskaya, G. E. and Voitkevich, S. A., "Electrolytic Condensation of Carboxylic Acids" in Russian Chemical Reviews, 29(3), 1960, pages 161 to 167;

2) Koehl, W. J., "Anodic Oxidation of Aliphatic Acids at Carbon Anodes" in Journal of the American Chemical Society, 1964, pages 4686 to 4690; and

3) Eberson, Lennart, "The Chemistry of Carboxylic Acids", Interscience, 1969, pages 54 to 99.

According to the afore-mentioned article by Svadkovskaya, G. E. and Voitkevich, S. A., the anode material has an effect on the course of the reaction in the electrolysis cell. Thus it was reported that in the electrolysis of acetates the highest yields of ethane were obtained using a smooth platinum or iridium anode, while gold, nickel and platinised platinum anodes gave negative results. On the other hand graphite anodes gave moderate yields of ethane.

In the process of the invention it is accordingly preferred to use an anode made of a material that promotes the Kolbe reaction. Thus it is preferred to use smooth platinum or iridium anodes. Conveniently the cathodes are also smooth platinum electrodes.

The Kolbe reaction is not limited to carboxylic acids. Alkali metal carboxylates will also undergo electrolytic decomposition according to the mechanism outlined briefly above and reported fully in the literature. Generally the Kolbe reaction is carried out in aqueous solution containing free carboxylic acid and the corresponding alkali metal salt of the acid. <hr></blockquote>
I found more but I'm in a hurry.. maybe tomorrow

KABOOOM(pyrojustforfun) - 27-11-2003 at 22:58

from <a target=blank href="http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=2&u=/netahtml/search-bool.html&r=51&f=G&l=50&am p;co1=AND&d=ptxt&s1='kolbe+reaction'&OS="kolbe+reaction"&RS="kolbe+reaction"">US 4,097,344 Electrochemical coupling of perfluoroalkyl iodides</a>:<blockquote>quote:<hr>Electrolysis is conveniently carried out at a specified constant current density, achieved by application of an anode potential above the cricical potential at which the Kolbe reaction starts, generally in the range of 2.1-2.8 volts (normal hydrogen electrode)<hr></blockquote>
from <a href="http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=2&u=/netahtml/search-bool.html&r=57&f=G&l=50&am p;co1=AND&d=ptxt&s1='kolbe+reaction'&OS="kolbe+reaction"&RS="kolbe+reaction"">US 3,992,435 Process for electrolytic synthesis of polyalkylbiphenylpolycarboxylic acid compounds</a>:<blockquote>quote:<hr>...It is equally well known that aromatic carboxylic acids in which the carboxyl group is directly attached to a benzene ring fail to undergo the Kolbe reaction to any extent, as is reported by B. C. L. Weedon ("Anodic Syntheses With Carboxylic Acids" Quarterly Reviews Vol. 6, No. 4, 1952 p. 387-388). Benzoic acid on electrolysis in methanol yields benzene rather than undergoing a coupling reaction<hr></blockquote>
I linked to patents just to show where I extracted them from. it's not necessary to read them all. the quotes give some info on condition in which the kolbe reaction takes place.

nightshade - 27-5-2008 at 09:17

what about amino acids?

MagicJigPipe - 27-5-2008 at 11:05

Quote:

In general, however, it is desirable to avoid such aromatics in reaction mechanisms where aromatics such as benzene are generated.

Why? It seems to me that benzene would be desirable. Perhaps this could be a possible new route to benzene production?

Now that they said that, I am very fascinated with this. I mean, most of us should have no use for actually preparing a mixture of methane and ethane since this is basically natural gas but, products such as ethylene, propylene and benzene are VERY interesting!

I'm going to do some research on this reaction. I'll be back.

[Edited on 5-27-2008 by MagicJigPipe]

indigofuzzy - 7-6-2008 at 07:10

Quote:

I mean, most of us should have no use for actually preparing a mixture of methane and ethane since this is basically natural gas

unless you're obsessed with green fuel...... make natural gas from vinegar, and skip the fossil fuels.

Hypothetically: could this reaction (with proper reagents) produce a soup of hydrocarbons similar to gasoline?

12AX7 - 7-6-2008 at 09:24

By the sound of it, you'll get gasoline if you process pentanoic and hexanoic acids (yielding C8-10 straight chains).

Tim

MagicJigPipe - 7-6-2008 at 13:21

I'm still interested in the benzene that apparently is "undesirable". I still don't understand why the hell one would want to avoid making benzene. Weird.

Quote:

Benzoic acid on electrolysis in methanol yields benzene rather than undergoing a coupling reaction

Hell yes! I wonder what the yeilds would be? This seems like it might be a cheap and easy way to benzene even if the yields were 20%.

I am so going to try this once I receive my platinum electrode.

EDIT
I always thought gasoline was C5-C-12 with significant amounts of toluene, benzene, MTBE, trimethylbenzene and a small amount of naphthalene (and now up to 10% EtOH). I wonder if a "straight" mix of C5-C12 aliphatic hydrocarbons would cause problems in a standard gasoline engine because of the fairly large amounts of aromatic compounds in normal gasoline which they are designed to use.

[Edited on 6-7-2008 by MagicJigPipe]

12AX7 - 7-6-2008 at 14:26

100 octane is measured as 100% octane. I don't remember if that's straight chain or one of the particularly branched versions (tertiary hydrocarbons have higher octane as I recall).

Tim

MagicJigPipe - 7-6-2008 at 15:39

According to Wikipedia 100 octane would be pure iso-octane.

Quote:

Octane number is the number which gives the percentage, by volume, of iso-octane in a mixture of iso-octane and normal heptane, that would have the same anti-knocking capacity as the fuel which is under consideration. For example, gasoline with the same knocking characteristics as a mixture of 90% iso-octane and 10% heptane would have an octane rating of 90. [1]...

...References

1. ^ Page 992. Brown, Theodore, and LeMay, Eugene, et al. Chemistry: The Central Science. Ninth edition. Pearson Education Inc. Upper Saddle River, NJ. 2003. ISBN 0-13-066997-0.

[Edited on 6-7-2008 by MagicJigPipe]

not_important - 7-6-2008 at 16:58

yup - straight chain alkanes are rather bad fuel for Otto cycle engines, having a low octane rating, but good fuel for Diesel engines as they have decent to good cetane numbers. Aromatics in general have very good octane ratings, but the US and some other countries have limits on total aromatic content and tight limits on benzene levels. The alkanes are C4-C12, the exact range being determined by climate.

So to make decent gasoline you need to reform straight chain to branched chain. Conditions similar to those used in reforming will thermally decarboxylate fatty acids. The Kolbe reaction just isn't that energy efficient, I suspect the thermal-catalytic routes to that range of hydrocarbons are much more effective.

nightshade - 8-6-2008 at 11:30

so how could one make the kolbe work for amino acids and sodium acetate.

not_important - 8-6-2008 at 21:22

Quote:

Originally posted by nightshade
so how could one make the kolbe work for amino acids and sodium acetate.

You mean a mixed Kolbe? Doesn't work well when there is a amino, hydroxy, or alkoxy group alpha to the carboxylate carbon.

woelen - 9-6-2008 at 06:57

I have done quite some experimenting with the Kolbe reaction (and made a web page about it and a thread over here at sciencemadness) and it only seems to work well with unsubstituted acids. E.g. acetate gives ethane, propionate gives n-butane, etc. I did tests with chloroacetic acid, and that gives CO and CO2.

The reaction with succinic acid seems interesting though and that is something which I will try. This could be a nice route to ethene, a gas which otherwise is not easily prepared without some decent glassware and heating apparatus.

nightshade - 9-6-2008 at 09:16

Well I read somewhere it said that alpha acids can't bond little or no product is made.i down loaded chem guys notes,and even they say a alpha acid won't work.in another book i got it only even number carbon acids can be used.Amino acids are alpha amino acids are they not .

MagicJigPipe - 9-6-2008 at 14:18

So, has anyone tried benzoic acid? I'm surprised I am the only one that is anxious to see if this works considering the virtual unavailability of benzene in the US and the large setup cost of the sodium benzoate decarboxylation.

Ritter - 30-7-2008 at 06:49

Quote:

Originally posted by KABOOOM(pyrojustforfun)
it's a way of preparing saturated/unsaturated hydrocarbons via electrolysis of aliphatic carboxilic acid alkali metal salts. eg : 2CH3COO- <s>   ></s> H3C-CH3 +2CO2 -OOC-CH2CH2-COO-</s up> <s>   ></s> H2C=CH2 + 2CO2 succinic acid the above definition and examples come from The penguin dictionary of chemistry (translated it back to its original language) now just think about the endless possible reactions ... trichloroacetic acid to hexachloroethane, nitroacetic acid to dinitroethane, trinitroacetic acid to hexanitroethane, glycine to ethylene diamine, serine to 1,2-di(hydroxymethyl)ethylene diamine, glyoxylic acid to glyoxal, glyceric acid to erythritol, gluconic acid to 1,2,3,4,5,6,7,8-octahydroxyoctane, lactic acid to 2,3-dihydroxybutane, acrylic acid to butadiene, methacrylic acid to 2,3-dimethylbutadiene, maleic acid to acetylene or acetaldehyde, oxime of mesoxalic acid to fulminic acid, pyruvic acid to imethylglyoxal, .......
Edit: corrected a typo (changed dimethylglyoxime to dimethylglyoxal)

[Edited on 20-11-2003 by KABOOOM(pyrojustforfun)]

I have experience with the Kolbe elerctrolysis. One major limitation is decarboxylation of the acids. The other is the very corrosive effect on the Pt electrodes. And if you are using two different acids A & B, you will also get the coupling products A-A, B-B as well as A-B.

benzoic acid

Dr.3vil - 30-7-2008 at 08:41

From "electrochemistry oforganic compounds"
walther Lob
1906

Benzoic Acid.—Benzoic acid and its salts were examined
by several investigators, first by Matteuci,1 then by Brester,2
but most thoroughly by Bourgoin.3
The result of all these investigations is to show that here
no secondary reactions take place, as was observed in the case
of the fatty acids, but that the only effect of the current is to
produce a separation into hydrogen (or metal) and the acid
radical, the latter regenerating the acicl at the positive pole.
In an alkaline solution it is possible to so increase the oxida-
tion that the benzoic acid is destroyed. The decomposition prod-
ucts which then appear at the anode are carbon dioxide, carbon
monoxide, and sometimes acetylene. The odor of bitter
almonds is also frequently observed.
A thorough investigation was made by Lob,4 who employed
a current having a potential of 6-7 volts and a current density
of 15-20 amp. per sq. cm. and obtained a small quantity of

1 Bull. soc. chim. 10, 209 (1868).
2 Jahresb. f. Chem. (1866), 87.
3 Bull. soc. chim. 9, 431 (1867).
4 Ztschr. f. Elektrochemie, 2, 663; 3, 3 (1896).

a substance containing sodium, but the chemical nature of
which has not yet been determined. There is formed besides
this compound a small quantity of benzaldehyde; as well as
acetylene and carbon monoxide. Under no circumstances do
diphenyl or other hydrocarbons occur; nor do fatty acids
appear, which is otherwise generally the case in an extensive
oxidation of this character.
According to the investigations of Schall,1 diphenyl does,
however, occur if a solution of sodium benzoate in molten
benzoic acid is electrolyzed at 100 volts between silver elec-
trodes.

-EDIT-

since we are talking about electrons and uses for benzoic acid or its salt

how about benzoic acid to:

benzyl alcohol
benzaldehyde

see https://sciencemadness.org/talk/viewthread.php?tid=2223

Electrolytic Reduction of Aromatic Carboxylic Acids. I. Reduction of Benzoic Acid under Pressure

Shin-ichi Ono and Tsuneo Yamauchi
Bulletin of the Chemical Society of Japan , Vol. 25 (1952) No. 6 pp.404-407

[Edited on 30-7-2008 by Dr.3vil]

[Edited on 30-7-2008 by Dr.3vil]