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All 3 posts Subject: Oxalic and formic acid from sawdust Please login to post Down

ning
(Hive Bee)
11-05-03 16:29
No 468940
      Oxalic and formic acid from sawdust

please note, it was dark and early. ning was a little spun and worked up. If this post seems a little...crazy, well, that's because it is.

Refs and abstracts on oxalic acid production by fusion of alkali with cellulose-containing materials.

aka How to make even more precursors from wood, paper, and lye in your kitchen.

Who's got a Big Library of Third-World-Nation Scientific Journals? Maybe someone could get some of these papers? They are all pretty obscure. Perhaps the "developed world" has no use for such technology anymore? Guys, you can't get much more OTC than a cast iron skillet, some sawdust or shredded paper, and lye. And you can get more than 30% BY WEIGHT oxalic acid back! Forget that nasty nitric acid method, the alkali fusion method is just the mass production method for oxalic acid we've been waiting for. I needn't remind you that with large quantities of oxalic acid in hand, if a really deprived bee needed some glycerin, they could make that from cooking oil or lard…about 130 grams per kilo of oil saponified. I know, it's not a lot, but if you can't get it any other way…So if this whole dimethy oxalate methylation thing pans out, halfapint's dream of a "jungle synth" might not be so farfetched. From those two, formic acid, which can also be made into formamide with urea in high yield(Not going to tell you where to get that one…look down…), allyl alcohol, as well as the methanol and acetic acid if necessary, are all makeable from the most basic elements of the earth--fat, lye, urine, and wood. Let's see the DEA and its lubricious triletteral brethren try to control those! Squirm Wormy, Squirm!!! The war is lost! Wake up! It's just a matter of time!

Note, some of the abstracts mention up to 15% formic acid production by weight by changing reaction conditions. (lower temperature) From sawdust! Not as good as the oxalic acid yield, but still, Nice.
Also, most notably acetic acid may be present in very non-trivial amounts. With the availability of vinegar, it's kind of a non-issue, but some bees may have real use for such things. Got a ketene lamp? Waste not, want not…
The separation is the tricky part, but by using lime to convert the acids to their calcium salts, removing the oxalic acid is easy, because the other two acids' calcium salts are soluble in water (~200 g/L), while calcium oxalate is notoriously insoluble. (That's why kidney stones suck. Some plants use little crystals of calcium oxalate as needles to carry their poison through the skin. Ever heard of dumb cane?) That is, maybe 50 mg/ L or so…so it will all come crashing out when the calcium exchanges with the sodium. So sounds as though the easy way is this:

Warm up a big-ass skillet or two. Get a bunch of well-shredded paper or somesuch thing. Soak it in a liter of water and mix it with oh, say, its weight in sand and three times its weight in lye. Boil the water off while stirring till it's dry, then make sure you're wearing your plastic apron and goggles, and let its temperature rise to 220 C. Stir once in a while to keep it well oxidized (perhaps the sand lets air penetrate deeper into the crap, making the oxidation more efficient?), and read a book or something. Pihkal will do. After you have reached the end of the chemical story, the reaction is probably done, and you are probably full of new ideas of what to do with it. Let the pan cool and when it is circa 50 degrees, pour a liter of water into the pan carefully and swish it around till it looks like everything's dissolved. Run the hot water through a coffee filter and chuck the sand somewhere (why not save it for next time?), then add a slight excess of lime to the solution slowly and watch what happens. A whole shitload of crystals should crash out. Get a new filter and collect them, making sure to wash them for optimum flavor and purity. Dry them and at your leisure, convert them back to oxalic acid. There are several ways to do this, but the best way is probably with H2SO4. Assuming you have 100 grams Calcium oxalate, add it 200 ml water heated to 80 C and stirred. Add H2SO4 slowly until nothing changes (use pH paper, I suppose it should be about the mass of your Ca oxalate). Then pour through a filter quickly or just decant off the solution into another beaker, and put it in the fridge. Almost pure oxalic acid crystals will form. According to my little bookie here (no, not him), oxalic acid's solubility goes from 5.73 g/100 g at 10 C to 45.8 g/100 g at 80 C. However, CaSO4 which will be formed by the neutralization is only soluble 0.2 g/100 g, and it doesn't change with temperature, meaning what little remains in solution will not crystallize out. If you want the best yield and don't care so much about purity, instead of recrystallizing you could just boil off the solution after removing the CaSO4 crystals. If the next step in your synth uses sulfuric acid (DMO esterification, for example), there should be no problem.

As for the formates/acetates left in solution, I have no idea how to separate them. Perhaps, since formic acid is strong, if you already had some formic acid, you could add it to the combined salts, and it would only liberate the acetic acid, which could be poured off. Then, add H2SO4 or something to get it all back again, plus the new stuff. More likely just add H2SO4 and distill them off separately.

Somebee should dream about this. It's just too cool not too.

Yaaah HA ha HAAAAA!

ning
(Hive Bee)
11-05-03 16:30
No 468942
      The refs and abstracts
(Rated as: excellent)

Oxalic acid, kirk-othmer encyclopedia of chemical technology, 2nd Ed. (1967), 14 356
---
A review of phys. and chem. properties, manuf. (alkali fusion of cellulose, oxidn. by HNO3, fermentation, and synthesis from formates), economic aspects, anal. and specifications, health and safety factors, uses, and derivs. 42 references.

Acetic, formic, oxalic and succinic acids from corncobs. Swallen, Lloyd C. 1930 CA pat. 302784
---
Acetic, formic, oxalic and succinic acids obtained by the alk. fusion of cellulosic materials are recovered by extg. the fusion products with an approx. 75% by wt. aq. MeOH soln., removing the MeOH by distn. from the filtrate obtained, removing the succinic acid by pptg. with Ca(OAc)2, converting the NaOAc and HCOONa in the resulting soln. into the corresponding acids by treating with H2C2O4, esterifying with BuOH the HCOOH and AcOH thus produced, and finally treating the residue with the original MeOH ext. for the recovery of the H2C2O4.

Production of oxalic acid by alkali fusion of sawdust. Huaxue Shijie (1992), 33(2), 91. Chinese.
---
Sawdust was heated with NaOH at 170-230 C followed by treatment with lime and H2SO4 to give oxalic acid. The optimal prepn. conditions were: NaOH-sawdust ratio 3:1, max. reaction temp. 200 C, and reaction time 6 h. The alkali soln. could be recovered by concn.

Small-scale chemical experiments. 19. Kemisk Tidskrift (1969-1993) (1981) 93(2), 53. Swedish.
---
Lab. expts. in the prepn. of oxalic acid from sawdust and from HCOONa are described. The exptl. prepn. and decompn. of PbC2O4 and of CuC2O4 are also presented.

Oxalic acid from sawdust. Wuhan Daxue Ziran Kexue Xuebao (1959)(No.1) 45. Chinese
---
To an iron vessel contg. a soln. of 240 g. NaOH and 60 g. KOH in 300 ml water was added 100 g sawdust; the mixt. was boiled gently for 3-4 hrs. and evapd. to dryness and <170 C. The residue was transferred to a flat pan (skillet?) and stirred with 8 g petrolatum. When a yellowish syrup formed in the bottom of the pan, 0.1 g KMnO4 in alk. soln. was added gradually, and the mixture was heated 45 min. at 200 C to yield a semisolid and evapd. to dryness at 200 C, but not above that temp. so as to avoid unfavorable carbon formation. When the mixt. became powdery, the heating was stopped, but stirring was continued until the temp. dropped to 100 C. The yellow solid was then mixed with 600 ml H2O and evapd. to 37 deg Be, cooled, and filtered to give a mixture of (CO2Na)2, (CO2K)2, and small amounts of Na2CO3. The ppt. in 24 parts H20 was heated and 80 g CaO in H2O was added, at the bp calcium oxalate was collected, and oxalic acid was liberated with 20 deg Be H2SO4 at 70-100 C. The acid soln. was refiltered hot and concd. Crystn. gave 130 g oxalic acid.

Industrial preparation of oxalic acid from sawdust. Congr. farm. bioquim. peruano y convencion farm. norte, Acta y Trabajos (1953) 301. Spanish.
---
In lab. expts., soft-wood sawdust gives a higher yield of oxalic acid, when treated with a KOH-NaOH mixt., than do hardwoods. (why not just use recycled paper?)

Oxalic acid from sawdust. Optimum conditions for manufacture. J. Industrial & Engineering Chem. (1942), 34, 262.
---
The optimum conditions for the prepn. of oxalic acid(I) by fusion of sawdust with NaOH are studied. The highest yields of I (45.5%) and of AcOH (11.7%) are obtained when a ratio of sawdust to NaOH of 1:3 with a NaOH soln. of 50%, a temp of 200-220 C, a period of 3 hrs., and thin layers of the sawdust-NaOH mixts. are used. Lowering the amt. of NaOH decreases the yields, while increased NaOH does not raise the yield of I to such an extent as to justify the increase in costs. Increase of the temp. over 220 C decreases the yield of I. The increase in the yield of I by using thin layers is due to the ample contact of the fusion mass with air. Besides I and AcOH, 2.5% formic acid, 5.5% methanol, 3% wood oil and an unidentified waxy substance are found in addn. to some noncondensible gasses, mostly CO and CO2. Fusion of balsa, sugar maple, hickory, white and yellow pines, white birch and chestnut shows that a const. ratio exists between the yield of I and AcOH, and the amt. of cellulose in the wood. As the yield of I is slightly higher than that obtained from purified cotton linters, it seems that the lignin in the wood takes part in the formation of I.

Obtaining oxalic acid from wood sawdust. Promyshlennost Organicheskoi Khimii (1938), 5, 489. Russian?
---
Autoclaving sawdust with 2 parts by wt. of calcium hydroxide in the presence of a little water at 120-200 C and 2 atm. of O or air pressure for 1-3 hrs. produced oxalic acid 30-50, AcOH 15-25, formic acid 5-10, succinic acid 5-10 and tartaric acid 1-5%. In contrast to the fusion with NaOH and KOH, this melt is practically free from any resinification and coloring matter, is easily powd. and can be sifted from unaltered cellulosic material. Similar results can be obtained from other cellulosic waste products, such as beet-sugar pulp, flax chaff, corn stalks and sunflower-seed hulls. Com. procedures for the extn. and sepn. of acids in the melt are being investigated.

Oxalic acid from wood-waste. Chemical Age(New York) (1924), 32, 72.
---
100 g of sawdust were fused with 200 g of NaOH, and after lixiviation of the fusion product the oxalic acid was crystd. from the mother liquors. The Na salt was converted to the Ca salt by treatment with lime, and the acid was set free by decompn. of the Ca salt with H2SO4; 35.2 g oxalic acid were obtained. A similar fusion at 220 C yielded 30 g of acid. Fusion of 100 g of wood with 400 g NaOH at 240 C yielded 41 g oxalic acid.

Oxalic acid from sawdust. Japanese patent 37100 (1920)
---
Sawdust, 100 lb, and 62 lbs. Ca(OH)2 are agitated in a vacuum vessel, to which pure O2 heated to 137 C is introduced at the rate of 500cc per 30 min. (don't you love their mixed units?) The sawdust is gradually dissolved, the color being changed to brown and then to yellow. The temp in the vessel is maintained at 105-118 C. The product is washed with warm H20, treated with H2SO4 and steam, filtered and the filtrate concd. to d. of 1.30. On cooling, oxalic acid seps. in a yield of 70-80%

Preparation of oxalic acid from sawdust. Acta Acad. Aboensis Math. et Phys. (1924), 3,203 From Chem. Zentr. 1925, I, 1587. Russion? German?
---
In heating sawdust with NaOH, at least 235-280 g of NaOH per 100 g of sawdust must be used or carbonization takes place. Heating in 2 operations also appears to be advantageous to increase the yield of oxalic acid. The best temp is 230-240, but this can be lowered to 190-200 C if certain oxidizing agents are added. The addn. of inert substances like NaCl and especially sand increases the yield of oxalic acid at any temp. By heating 200-250 g KOH per 100 g of dry sawdust at 190-200 C, yields of 80-100% (based on dry sawdust) of crystd. oxalic acid are obtained. With less KOH there is carbonization and with more KOH the yields are lower unless the temp. is also increased. A max yield of oxalic acid is obtained from 4.0 to 4.24 g-equivs. of a mixt. of NaOH and KOH per 100 g of sawdust at 190-200 C, the ratio of KOH and NaOH being 7:3. By heating with KOH + NaOH or with KOH alone, the amt. of alkali combined with oxalic acid in the reaction product is at most 40% of the total alkali; with NaOH alone (with the addn. of sand) it is at the most 20%. On heating with a mixt. of KOH and Ba(OH)2 or MgO with const. alkali content of 4.24 g-equivs. per 100 g of sawdust (they probably mean 100 g sawdust at a ratio of 4.24 g alkali per gram sawdust), the yield of oxalic acid decreases as the proportion of KOH in the mixt. decreases. No difference in yield was found when sawdust from birch, pine, oak, fir, or aspen wood was heated 3-4 hrs at 200 C with 4.24 g-equivs. of mixts. of KOH and NaOH of const. alkali content. The same yields were also obtained from hydrocellulose.

Reaction products of alkali-sawdust fusion. Acetic, formic, and oxalic acids and methyl alcohol. J. Industrial & Engineering Chem. (Washington D.C.) (1919), 77, 651
--
An investigation to determine the amt. of AcOH obtained from various species of hard wood, in the form of sawdust, by fusion with 50% caustic soda soln. (must be in autoclave if its really a soln.) in the optimum ratio 1:3. The yield of total volatile acid reaches a max at 170 C and 12 hrs. heating with oak and pine, and at 200 C for the same period with maple and elm. A yield of 17 to 20% AcOH with a simultaneous production of 50% oxalic acid and 2.4% MeOH is obtained. The AcOh yield increases with time and temp. up to 230 C for a 3-hr. period, while the oxalic acid formation is highest at 200 C and for long periods of heating, but is independent of the AcOH produced. Lower temp promotes the formation of both formic acid and AcOH to approx 15% each. A 91% caustic recovery was found to be possible.

Notes on the manufacture of oxalic acid. Revue des Produits Chimiques (1916) 13, 259. French.
---
--SNIP OUT HNO3 OXIDATION PART--
As regards the formation of oxalic acid by the action of caustic alkalies at high temps upon carbohydrates in accordance with the reactions of Vauquelin and Gay-Lussac, this reaction has been utilized for manufacturing purposes since 1856 by Messrs. Roberts, Dale & Co., of Manchester, England. As raw material wood sawdust is generally used; 40 parts of this are preferably treated with 100 parts caustic alkali made into a soln. of 37 deg Be. While KOH has been found to yield the best results, it may be replaced in part by NaOH; a mixt. of 4 parts of KOH with 6 parts of NaOH yields the best results. This is a rather complicated reaction from the chemical point of view. It is probably due to the hydrolysis of the cellulose molecule and oxidation of the hydrolytic products. The manuf. is carried out in two stages, the first stage being the heating of the sawdust with the caustic alkali in iron boilers preferably by direct fire at a temp of 200-250 C. H and hydrocarbons are liberated. The mass, which assumes a dark color, is then spread on plates and worked in a heated oven until a completely dry powder is obtained; this is sol in water and contains up to 30% of oxalic acid. It is then treated with cold water to remove the alkali in excess and the carbonates formed in the reaction, which after evapn. of the soln. are recovered. Na oxalate, being less sol in cold water (1 part in 30 water), remains in the mass. it is converted to Ca oxalate which is decomposed by dil. H2SO4, the resulting oxalic acid being then crystd. Some factories make this process continuous by making use of a rotatable heated cylinder in the interior of which a conveyor screw is rotated in the inverse direction. This carries the heated mass through the cylinder and ejects it as a porous substance after the reaction is finished. The yield is thereby increased to about 80% of the sawdust employed. Inasmuch as most of the alkali is recovered, the chief expense is for heating and evapn. of the solns. obtained. (--snip--) An improvement of the process consists in the addition of heavy hydrocarbons (vaseline, mineral oil) to the initial charge. The yield is thereby increased to 140 parts oxalic acid to 100 parts of sawdust employed. According to french patent 263,822, the first stage of the reaction is preferably carried out in vacuo and in a boiler containing an agitator, whereby the temp of reaction may be lowered to 180 C. For the second stage heated plates are used upon which the mass is kept agitated in contact with the air until it becomes colorless. The process thereby becomes more regular and the oxalic acid obtained is whiter than when made according to the old process.

Preparation of Oxalic Acid by Fusing Sawdust with Potassium Hydroxide. Chemiker-Zeitung (1911), 35, 853. German.
---
A series of investigations to det. the conditions under which the best yields of oxalic acid are to be obtained by the fusion of cellulose materials with KOH. 3 g of purified cotton were soaked in KOH soln. (12 g KOH per 20 cc water) and heated in a Ni crucible. The best yield (3.72 g oxalic acid from 3 g cotton) was obtained when the mass was heated slowly and with stirring to 280 C and, after action had ceased, was cooled slowly. A white powder was thus obtained, sol. in H2O, the soln. giving no ppt. with dil. acids. The yield was not increased by the use of stronger KOH solns. and was greatly decreased when the fusion was carried on at 225 C. When cotton was soaked in a soln. of 13 g KOH and 1 g oxalic acid in 30 cc H2O and heated as before, the yield was considerably increased (5.16 g oxalic acid from 3 g Watte (??)) The addition of KNO3 or KClO3 did not increase the yield. The conditions cited above applied also when oak sawdust was used as the raw material, the yield in this case being about the same as the yield from pure cellulose, vis., 3.66 g oxalic acid from 3 g sawdust. It appears therefore that the lignin constituents of the sawdust go also to form oxalic acid. This was further shown by allowing 3 g sawdust to stand 3 days with 10% KOH soln., filtering and evapg. the filtrate and wash H2O to dryness. A small yield of oxalic acid was obtained (1.81 g oxalic acid from 3 g sawdust).

Conversion of jute stick into oxalic acid. Scientific Researches (Dacca) (1969), 6 (1-2), 58. English.
---
The effects of varying the ratio of alkali to dry jute stick powder (2:1-3.5:1), temp (170-210), heating time (1-4 h), and depth of the fusion mass (0.2-0.65 in) were obsd. for the alkali fusion conversion of jute stick into oxalic acid. Expts. were run by both the deep run and shallow pan methods, with the latter giving superior results. Color changes during reaction were noted. Under optimum conditions, an avg. conversion of 42.56, avg. actual yield of 32.35, and avg. recoverable alkali of 83.66% were obtained.

Half-a-pint would be proud. Look at all the precursors we can get from paper and wood!

gsus
(Hive Bee)
11-05-04 06:23
No 539812
      one of the above refs

Oxalic Acid From Sawdust - Optimum Conditions For Manufacture
D.F. Othmer, C.H. Gamer, and J.J. Jacobs, Jr.
Ind. Eng. Chem. 34, 262-267 (1942)

yeah, i know - but i was looking through IEC for something else, saw this, and remembered this thread.

...they look, but do not see, and they listen, but do not hear or understand.

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	All 3 posts		Subject: Oxalic and formic acid from sawdust		Please login to post		Down


		ning (Hive Bee) 11-05-03 16:29 No 468940				Oxalic and formic acid from sawdust
						please note, it was dark and early. ning was a little spun and worked up. If this post seems a little...crazy, well, that's because it is. Refs and abstracts on oxalic acid production by fusion of alkali with cellulose-containing materials. aka How to make even more precursors from wood, paper, and lye in your kitchen. Who's got a Big Library of Third-World-Nation Scientific Journals? Maybe someone could get some of these papers? They are all pretty obscure. Perhaps the "developed world" has no use for such technology anymore? Guys, you can't get much more OTC than a cast iron skillet, some sawdust or shredded paper, and lye. And you can get more than 30% BY WEIGHT oxalic acid back! Forget that nasty nitric acid method, the alkali fusion method is just the mass production method for oxalic acid we've been waiting for. I needn't remind you that with large quantities of oxalic acid in hand, if a really deprived bee needed some glycerin, they could make that from cooking oil or lard…about 130 grams per kilo of oil saponified. I know, it's not a lot, but if you can't get it any other way…So if this whole dimethy oxalate methylation thing pans out, halfapint's dream of a "jungle synth" might not be so farfetched. From those two, formic acid, which can also be made into formamide with urea in high yield(Not going to tell you where to get that one…look down…), allyl alcohol, as well as the methanol and acetic acid if necessary, are all makeable from the most basic elements of the earth--fat, lye, urine, and wood. Let's see the DEA and its lubricious triletteral brethren try to control those! Squirm Wormy, Squirm!!! The war is lost! Wake up! It's just a matter of time! Note, some of the abstracts mention up to 15% formic acid production by weight by changing reaction conditions. (lower temperature) From sawdust! Not as good as the oxalic acid yield, but still, Nice. Also, most notably acetic acid may be present in very non-trivial amounts. With the availability of vinegar, it's kind of a non-issue, but some bees may have real use for such things. Got a ketene lamp? Waste not, want not… The separation is the tricky part, but by using lime to convert the acids to their calcium salts, removing the oxalic acid is easy, because the other two acids' calcium salts are soluble in water (~200 g/L), while calcium oxalate is notoriously insoluble. (That's why kidney stones suck. Some plants use little crystals of calcium oxalate as needles to carry their poison through the skin. Ever heard of dumb cane?) That is, maybe 50 mg/ L or so…so it will all come crashing out when the calcium exchanges with the sodium. So sounds as though the easy way is this: Warm up a big-ass skillet or two. Get a bunch of well-shredded paper or somesuch thing. Soak it in a liter of water and mix it with oh, say, its weight in sand and three times its weight in lye. Boil the water off while stirring till it's dry, then make sure you're wearing your plastic apron and goggles, and let its temperature rise to 220 C. Stir once in a while to keep it well oxidized (perhaps the sand lets air penetrate deeper into the crap, making the oxidation more efficient?), and read a book or something. Pihkal will do. After you have reached the end of the chemical story, the reaction is probably done, and you are probably full of new ideas of what to do with it. Let the pan cool and when it is circa 50 degrees, pour a liter of water into the pan carefully and swish it around till it looks like everything's dissolved. Run the hot water through a coffee filter and chuck the sand somewhere (why not save it for next time?), then add a slight excess of lime to the solution slowly and watch what happens. A whole shitload of crystals should crash out. Get a new filter and collect them, making sure to wash them for optimum flavor and purity. Dry them and at your leisure, convert them back to oxalic acid. There are several ways to do this, but the best way is probably with H2SO4. Assuming you have 100 grams Calcium oxalate, add it 200 ml water heated to 80 C and stirred. Add H2SO4 slowly until nothing changes (use pH paper, I suppose it should be about the mass of your Ca oxalate). Then pour through a filter quickly or just decant off the solution into another beaker, and put it in the fridge. Almost pure oxalic acid crystals will form. According to my little bookie here (no, not him), oxalic acid's solubility goes from 5.73 g/100 g at 10 C to 45.8 g/100 g at 80 C. However, CaSO4 which will be formed by the neutralization is only soluble 0.2 g/100 g, and it doesn't change with temperature, meaning what little remains in solution will not crystallize out. If you want the best yield and don't care so much about purity, instead of recrystallizing you could just boil off the solution after removing the CaSO4 crystals. If the next step in your synth uses sulfuric acid (DMO esterification, for example), there should be no problem. As for the formates/acetates left in solution, I have no idea how to separate them. Perhaps, since formic acid is strong, if you already had some formic acid, you could add it to the combined salts, and it would only liberate the acetic acid, which could be poured off. Then, add H2SO4 or something to get it all back again, plus the new stuff. More likely just add H2SO4 and distill them off separately. Somebee should dream about this. It's just too cool not too. Yaaah HA ha HAAAAA!



		ning (Hive Bee) 11-05-03 16:30 No 468942				The refs and abstracts (Rated as: excellent)
						Oxalic acid, kirk-othmer encyclopedia of chemical technology, 2nd Ed. (1967), 14 356 --- A review of phys. and chem. properties, manuf. (alkali fusion of cellulose, oxidn. by HNO3, fermentation, and synthesis from formates), economic aspects, anal. and specifications, health and safety factors, uses, and derivs. 42 references. Acetic, formic, oxalic and succinic acids from corncobs. Swallen, Lloyd C. 1930 CA pat. 302784 --- Acetic, formic, oxalic and succinic acids obtained by the alk. fusion of cellulosic materials are recovered by extg. the fusion products with an approx. 75% by wt. aq. MeOH soln., removing the MeOH by distn. from the filtrate obtained, removing the succinic acid by pptg. with Ca(OAc)2, converting the NaOAc and HCOONa in the resulting soln. into the corresponding acids by treating with H2C2O4, esterifying with BuOH the HCOOH and AcOH thus produced, and finally treating the residue with the original MeOH ext. for the recovery of the H2C2O4. Production of oxalic acid by alkali fusion of sawdust. Huaxue Shijie (1992), 33(2), 91. Chinese. --- Sawdust was heated with NaOH at 170-230 C followed by treatment with lime and H2SO4 to give oxalic acid. The optimal prepn. conditions were: NaOH-sawdust ratio 3:1, max. reaction temp. 200 C, and reaction time 6 h. The alkali soln. could be recovered by concn. Small-scale chemical experiments. 19. Kemisk Tidskrift (1969-1993) (1981) 93(2), 53. Swedish. --- Lab. expts. in the prepn. of oxalic acid from sawdust and from HCOONa are described. The exptl. prepn. and decompn. of PbC2O4 and of CuC2O4 are also presented. Oxalic acid from sawdust. Wuhan Daxue Ziran Kexue Xuebao (1959)(No.1) 45. Chinese --- To an iron vessel contg. a soln. of 240 g. NaOH and 60 g. KOH in 300 ml water was added 100 g sawdust; the mixt. was boiled gently for 3-4 hrs. and evapd. to dryness and <170 C. The residue was transferred to a flat pan (skillet?) and stirred with 8 g petrolatum. When a yellowish syrup formed in the bottom of the pan, 0.1 g KMnO4 in alk. soln. was added gradually, and the mixture was heated 45 min. at 200 C to yield a semisolid and evapd. to dryness at 200 C, but not above that temp. so as to avoid unfavorable carbon formation. When the mixt. became powdery, the heating was stopped, but stirring was continued until the temp. dropped to 100 C. The yellow solid was then mixed with 600 ml H2O and evapd. to 37 deg Be, cooled, and filtered to give a mixture of (CO2Na)2, (CO2K)2, and small amounts of Na2CO3. The ppt. in 24 parts H20 was heated and 80 g CaO in H2O was added, at the bp calcium oxalate was collected, and oxalic acid was liberated with 20 deg Be H2SO4 at 70-100 C. The acid soln. was refiltered hot and concd. Crystn. gave 130 g oxalic acid. Industrial preparation of oxalic acid from sawdust. Congr. farm. bioquim. peruano y convencion farm. norte, Acta y Trabajos (1953) 301. Spanish. --- In lab. expts., soft-wood sawdust gives a higher yield of oxalic acid, when treated with a KOH-NaOH mixt., than do hardwoods. (why not just use recycled paper?) Oxalic acid from sawdust. Optimum conditions for manufacture. J. Industrial & Engineering Chem. (1942), 34, 262. --- The optimum conditions for the prepn. of oxalic acid(I) by fusion of sawdust with NaOH are studied. The highest yields of I (45.5%) and of AcOH (11.7%) are obtained when a ratio of sawdust to NaOH of 1:3 with a NaOH soln. of 50%, a temp of 200-220 C, a period of 3 hrs., and thin layers of the sawdust-NaOH mixts. are used. Lowering the amt. of NaOH decreases the yields, while increased NaOH does not raise the yield of I to such an extent as to justify the increase in costs. Increase of the temp. over 220 C decreases the yield of I. The increase in the yield of I by using thin layers is due to the ample contact of the fusion mass with air. Besides I and AcOH, 2.5% formic acid, 5.5% methanol, 3% wood oil and an unidentified waxy substance are found in addn. to some noncondensible gasses, mostly CO and CO2. Fusion of balsa, sugar maple, hickory, white and yellow pines, white birch and chestnut shows that a const. ratio exists between the yield of I and AcOH, and the amt. of cellulose in the wood. As the yield of I is slightly higher than that obtained from purified cotton linters, it seems that the lignin in the wood takes part in the formation of I. Obtaining oxalic acid from wood sawdust. Promyshlennost Organicheskoi Khimii (1938), 5, 489. Russian? --- Autoclaving sawdust with 2 parts by wt. of calcium hydroxide in the presence of a little water at 120-200 C and 2 atm. of O or air pressure for 1-3 hrs. produced oxalic acid 30-50, AcOH 15-25, formic acid 5-10, succinic acid 5-10 and tartaric acid 1-5%. In contrast to the fusion with NaOH and KOH, this melt is practically free from any resinification and coloring matter, is easily powd. and can be sifted from unaltered cellulosic material. Similar results can be obtained from other cellulosic waste products, such as beet-sugar pulp, flax chaff, corn stalks and sunflower-seed hulls. Com. procedures for the extn. and sepn. of acids in the melt are being investigated. Oxalic acid from wood-waste. Chemical Age(New York) (1924), 32, 72. --- 100 g of sawdust were fused with 200 g of NaOH, and after lixiviation of the fusion product the oxalic acid was crystd. from the mother liquors. The Na salt was converted to the Ca salt by treatment with lime, and the acid was set free by decompn. of the Ca salt with H2SO4; 35.2 g oxalic acid were obtained. A similar fusion at 220 C yielded 30 g of acid. Fusion of 100 g of wood with 400 g NaOH at 240 C yielded 41 g oxalic acid. Oxalic acid from sawdust. Japanese patent 37100 (1920) --- Sawdust, 100 lb, and 62 lbs. Ca(OH)2 are agitated in a vacuum vessel, to which pure O2 heated to 137 C is introduced at the rate of 500cc per 30 min. (don't you love their mixed units?) The sawdust is gradually dissolved, the color being changed to brown and then to yellow. The temp in the vessel is maintained at 105-118 C. The product is washed with warm H20, treated with H2SO4 and steam, filtered and the filtrate concd. to d. of 1.30. On cooling, oxalic acid seps. in a yield of 70-80% Preparation of oxalic acid from sawdust. Acta Acad. Aboensis Math. et Phys. (1924), 3,203 From Chem. Zentr. 1925, I, 1587. Russion? German? --- In heating sawdust with NaOH, at least 235-280 g of NaOH per 100 g of sawdust must be used or carbonization takes place. Heating in 2 operations also appears to be advantageous to increase the yield of oxalic acid. The best temp is 230-240, but this can be lowered to 190-200 C if certain oxidizing agents are added. The addn. of inert substances like NaCl and especially sand increases the yield of oxalic acid at any temp. By heating 200-250 g KOH per 100 g of dry sawdust at 190-200 C, yields of 80-100% (based on dry sawdust) of crystd. oxalic acid are obtained. With less KOH there is carbonization and with more KOH the yields are lower unless the temp. is also increased. A max yield of oxalic acid is obtained from 4.0 to 4.24 g-equivs. of a mixt. of NaOH and KOH per 100 g of sawdust at 190-200 C, the ratio of KOH and NaOH being 7:3. By heating with KOH + NaOH or with KOH alone, the amt. of alkali combined with oxalic acid in the reaction product is at most 40% of the total alkali; with NaOH alone (with the addn. of sand) it is at the most 20%. On heating with a mixt. of KOH and Ba(OH)2 or MgO with const. alkali content of 4.24 g-equivs. per 100 g of sawdust (they probably mean 100 g sawdust at a ratio of 4.24 g alkali per gram sawdust), the yield of oxalic acid decreases as the proportion of KOH in the mixt. decreases. No difference in yield was found when sawdust from birch, pine, oak, fir, or aspen wood was heated 3-4 hrs at 200 C with 4.24 g-equivs. of mixts. of KOH and NaOH of const. alkali content. The same yields were also obtained from hydrocellulose. Reaction products of alkali-sawdust fusion. Acetic, formic, and oxalic acids and methyl alcohol. J. Industrial & Engineering Chem. (Washington D.C.) (1919), 77, 651 -- An investigation to determine the amt. of AcOH obtained from various species of hard wood, in the form of sawdust, by fusion with 50% caustic soda soln. (must be in autoclave if its really a soln.) in the optimum ratio 1:3. The yield of total volatile acid reaches a max at 170 C and 12 hrs. heating with oak and pine, and at 200 C for the same period with maple and elm. A yield of 17 to 20% AcOH with a simultaneous production of 50% oxalic acid and 2.4% MeOH is obtained. The AcOh yield increases with time and temp. up to 230 C for a 3-hr. period, while the oxalic acid formation is highest at 200 C and for long periods of heating, but is independent of the AcOH produced. Lower temp promotes the formation of both formic acid and AcOH to approx 15% each. A 91% caustic recovery was found to be possible. Notes on the manufacture of oxalic acid. Revue des Produits Chimiques (1916) 13, 259. French. --- --SNIP OUT HNO3 OXIDATION PART-- As regards the formation of oxalic acid by the action of caustic alkalies at high temps upon carbohydrates in accordance with the reactions of Vauquelin and Gay-Lussac, this reaction has been utilized for manufacturing purposes since 1856 by Messrs. Roberts, Dale & Co., of Manchester, England. As raw material wood sawdust is generally used; 40 parts of this are preferably treated with 100 parts caustic alkali made into a soln. of 37 deg Be. While KOH has been found to yield the best results, it may be replaced in part by NaOH; a mixt. of 4 parts of KOH with 6 parts of NaOH yields the best results. This is a rather complicated reaction from the chemical point of view. It is probably due to the hydrolysis of the cellulose molecule and oxidation of the hydrolytic products. The manuf. is carried out in two stages, the first stage being the heating of the sawdust with the caustic alkali in iron boilers preferably by direct fire at a temp of 200-250 C. H and hydrocarbons are liberated. The mass, which assumes a dark color, is then spread on plates and worked in a heated oven until a completely dry powder is obtained; this is sol in water and contains up to 30% of oxalic acid. It is then treated with cold water to remove the alkali in excess and the carbonates formed in the reaction, which after evapn. of the soln. are recovered. Na oxalate, being less sol in cold water (1 part in 30 water), remains in the mass. it is converted to Ca oxalate which is decomposed by dil. H2SO4, the resulting oxalic acid being then crystd. Some factories make this process continuous by making use of a rotatable heated cylinder in the interior of which a conveyor screw is rotated in the inverse direction. This carries the heated mass through the cylinder and ejects it as a porous substance after the reaction is finished. The yield is thereby increased to about 80% of the sawdust employed. Inasmuch as most of the alkali is recovered, the chief expense is for heating and evapn. of the solns. obtained. (--snip--) An improvement of the process consists in the addition of heavy hydrocarbons (vaseline, mineral oil) to the initial charge. The yield is thereby increased to 140 parts oxalic acid to 100 parts of sawdust employed. According to french patent 263,822, the first stage of the reaction is preferably carried out in vacuo and in a boiler containing an agitator, whereby the temp of reaction may be lowered to 180 C. For the second stage heated plates are used upon which the mass is kept agitated in contact with the air until it becomes colorless. The process thereby becomes more regular and the oxalic acid obtained is whiter than when made according to the old process. Preparation of Oxalic Acid by Fusing Sawdust with Potassium Hydroxide. Chemiker-Zeitung (1911), 35, 853. German. --- A series of investigations to det. the conditions under which the best yields of oxalic acid are to be obtained by the fusion of cellulose materials with KOH. 3 g of purified cotton were soaked in KOH soln. (12 g KOH per 20 cc water) and heated in a Ni crucible. The best yield (3.72 g oxalic acid from 3 g cotton) was obtained when the mass was heated slowly and with stirring to 280 C and, after action had ceased, was cooled slowly. A white powder was thus obtained, sol. in H2O, the soln. giving no ppt. with dil. acids. The yield was not increased by the use of stronger KOH solns. and was greatly decreased when the fusion was carried on at 225 C. When cotton was soaked in a soln. of 13 g KOH and 1 g oxalic acid in 30 cc H2O and heated as before, the yield was considerably increased (5.16 g oxalic acid from 3 g Watte (??)) The addition of KNO3 or KClO3 did not increase the yield. The conditions cited above applied also when oak sawdust was used as the raw material, the yield in this case being about the same as the yield from pure cellulose, vis., 3.66 g oxalic acid from 3 g sawdust. It appears therefore that the lignin constituents of the sawdust go also to form oxalic acid. This was further shown by allowing 3 g sawdust to stand 3 days with 10% KOH soln., filtering and evapg. the filtrate and wash H2O to dryness. A small yield of oxalic acid was obtained (1.81 g oxalic acid from 3 g sawdust). Conversion of jute stick into oxalic acid. Scientific Researches (Dacca) (1969), 6 (1-2), 58. English. --- The effects of varying the ratio of alkali to dry jute stick powder (2:1-3.5:1), temp (170-210), heating time (1-4 h), and depth of the fusion mass (0.2-0.65 in) were obsd. for the alkali fusion conversion of jute stick into oxalic acid. Expts. were run by both the deep run and shallow pan methods, with the latter giving superior results. Color changes during reaction were noted. Under optimum conditions, an avg. conversion of 42.56, avg. actual yield of 32.35, and avg. recoverable alkali of 83.66% were obtained. Half-a-pint would be proud. Look at all the precursors we can get from paper and wood!



		gsus (Hive Bee) 11-05-04 06:23 No 539812				one of the above refs
						Oxalic Acid From Sawdust - Optimum Conditions For Manufacture D.F. Othmer, C.H. Gamer, and J.J. Jacobs, Jr. Ind. Eng. Chem. 34, 262-267 (1942) yeah, i know - but i was looking through IEC for something else, saw this, and remembered this thread. ...they look, but do not see, and they listen, but do not hear or understand.

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