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All 25 posts Subject: Knoevenagel with various catalysts Please login to post Down

Barium
(Stranger)
06-11-02 15:08
No 319830
      Knoevenagel with various catalysts
(Rated as: excellent)

As you can see there is great many catalysts which can be employed in the Knoevenagel-Walter.

Benzaldehyde Nitroethane   n-butylamine EtOH reflux    85% Ref 1
Benzaldehyde Nitroethane   ethylenediamine   50 deg C 76% Ref 2
4-OH-benzaldehyde Nitromethane anilline 100 deg C    79% Ref 3
Piperonal Nitromethane ethylamine 8-10 deg C 97% Ref 4
Piperonal Nitroethane   ethylamine 20 deg C 87% Ref 5
Piperonal Nitroethane   n-pentylamine    20 deg C 87% Ref 5
Piperonal Nitroethane   methylamine    20 deg C 87% Ref 5
3-MeO-benzaldehyde    Nitroethane   n-butylamine EtOH reflux    54% Ref 3
4-MeO-benzaldehyde    Nitroethane   ethylenediamine   80 deg C 100% Ref 2
4-MeO-benzaldehyde    Nitropropane n-butylamine EtOH reflux    90% Ref 1
4-MeO-benzaldehyde    1-Nitrobutane   n-butylamine EtOH reflux    90% Ref 1
3-OH-4-MeO-benzaldehyde    Nitromethane methylamine    0-20 deg C 80% Ref 6
3-MeO-4-OH-benzaldehyde    Nitromethane methylamine    20 deg C 81% Ref 6
3-MeO-4-OH-benzaldehyde    Nitromethane ethylenediamine   20 deg C 95% Ref 2
3-MeO-4-OH-benzaldehyde    Nitroethane   methylamine    20 deg C 79% Ref 5
3-MeO-4,5-MDO-benzaldehyde Nitromethane n-pentylamine    20 deg C 90% Ref 8
3,5-diMeO-4-OH-benzaldehyde Nitromethane methylamine    MeOH/20 deg C    97% Ref 9
3,5-diMeO-4-EtO-benzaldehyde Nitromethane NH4 acetate    MeOH reflux    65% Ref 9
2,3,4,6-tetraMeO-benzaldehyde Nitromethane NH4 acetate    MeOH reflux    93% Ref 10

Ref 1 J. Org. Chem., 15, 8 (1950)
Ref 2 Zh. Prikl. Khim., 31, 663 (1958)
Ref 3 J. Am. Chem. Soc., 74, 4489 (1952)
Ref 4 J. Am. Chem. Soc., 73, 5556 (1951)
Ref 5 JOC., 16, 221 (1951)
Ref 6 J. Am. Chem. Soc., 72, 2781 (1950)
Ref 7 JOC. 16, 221 (1951)
Ref 8 J. Am. Chem. Soc., 71, 2211 (1949)
Ref 9 J. Am. Chem. Soc., 76, 5556 (1954)
Ref 10 JOC. 20, 104 (1955)

Barium
(Newbee)
06-11-02 15:25
No 319833
      It´s not a beautiful thing but I don´t have the ...

It´s not a beautiful thing but I don´t have the energy to edit it to look cute.. tongue

By the way...I´m now a newbee.... laugh

Antoncho
(Official Hive Translator)
06-11-02 16:40
No 319845
      Interesting....

.......but why there's no mention of dialkylammonium salts?

Can they bee used as bases in this rxn? Can they not?

Antoncho's asking 'cause there's some guy who isn't Antoncho who has a practical interest in this rxn using dimethylammonium acetate smile

BTW, Barium, congratulations w/your new title! wink Keep up the good work wink Your posts are quite interesting to read, shall i say wink

Antoncho

Rhodium
(Chief Bee)
06-11-02 16:44
No 319849
User Picture       Yes, dialkylammoniums can also be used, there are ...

Yes, dialkylammoniums can also be used, there are MANY possible catalysts out there.

Are the aldimines true intermediates even in the one-pot syntheses, or does the amines simply act as a base?

Barium
(Newbee)
06-11-02 16:46
No 319850
      I´ll bet

Thanks Antoncho.. wink
I´ve seen dimethylamine, diethylamine and triethylamine, as free bases and salts, be used as catalysts. Let´s see if I have some of the references nearby. I´ll post what I find.

hypo
(Hive Addict)
06-11-02 17:14
No 319856
User Picture       Knoevenagel

just for the record and the fse: it's Knoevenagel without 'h'.

Rhodium
(Chief Bee)
06-11-02 17:22
No 319858
      What is this about Knoevenagel-Walther?

What is this about Knoevenagel-Walter? I thought this specific case of a Knoevenagel reaction (RNO2 + RCHO) was called "Henry reaction".

hypo
(Hive Addict)
06-11-02 17:43
No 319861
User Picture       google finds it all :)

none of my oc books knows it under that name, but:

https://www.rhodium.ws/chemistry/mda.dalcason.html:

"If the appropriate piperonals are available to react with nitroethane, the Knoevenagel-Walter condensation, will permit the synthesis of ring-substituted analogs [24,29] through nitropropene intermediates (Fig. 5). "

lugh
(Moderator)
06-11-02 19:16
No 319881
      Walter

Walter co-authored Ber 37 4502 (1904) with Knoevenagel, in which it was first reported nitrostyrenes were obtained in good yield using amine catalysts smile

Rhodium
(Chief Bee)
06-11-02 19:24
No 319884
User Picture       Aha - and the "Henry Reaction" reference is from ...

Aha - and the "Henry Reaction" reference is from where?

java
(Newbee)
06-11-02 19:50
No 319891
      re-Henry reaction

Henry reaction;Kamlet reaction.
L.Henry, Compt. rend. 120,1265 (18950; J. Kamlet, US. PAT. 2,151,517 (1939);C.A. 33,5003 (1939)
Formation of nitroalcohols by an aldol-type condensation of nitroparaffins with aldehydes in the presence of base(Henry) or by the condensation of sodium salts of acinitroparaffins with the sodium bisulfite additon products of aldehydes in the presence of a trace of alkali or weak acid (Kamlet). widely used in the surar chemistry Ref. Merck Index 9th edition Organic Name reactions page 42[b]

Boobsie
(Stranger)
06-12-02 00:30
No 319979
      Shulgin mentions performing this reaction on ...

Shulgin mentions performing this reaction on piperonal with reactants in MeOH solution and aqueous NaOH as a base under the MDA entry, PiHKAL 100 http://www.erowid.org/library/books_online/pihkal/pihkal100.shtml

Whether this would work well with other aldehydes is beyond me.

Rhodium
(Chief Bee)
06-12-02 01:27
No 320001
User Picture       NaOH catalyzed condensation

Here is a detailed description of such a procedure: https://www.rhodium.ws/chemistry/mdp2np.html

Antibody2
(Rehabilitated)
06-13-02 01:34
No 320535
      i like that one alot too Rhodium, any reason to ...

i like that one alot too Rhodium, any reason to think it wouldn't work for nitromethane condensation as well?

Rhodium
(Chief Bee)
06-13-02 02:27
No 320554
User Picture       nitrostyrene

In Vogel's "Practical Organic Chemistry" 5th Ed. they use that method to make plain nitrostyrene, 3,4-methylenedioxynitrostyrene and 2,4-dimethoxynitrostyrene. If you want to I can OCR those two pages for you.

Antibody2
(Rehabilitated)
06-13-02 02:59
No 320562
      yes

i'd appreciate that Rhodium! thanks

Rhodium
(Chief Bee)
06-13-02 03:22
No 320567
User Picture       NITROSTYRENE
(Rated as: excellent)

Vogel's "Practical Organic Chemistry" 5th Ed.p 1035-1036

Experiment 6.136 NITROSTYRENE

Ph-CHO + Me-NO2 -NaOH-> PhCH=CHNO2

Equip a 1500-ml three-necked flask with a thermometer, mechanical stirrer and a dropping funnel. Place 61 g (54 ml, 1 mol) of nitromethane (1), 106g (101 ml, 1 mol) of purified benzaldehyde and 200 ml of methanol in the flask and cool it with a mixture of ice and salt to about -10 °C. Dissolve 42g of sodium hydroxide in 40-50 ml of water, cool and dilute to 100 ml with ice and water; place this cold solution in the dropping funnel. Add the sodium hydroxide solution, with vigorous stirring, to the nitromethane mixture at such a rate that the temperature is held at 10-15 °C. Introduce the first few ml cautiously since, after a short induction period, the temperature may rise to 30°C or higher; check the rise in temperature, if necessary, by adding a little crushed ice to the reaction mixture. A bulky white precipitate forms; if the mixture becomes so thick that stirring is difficult, add about 10 ml of methanol. After standing for about 15 minutes, add 700 ml of ice-water containing crushed ice; the temperature should be below 5°C. Run the resulting cold solution immediately from a dropping funnel and with stirring into 500 ml of 4 M hydrochloric acid contained in a 3-litre flask; adjust the rate of addition so that the stream just fails to break into drops. A pale yellow crystalline precipitate separates almost as soon as the alkaline solution mixes with the acid. The solid settles to the bottom of the vessel when the stirrer is stopped. Decant most of the cloudy liquid layer, filter the residue by suction and wash it with water until free from chlorides. Transfer the solid to a beaker immersed in hot water; two layers form and on cooling again, the lower layer of nitrostyrene solidifies; pour off the upper water layer. Dissolve the crude nitrostyrene in 85 ml of hot ethanol. (CAUTION: nitrostyrene vapours are irritating to the nose and eyes, and the skin of the face is sensitive to the solid.) Filter through a hotwater funnel and cool until crystallisation is complete. The yield of pure nitrostyrene, m.p. 57-58°C, is 125 g (85%).

Note 1: The commercial material may be redistilled and the fraction having b.p.100-102°C collected.

Cognate preparations.

3,4-Methylenedioxy-nitrostyrene.

In a 250-ml round-bottomed flask mix 30g (0.20 mol) of 3,4-methylenedioxybenzaldehyde (piperonal), 13.4 g (0.22 mol) of nitromethane, 7.8 g (0.1 mol) of ammonium acetate and 50 ml of glacial acid. Attach a reflux condenser, and boil the mixture under gentle reflux for 1 hour. Pour the reaction mixture with stirring into a large excess of ice-water (about 1 litre). When all the ice has melted, filter off the crude product under suction and recrystallise from a mixture of absolute ethanol and acetone (about 2:1 v/v). Almost pure yellow crystals of the nitrostyrene, m.p. 161 °C, are obtained. The yield is 23.3 g (60%). Further recrystallisation from the same solvent yields the pure compound, m.p. 162°C.

2,4-Dimethoxy-m-nitrostyrene.

Follow the above procedure, but use 33.2g (0.20 mol) of 2,4-dimethoxybenzaldehyde as the starting material. The yield of recrystallised product (yellow crystals, m.p. 103°C) is 28.5 g (68%). Further recrystallisation gives pure product of m.p. 105°C.

Rhodium
(Chief Bee)
06-13-02 22:16
No 320904
User Picture       2,5-Dimethoxynitrostyrene w/ NaOH catalyst
(Rated as: excellent)

2,5-Dimethoxynitrostyrene
JOC 52, 2945-2947 (1987)

A mixture of 2,5-dimethoxybenzaldehyde (1.97 g, 11.8 mmol) and nitromethane (0.72 g, 11.8 mmol) in methanol (200 mL) was stirred at room temperature until the solids dissolved. The solution was cooled to 0°C and a 10.5 M NaOH solution (2 mL) was added dropwise over 20 min. The alkaline solution was added slowly to a 4% HCl solution (200 mL) maintained at 60°C. The pale yellow amorphous solid that formed was filtered and washed with water (200 mL). The crude product was recrystallized from absolute ethanol to give yellow needles (2.11 g, 85%).
mp 121-123°C; IR 3100, 1620, 1500, 1351 cm^-1; ¹H NMR (CDCl₃) δ 7.9 (dd, J=14 Hz, 2 H), 6.88 (d, J=3 Hz, 3 H), 3.85 (s, 3 H), and 3.75 (s, 3 H).

Preparation of 10.5 M NaOH: Dissolve 10.5g sodium hydroxide under cooling in 20ml water, and after cooling dilute the solution to exactly 25ml.

Sunlight
(Pioneer Researcher)
06-14-02 21:02
No 321361
      Good

It is fucking good !!! mmm, well the volumes are big.

Bwiti
(PVC-Analog Taste-Tester)
06-15-02 19:42
No 321793
User Picture       Isopropylamine in methanol works great for ...

Isopropylamine in methanol works great for nitroethane/benzaldehyde. cool
Love my country, fear my government.

Boobsie
(Stranger)
06-16-02 21:58
No 322208
      SWIM is thinking that this could easily lead to a ...

SWIM is thinking that this could easily lead to a one-pot synth of 2C-H, using the Zn/HCl reduction posted by Sunlight, taking advantage of the fact that the yields are pretty high and the nitrostyrene will already be in an acidic medium that would only need be further acidified for the reduction step.

SWIM doesn't know how this could affect yields (probably negatively), and given the ease of filtering everything and moving to a different flask it probably isn't worth it.

Rhodium
(Chief Bee)
06-16-02 22:31
No 322213
User Picture       Bad idea. Always isolate your reaction ...

Bad idea. Always isolate your reaction intermediates to remove by-products.

Aurelius
(Hive Bee)
06-17-02 19:55
No 322491
      nitroethane

Hey Bwiti, did you use the nitroethane source aurelius sent you? just curious. and you didn't tell aurelius you've done nitropropenes, email the details.

Rhodium
(Chief Bee)
05-13-04 23:50
No 506995
User Picture       Knoevenagel's first Nitrostyrene article
(Rated as: good read)

Condensation aliphatischer Nitrokörper mit aromatischen Aldehyden durch organische Basen
E. Knoevenagel & L. Walter
Chem. Ber. 37, 4502-4510 (1904) (https://www.rhodium.ws/pdf/knoevenagel.condensation.pdf)

The first article on nitroalkene preparation with amine catalysts, by Mr. Knoevenagel himself. Among the examples, the alkylamine catalyzed condensation of nitroethane with benzaldehyde (76%) and piperonal (80%) are described.

^{The Hive - Clandestine Chemists Without Borders}

sYnThOmAtIc
(Hive Addict)
05-14-04 05:52
No 507068
      Post 320904 06-13-02.

Post 320904 (Rhodium: "2,5-Dimethoxynitrostyrene w/ NaOH catalyst", Methods Discourse)06-13-02. Has been added to mdp2np.html on the archive site but not in the 02-26-04 zip? I know your busy and all and maybe it's on your list of things to do for your next archive zip? In case it has been overlooked, I just thought I should point it out seeing as two years have gone by laugh .

	https://the-hive.archive.erowid.org	the-hive@erowid.org



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	All 25 posts		Subject: Knoevenagel with various catalysts		Please login to post		Down


		Barium (Stranger) 06-11-02 15:08 No 319830				Knoevenagel with various catalysts (Rated as: excellent)
						As you can see there is great many catalysts which can be employed in the Knoevenagel-Walter. Benzaldehyde Nitroethane n-butylamine EtOH reflux 85% Ref 1 Benzaldehyde Nitroethane ethylenediamine 50 deg C 76% Ref 2 4-OH-benzaldehyde Nitromethane anilline 100 deg C 79% Ref 3 Piperonal Nitromethane ethylamine 8-10 deg C 97% Ref 4 Piperonal Nitroethane ethylamine 20 deg C 87% Ref 5 Piperonal Nitroethane n-pentylamine 20 deg C 87% Ref 5 Piperonal Nitroethane methylamine 20 deg C 87% Ref 5 3-MeO-benzaldehyde Nitroethane n-butylamine EtOH reflux 54% Ref 3 4-MeO-benzaldehyde Nitroethane ethylenediamine 80 deg C 100% Ref 2 4-MeO-benzaldehyde Nitropropane n-butylamine EtOH reflux 90% Ref 1 4-MeO-benzaldehyde 1-Nitrobutane n-butylamine EtOH reflux 90% Ref 1 3-OH-4-MeO-benzaldehyde Nitromethane methylamine 0-20 deg C 80% Ref 6 3-MeO-4-OH-benzaldehyde Nitromethane methylamine 20 deg C 81% Ref 6 3-MeO-4-OH-benzaldehyde Nitromethane ethylenediamine 20 deg C 95% Ref 2 3-MeO-4-OH-benzaldehyde Nitroethane methylamine 20 deg C 79% Ref 5 3-MeO-4,5-MDO-benzaldehyde Nitromethane n-pentylamine 20 deg C 90% Ref 8 3,5-diMeO-4-OH-benzaldehyde Nitromethane methylamine MeOH/20 deg C 97% Ref 9 3,5-diMeO-4-EtO-benzaldehyde Nitromethane NH4 acetate MeOH reflux 65% Ref 9 2,3,4,6-tetraMeO-benzaldehyde Nitromethane NH4 acetate MeOH reflux 93% Ref 10 Ref 1 J. Org. Chem., 15, 8 (1950) Ref 2 Zh. Prikl. Khim., 31, 663 (1958) Ref 3 J. Am. Chem. Soc., 74, 4489 (1952) Ref 4 J. Am. Chem. Soc., 73, 5556 (1951) Ref 5 JOC., 16, 221 (1951) Ref 6 J. Am. Chem. Soc., 72, 2781 (1950) Ref 7 JOC. 16, 221 (1951) Ref 8 J. Am. Chem. Soc., 71, 2211 (1949) Ref 9 J. Am. Chem. Soc., 76, 5556 (1954) Ref 10 JOC. 20, 104 (1955)



		Barium (Newbee) 06-11-02 15:25 No 319833				It´s not a beautiful thing but I don´t have the ...
						It´s not a beautiful thing but I don´t have the energy to edit it to look cute.. By the way...I´m now a newbee....



		Antoncho (Official Hive Translator) 06-11-02 16:40 No 319845				Interesting....
						.......but why there's no mention of dialkylammonium salts? Can they bee used as bases in this rxn? Can they not? Antoncho's asking 'cause there's some guy who isn't Antoncho who has a practical interest in this rxn using dimethylammonium acetate BTW, Barium, congratulations w/your new title! Keep up the good work Your posts are quite interesting to read, shall i say Antoncho



		Rhodium (Chief Bee) 06-11-02 16:44 No 319849				Yes, dialkylammoniums can also be used, there are ...
						Yes, dialkylammoniums can also be used, there are MANY possible catalysts out there. Are the aldimines true intermediates even in the one-pot syntheses, or does the amines simply act as a base?



		Barium (Newbee) 06-11-02 16:46 No 319850				I´ll bet
						Thanks Antoncho.. I´ve seen dimethylamine, diethylamine and triethylamine, as free bases and salts, be used as catalysts. Let´s see if I have some of the references nearby. I´ll post what I find.



		hypo (Hive Addict) 06-11-02 17:14 No 319856				Knoevenagel
						just for the record and the fse: it's Knoevenagel without 'h'.



		Rhodium (Chief Bee) 06-11-02 17:22 No 319858				What is this about Knoevenagel-Walther?
						What is this about Knoevenagel-Walter? I thought this specific case of a Knoevenagel reaction (RNO2 + RCHO) was called "Henry reaction".



		hypo (Hive Addict) 06-11-02 17:43 No 319861				google finds it all :)
						none of my oc books knows it under that name, but: https://www.rhodium.ws/chemistry/mda.dalcason.html: "If the appropriate piperonals are available to react with nitroethane, the Knoevenagel-Walter condensation, will permit the synthesis of ring-substituted analogs [24,29] through nitropropene intermediates (Fig. 5). "



		lugh (Moderator) 06-11-02 19:16 No 319881				Walter
						Walter co-authored Ber 37 4502 (1904) with Knoevenagel, in which it was first reported nitrostyrenes were obtained in good yield using amine catalysts



		Rhodium (Chief Bee) 06-11-02 19:24 No 319884				Aha - and the "Henry Reaction" reference is from ...
						Aha - and the "Henry Reaction" reference is from where?



		java (Newbee) 06-11-02 19:50 No 319891				re-Henry reaction
						Henry reaction;Kamlet reaction. L.Henry, Compt. rend. 120,1265 (18950; J. Kamlet, US. PAT. 2,151,517 (1939);C.A. 33,5003 (1939) Formation of nitroalcohols by an aldol-type condensation of nitroparaffins with aldehydes in the presence of base(Henry) or by the condensation of sodium salts of acinitroparaffins with the sodium bisulfite additon products of aldehydes in the presence of a trace of alkali or weak acid (Kamlet). widely used in the surar chemistry Ref. Merck Index 9th edition Organic Name reactions page 42[b]



		Boobsie (Stranger) 06-12-02 00:30 No 319979				Shulgin mentions performing this reaction on ...
						Shulgin mentions performing this reaction on piperonal with reactants in MeOH solution and aqueous NaOH as a base under the MDA entry, PiHKAL 100 http://www.erowid.org/library/books_online/pihkal/pihkal100.shtml Whether this would work well with other aldehydes is beyond me.



		Rhodium (Chief Bee) 06-12-02 01:27 No 320001				NaOH catalyzed condensation
						Here is a detailed description of such a procedure: https://www.rhodium.ws/chemistry/mdp2np.html



		Antibody2 (Rehabilitated) 06-13-02 01:34 No 320535				i like that one alot too Rhodium, any reason to ...
						i like that one alot too Rhodium, any reason to think it wouldn't work for nitromethane condensation as well?



		Rhodium (Chief Bee) 06-13-02 02:27 No 320554				nitrostyrene
						In Vogel's "Practical Organic Chemistry" 5th Ed. they use that method to make plain nitrostyrene, 3,4-methylenedioxynitrostyrene and 2,4-dimethoxynitrostyrene. If you want to I can OCR those two pages for you.



		Antibody2 (Rehabilitated) 06-13-02 02:59 No 320562				yes
						i'd appreciate that Rhodium! thanks



		Rhodium (Chief Bee) 06-13-02 03:22 No 320567				NITROSTYRENE (Rated as: excellent)
						Vogel's "Practical Organic Chemistry" 5th Ed.p 1035-1036 Experiment 6.136 NITROSTYRENE Ph-CHO + Me-NO2 -NaOH-> PhCH=CHNO2 Equip a 1500-ml three-necked flask with a thermometer, mechanical stirrer and a dropping funnel. Place 61 g (54 ml, 1 mol) of nitromethane (1), 106g (101 ml, 1 mol) of purified benzaldehyde and 200 ml of methanol in the flask and cool it with a mixture of ice and salt to about -10 °C. Dissolve 42g of sodium hydroxide in 40-50 ml of water, cool and dilute to 100 ml with ice and water; place this cold solution in the dropping funnel. Add the sodium hydroxide solution, with vigorous stirring, to the nitromethane mixture at such a rate that the temperature is held at 10-15 °C. Introduce the first few ml cautiously since, after a short induction period, the temperature may rise to 30°C or higher; check the rise in temperature, if necessary, by adding a little crushed ice to the reaction mixture. A bulky white precipitate forms; if the mixture becomes so thick that stirring is difficult, add about 10 ml of methanol. After standing for about 15 minutes, add 700 ml of ice-water containing crushed ice; the temperature should be below 5°C. Run the resulting cold solution immediately from a dropping funnel and with stirring into 500 ml of 4 M hydrochloric acid contained in a 3-litre flask; adjust the rate of addition so that the stream just fails to break into drops. A pale yellow crystalline precipitate separates almost as soon as the alkaline solution mixes with the acid. The solid settles to the bottom of the vessel when the stirrer is stopped. Decant most of the cloudy liquid layer, filter the residue by suction and wash it with water until free from chlorides. Transfer the solid to a beaker immersed in hot water; two layers form and on cooling again, the lower layer of nitrostyrene solidifies; pour off the upper water layer. Dissolve the crude nitrostyrene in 85 ml of hot ethanol. (CAUTION: nitrostyrene vapours are irritating to the nose and eyes, and the skin of the face is sensitive to the solid.) Filter through a hotwater funnel and cool until crystallisation is complete. The yield of pure nitrostyrene, m.p. 57-58°C, is 125 g (85%). Note 1: The commercial material may be redistilled and the fraction having b.p.100-102°C collected. Cognate preparations. 3,4-Methylenedioxy-nitrostyrene. In a 250-ml round-bottomed flask mix 30g (0.20 mol) of 3,4-methylenedioxybenzaldehyde (piperonal), 13.4 g (0.22 mol) of nitromethane, 7.8 g (0.1 mol) of ammonium acetate and 50 ml of glacial acid. Attach a reflux condenser, and boil the mixture under gentle reflux for 1 hour. Pour the reaction mixture with stirring into a large excess of ice-water (about 1 litre). When all the ice has melted, filter off the crude product under suction and recrystallise from a mixture of absolute ethanol and acetone (about 2:1 v/v). Almost pure yellow crystals of the nitrostyrene, m.p. 161 °C, are obtained. The yield is 23.3 g (60%). Further recrystallisation from the same solvent yields the pure compound, m.p. 162°C. 2,4-Dimethoxy-m-nitrostyrene. Follow the above procedure, but use 33.2g (0.20 mol) of 2,4-dimethoxybenzaldehyde as the starting material. The yield of recrystallised product (yellow crystals, m.p. 103°C) is 28.5 g (68%). Further recrystallisation gives pure product of m.p. 105°C.



		Rhodium (Chief Bee) 06-13-02 22:16 No 320904				2,5-Dimethoxynitrostyrene w/ NaOH catalyst (Rated as: excellent)
						2,5-Dimethoxynitrostyrene JOC 52, 2945-2947 (1987) A mixture of 2,5-dimethoxybenzaldehyde (1.97 g, 11.8 mmol) and nitromethane (0.72 g, 11.8 mmol) in methanol (200 mL) was stirred at room temperature until the solids dissolved. The solution was cooled to 0°C and a 10.5 M NaOH solution (2 mL) was added dropwise over 20 min. The alkaline solution was added slowly to a 4% HCl solution (200 mL) maintained at 60°C. The pale yellow amorphous solid that formed was filtered and washed with water (200 mL). The crude product was recrystallized from absolute ethanol to give yellow needles (2.11 g, 85%). mp 121-123°C; IR 3100, 1620, 1500, 1351 cm^-1; ¹H NMR (CDCl₃) δ 7.9 (dd, J=14 Hz, 2 H), 6.88 (d, J=3 Hz, 3 H), 3.85 (s, 3 H), and 3.75 (s, 3 H). Preparation of 10.5 M NaOH: Dissolve 10.5g sodium hydroxide under cooling in 20ml water, and after cooling dilute the solution to exactly 25ml.



		Sunlight (Pioneer Researcher) 06-14-02 21:02 No 321361				Good
						It is fucking good !!! mmm, well the volumes are big.



		Bwiti (PVC-Analog Taste-Tester) 06-15-02 19:42 No 321793				Isopropylamine in methanol works great for ...
						Isopropylamine in methanol works great for nitroethane/benzaldehyde. Love my country, fear my government.



		Boobsie (Stranger) 06-16-02 21:58 No 322208				SWIM is thinking that this could easily lead to a ...
						SWIM is thinking that this could easily lead to a one-pot synth of 2C-H, using the Zn/HCl reduction posted by Sunlight, taking advantage of the fact that the yields are pretty high and the nitrostyrene will already be in an acidic medium that would only need be further acidified for the reduction step. SWIM doesn't know how this could affect yields (probably negatively), and given the ease of filtering everything and moving to a different flask it probably isn't worth it.



		Rhodium (Chief Bee) 06-16-02 22:31 No 322213				Bad idea. Always isolate your reaction ...
						Bad idea. Always isolate your reaction intermediates to remove by-products.



		Aurelius (Hive Bee) 06-17-02 19:55 No 322491				nitroethane
						Hey Bwiti, did you use the nitroethane source aurelius sent you? just curious. and you didn't tell aurelius you've done nitropropenes, email the details.



		Rhodium (Chief Bee) 05-13-04 23:50 No 506995				Knoevenagel's first Nitrostyrene article (Rated as: good read)
						Condensation aliphatischer Nitrokörper mit aromatischen Aldehyden durch organische Basen E. Knoevenagel & L. Walter Chem. Ber. 37, 4502-4510 (1904) (https://www.rhodium.ws/pdf/knoevenagel.condensation.pdf) The first article on nitroalkene preparation with amine catalysts, by Mr. Knoevenagel himself. Among the examples, the alkylamine catalyzed condensation of nitroethane with benzaldehyde (76%) and piperonal (80%) are described. ^{The Hive - Clandestine Chemists Without Borders}



		sYnThOmAtIc (Hive Addict) 05-14-04 05:52 No 507068				Post 320904 06-13-02.
						Post 320904 (Rhodium: "2,5-Dimethoxynitrostyrene w/ NaOH catalyst", Methods Discourse)06-13-02. Has been added to mdp2np.html on the archive site but not in the 02-26-04 zip? I know your busy and all and maybe it's on your list of things to do for your next archive zip? In case it has been overlooked, I just thought I should point it out seeing as two years have gone by .

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