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Novel Discourse / Re: Electrochemical Reduction of Nitrostyrenes
« Last post by P2PA on March 26, 2017, 07:26:32 AM »
its a long time ago but I think its still an interesting thread.

Anyone who is more experienced with this reduction method?

I´ve some questions:

1. What materials can be successfully used as cell divider instant of the flower pot?

2. Pre coated (PbO2) lead electrodes are the way to go?

3. Is it necessary, that all of the substrate is solved at once or just before being reduced?

Chemicals & Equipment / Re: Supercritical CO2 extraction
« Last post by aniracetam on March 17, 2017, 01:39:01 PM »
parts list:

(all brass or stainless steel, except storage tank, and all rated for 3000psi, unless specified)

CO2 storage cylinder
1 10lb aluminum CO2 tank, rated @1800psi
1 CGA-320 cap and stem, with nylon disc (usually included)

3 Swagelok QF-4-S-4PF, quick connect stems, one connects to CGA-320 stem on storage tank, other two connect to needle valves on the sample cylinder

Sample Cylinder
1 Swagelok Whitey 1000CC sample cylinder, with two 1/4" FNPT ends, rated for 1800psi
2 Swagelok 1/4" MNPT needle valves, rated for 6000psi
400mesh SS screen, cut a small piece to stuff in needle valve on sample cylinder outlet

transfer hose assembly
2 Swagelok SS-QF4-B-4PF
2 Swagelok tees 1/4" FNPT
1 3000psi oil-filled pressure gauge, 1/4" MNPT
1 60" stainless steel braided, PTFE-lined hose with 1/4" MNPT ends
2 Swagelok needle valves, 1/4" MNPT, rated for 6000psi, one connects to tee connecting to sample cylinder, facing out..this will be for bleeding backpressure, to disconnect the transfer line
2  1/4" MNPT unions
1  1/4"  hex FNPT union

collection vessel, low pressure

3" x 12" sanitary stainless steel spool
1 3" triclover endcap
1 3" triclover endcap with two 1/4" FNPT inlets, or one with 1/2" (then also get a 1/2" to 1/4" FNPT bushing)
2 3" viton gaskets
2 3" triclover clamps
(connects to collection vessel inlet) 1 Swagelok QF-4-S-4PM
1 1/4" MNPT pressure relief valve, 140 psi

heating assembly
1 silicone heating pad, Omega part# SSHB-1224-720-120
1 PID temp controller, Mypin TA-4, with thermocouple
1 20A relay

note: remember to wrap PTFE tape around all brass-brass/brass-ss/ss-ss connections, 3 rounds. hand tighten connections as much as possible, mark across the connection with a permanent marker, then wrench tighten 1 1/4 turns (for 1/4" NPT connections, as specified by Swagelok).

the nice thing about this sort of setup is its modularity. one could swap out sample cylinders as needed. I also have a 1L Hoke cylinder rated for 5000psi operating pressure.
Chemicals & Equipment / Re: Supercritical CO2 extraction
« Last post by aniracetam on March 17, 2017, 01:24:25 PM »
I assembled that extractor for >$700, not incl. the rolling island. it is an open loop system.
it is primarily Swagelok parts, 1/4" NPT. the sample cylinder is 1L, rated for 1800psi, but can easily handle 3000. the hoses are rated for 3000. needle valves are rated for 6000. The collection vessel is 316 sanitary stainless with a 150psi pressure relief valve. the silicone heating mat is rated for 750W. operating parameters for a typical run have been 1450-1600 psi @ 55C, temp monitored by thermocouple.

some notes about SC-CO2: it is primarily effective on nonpolar compounds, with m.w. up to 400. polar entrainers such as ethanol may be used to increase the effectiveness of pulling more polar compounds. It is advantageous to soxhlet for pulling nonpolar to somewhat polar compounds, as run times are typically 1-3 hrs, and it can extract thermolabile compounds to good effect. SC-CO2 has similar polarity to hexanes. all material should be dry as possible, as residual water freezes in the needle valves when they are opened, causing backpressure. this is caused by the joule-thompson effect.

I have used it to extract a variety of oils and extracts from star jasmine, lavender, pecans, 75 dried ghost peppers, cinnamon, cocoa, blueberries, vanilla, strawberries, apricots, guava, dill, lemon peel, mint, honeydew, coconut, banana, honeysuckle, and peach.
Chemicals & Equipment / Re: Supercritical CO2 extraction
« Last post by hamsterbob on March 17, 2017, 10:48:06 AM »
I want a mr extractor!
Chemicals & Equipment / Re: Supercritical CO2 extraction
« Last post by Halogen on March 17, 2017, 10:32:29 AM »
Chemicals & Equipment / Re: Supercritical CO2 extraction
« Last post by aniracetam on March 17, 2017, 04:03:43 AM »
holy necroposting, batman..
Publications / Re: Benzaldehyde Synthesis - Douchermann
« Last post by byko3y on March 17, 2017, 02:12:37 AM »
There's a lot of routes to convert alkyl halide to aldehyde. In fact, first step of kornblum oxidation is formation of alkyl halide form alcohol.
Hass-Bender reaction[1],  the Sommelet reaction[2],  the Krohnke reaction[3],  the Kornblum reaction[4],  the Masaki photooxidation[5],  and oxidations using NaOCl[6],  MnO2[7], KNO3[8], DMSO[9],  Pyridine N-Oxide in the presence of Ag2O[10], and transition metal complexes[11],  green oxidation of benzyl halides with V2O5-H2O2 [12] .
1. (a) Hass, H. B.; Bender, M. L. The reaction of benzyl halides with the sodium salt of 2-nitropropane: A general synthesis of substituted benzaldehydes. J. Am. Chem. Soc. 1949, 71, 1767–1769; (b) Klanderman, B. H. Aldehyde synthesis: A study of the preparation of 9,10-anthracene-dicarbox aldehyde and other aromatic dialdehydes. J. Org. Chem. 1966, 31, 2618–2620; (c) Klein, T. A.; Schkeryantz, M. S. Tandem Hass–Bender-Henry reaction for the synthesis of dimethylnitro alcohols from benzylic halides. Tetrahedron Lett. 2005, 46, 4535–4538.
2. Larock, R. C. Comprehensive Organic Transformation; John Wiley: New York, 1999; vol. 2.
3. Nishimura, T.; Onoue, T.; Ohe, K.; Uemura, S. Palladium(II)-catalyzed oxidation of alcohols to aldehydes and ketones by molecular oxygen. J. Org. Chem. 1999, 64, 6750–6754.
4. Kornblum, N.; Jones, W. J.; Anderson, G. J. A new and selective method of oxidation: The conversion of alkyl halides and alkyl tosylates to aldehydes. J. Am.. Chem. Soc.
1959, 81, 4113–4114.
5. Akichika, I.; Tomohiro, K.; Shinji, I.; Masaki, Y. Photooxidation of arylmethyl bromides with mesoporous silica FSM-16. Org. Lett. 2000, 16, 2455–2457.
6. Khurana, J. M.; Sahoo, P. K.; Titue, S. S. Ultrasound assisted oxidation of benzylic halides with sodium hypochlorite. Synth. Commun. 1990, 20, 1357–1361. 18 P.
7. (a) Goswami, S.; Jana, S.; Dey, S. A simple and convenient manganese dioxide oxidation of benzyl halides to aromatic aldehydes under neutral condition. ChemInform 2006, 36, 28–31; (b) Goswami, S.; Jana, S.; Dey, S.; Adak, A. K. A simple and convenient manganese dioxide oxidation of benzyl halides to aromatic aldehydes under neutral condition. Chem. Lett. 2005, 34(2), 194–195.
8. Liu, Q. F.; Lu, M.; Sun, F.; Li, J.; Zhao, Y. B. Oxidation of benzyl halides to aldehydes and ketones with potassium nitrate catalyzed by phase-transfer catalyst in aqueous media. Synth. Commun. 2008, 38, 4188–4197.
9. (a) Climent, M. S.; Marinas, J. M.; Sinisterra, J. V. Ba(OH)2 catalyst in organic reactions, XIII. Oxidation of benzyl halides to benzaldehydes. React. Kinet. Catal. Lett. 1987, 34(1), 201–206; (b) Bratulescu, G. Synthesis of aromatic aldehydes by a fast method involving Kornblum’s reaction. Synth. Commun. 2008, 38, 2748–2752; (c) Kshirsagar, S. W.; Patil, N. R.; Samant, S. D. Mg–Al hydrotalcites as the first heterogeneous basic catalysts for the Kornblum oxidation of benzyl halides to benzaldehydes using DMSO. Tetrahedron Lett. 2008, 49, 1160–1162.
10. Chen, D. X.; HO, C. M.; Wu, Q. Y. R.; Wu, P. R.; Wang, F. M.; Wu, W. M. Convenient oxidation of benzylic and allylic halides to aldehydes and ketones. Tetrahedron Lett. 2008, 49, 4147–4148.
11. (a) Griffith, W. P.; Jolliffe, J. M.; Ley, S. V.; Williams, D. J. A new ruthenium(VI) oxidant: Preparation, X-ray crystal structure, and properties of (Ph 4 P)[RuO 2 (OAc)Cl 2 ]. J. Chem. Soc., Chem. Commun. 1990, 18, 1219–1221; (b) Peyman, S.; Irai, M-B. Tetrakis (pyridine)silver(II)peroxodisulfate, [Ag(py) 4 ]S 2 O 8 , a reagent for the oxidative transformations. Bull. Chem. Soc. Jpn. 1992, 65, 2878–2880; (c) Bressan, M.; Forti, L. Ruthenium-catalyzed oxidation of alkylaromatics by monopersulfate with preferential oxidative fission of the benzene ring. J. Mol. Catal. 1993, 84, 51–58.
12. Li, C. B.; Zheng, P. W.; Li, J.; Zhang, H., Cui, Y.; Shao, Q. Y.; Ji, X. J.; Zhang, J.; Zhao, P. Y.; Xu, Y. L. The dual roles of oxo diper oxo-vanadate both as a nucleophile and an oxidant in the green oxidation of benzyl alcohols or benzyl halides to aldehydes and ketones. Angew. Chem. Int. Ed. 2003, 42, 5063–5066.
Have fun.
Publications / Re: Benzaldehyde Synthesis - Douchermann
« Last post by Halogen on March 17, 2017, 12:20:34 AM »
what about benzyl bromide as a sommelet reaction precursor? i know it's theoreticaly possible, but what about practice? ever tried it instead of benzyl chloride?
Publications / Re: ketones and stuff
« Last post by carl_nnabis on March 16, 2017, 11:00:17 PM »
Well I wouldn´t call that stalker who´s putting random chemical notes in my life a friend, but yeah, there was really a little bit of information about this attempt(incomplete though).

It says 11mmol of Isonitrosoketone and 67mmol of Na were used, an amine-like odour was noticed during the reaction, but no mention of product obtained if any at all(I don´t think so).
I assume, since the reduction of this nitrosoketone is described as hard to achieve(compared to other oximes), that he failed.

A literature source describing the complete reduction, using catalytic hydrogenation, mentions the presence of HCl as being vital for success.
Lead me to theorise that the formation of a pyrazine, a dimer is probably a competing reaction in the basic milieu of a Na/EtOH reduction, whereas the cathinone formed as intermediate dimerises to said pyrazine.

This is also the reason why I assume an Al/Hg reduction(acidic, with AcOH) is a better choice.
Probably even better would be, to do it in two steps, reducing the carbonyl to an alcohol first with borohydride.
Publications / Re: ketones and stuff
« Last post by bsmathers on March 15, 2017, 11:39:38 PM »
Did your Bulgarian friend also happen to leave a writeup of the attempted sodium reduction?  ;D

I have a hard time believing that an amalgam reduction would work better than an alkali metal one, considering the problem in my mind is incomplete reduction. Then again, I have been wrong before...

I wonder if lithium would be a worthwhile thing to try?
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