Grease is the word

An intriguing post was made on the subreddit chempros; some difficulties with Grease contamination. If I recall correctly, the team here at Yonsung also had such problems; they utilized a MeCN/Heptane work-up, to force the grease into the heptane layer.

However, here's a different (yet related) trick:

I got you on this one! No idea where this crap comes from, always an issue on small scale. But there's an easy fix. Grease is insoluble in acetonitrile! 😎 So just concentrate your product down, add a small amount of acetonitrile and mix. You'll see the grease crash out like little droplets of fat. Then filter through a syringe filter and concentrate down again and then you'll have a grease-free product! You can go ultra-lazy and just add deuterated acetonitrile to the sample and filter, then just NMR. Either way, your greasy problems will be a thing of the past 👍 Lemme know how it works out for you.

Indeed!

 

Reduction of Nitroarenes

Recently, we faced the challenge of reducing an aromatic nitro group to an aniline. Typically, this transformation necessitates the use of Pd/C hydrogenation conditions, which in turn require (for this case) a pressurized reactor—a requirement we were keen to circumvent. In pursuit of optimal conditions, our search led us to an unexpectedly classical solution: the use of Fe/HCl (aqueous). The efficiency of this method came as a pleasant surprise, given how classical this reaction is.

Nevertheless, before experimenting, I conducted a (un)comprehensive literature review. The result I will post here for your and my future reference; a list of papers dealing with reduction of nitroarenes; but it does go without saying, the reduction of nitroarenes is arguably one of the most extensively investigated reactions in the field of process chemistry.

Citation (Year Journal Page)	Conditions	Type
2015 RSC Adv. 8391		Review
2023 J. Chem. Edu 3171		Review
2018 OPRD 430		Review
2018 J. Chem. Chem. Eng. 74		Review
1996 Chem.Rev. 2035		Review
1952 Ind. Eng. Chem. 1980		Review
2023 ACS Cent. Sci. 836	Pd/C or Rh/C or Pt/C + H2	Metal + Hydrogenation
2024 OPRD 577	Pt3%/V2%/C, EtOH, H2, rt	Metal + Hydrogenation
2003 Synthesis 1657	ZnBr2, Pd/C, H2	Metal + Hydrogenation
2018 EJOC 3416	CoSO4.NaBH4 reduction	Borohydride type
2023 OL 8787	KBH4.I2 reduction [BI3]	Borohydride type
2016 Int.J.Org.Chem.	NaBH4, AcOH, PdC	Borohydride type
2022 JOC 910	B2[OH]4. 4,4'bipyridine	Boron type
2021 Org.Chem.Front. 4554	KOtBu.BEt3.Hbpin	Boron type
2020 AIP.Conf.Proc. 2280	BF3OEt2 reduction	Lewis Acid type
2019 OL 9812	B2nep2	Boron type
2019 OL 2194	B2(OH)4 reduction	Boron type
2017 TET 3898	H2O, PdC, B2[OH]4	Boron type
2017 Chem.Select 5214	Aminothiophenol, MW	-
US2003/78249	NaBH4, NiCl2, MeOH	Borohydride type

Citation (Year Journal Page)	Conditions	Type
2020 EJOC 1853	Sulfur reduction	Sulfur type
2020 Can.J.Chem.444	Human Hair reduction	-
2006 TL 9095	Sulfur reduction	-
2001 TL 5601	Hydroiodic acid reduction	-
1982 TL 147	Hydrazine, Raney Nickel	-
1945 J. Chem. Soc. 202	Fe, Fe2SO4, H2O, 100 °C	ANCIENT
2007 Synlett 2602	Fe, HCl, EtOH/H2O	ANCIENT
2021 AJOC 583	KOH, iPrOH	Base
WO2014/161976	Fe, AcOH	ANCIENT
1984 TL 839	SnCl2, EtOH	ANCIENT
2010 R.Commun.M.S.1105	Zn, AcOH	ANCIENT
JP2015/528022	Zn, NH4Cl, MeOH	ANCIENT

Check out that 2020 Can. J. Chem. 444 paper; reduction of nitroarenes via human hair.