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Vol.3, No.1
Phosphazene
Bases
Verkade`s
Superbases
Amine based
traditional bases
Lithium based
traditional bases
Potassium based
traditional bases
Strong and Hindered Bases
in Organic Synthesis
Strong and Hindered Bases in Organic Synthesis
Bases are a very important class of reagents for synthetic organic chemistry, as in a large amount of
reactions the activation of starting materials or reagents through deprotonation is a first step in the
synthesis towards new molecules. As different applications and reaction conditions require the use of a
specific base, a broad range of inorganic, organic and organometallic bases have been developed and are
routinely used. These bases are differentiated by strength, nucleophilicity, steric hindrance or solubility.
Special efforts have been invested in optimizing the basicity and in reducing the nucleophilicity of
organic bases. These efforts have resulted in several families of interesting molecules.
Fluka and Aldrich are obliged to offer you a broad scope of organic bases, from the more “specialised
ones”, such as the posphazene- and the Verkade`s bases, to the more “traditional” ones, such as alkyl- or
aryllithium. The first two classes of exclusive bases are especially suitable for synthetic problems where
fine tuning the basicity and the selective sterical hindrance is the key-factor to achieve the best results.
Themes discussed in this ChemFile are:
Phosphazene bases, subdivided into
N Monomeric phosphazene bases (P1)
N Dimeric phosphazene bases (P2)
N Tetrameric phosphazene bases (P4)
Verkade’s bases
Traditional bases, subdivided into
N amine based traditional bases
N lithium based traditional bases
N potassium based traditional bases
Sigma-Aldrich offers you ALL the bases you need for your synthetic work from a single source!
Fluka and Aldrich are proud to offer you a wide range of bases, starting from the “traditional ones”, such as MeLi or nBuLi, up to the most “specialized ones”, such as Fluka`s TOP EXCLUSIVE phosphazene bases or the Verkade`s bases
exclusively from Aldrich.
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Front picture presents a phosphazene base in space, made by Armand Tepper
Acknowledgement: We would kindly like to thank Prof. Dr. R Schwesinger, Institute for Organic Chemistry and Biochemistry,
University of Freiburg, Germany, for his contributions to this chemfile on phosphazene bases
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whole series of chemfiles as free-to-download pdf files.
Phosphazene Bases Introduction
Phosphazene bases are extremely strong and uncharged bases, built on a unit where a nitrogen basic center is double
bonded to pentavalent phosphorus.[1,2] Through oligomerization of the peralkylated triaminoiminophosphorane unit, the
basicity improves dramatically (Figure 1). In the case of the monomeric phosphazene base, its basicity is about a 2-3
units beyond the basicity range of DBU (MeCNpKBH+ 24.3) and DBN, but reaches a MeCNpKBH+ of over 40 in the case of a
tetrameric P4 phosphazene base (DBU = 1,8-Diazabicyclo[5.4.0]undec-7-ene, DBN = 1,5-Diazabicyclo- [4.3.0]non-5-ene).
Fluka offers these reagents as monomeric (P1 and BEMP), dimeric (P2), and tetrameric (P4) bases, with different side chains
to control their sterical hindrance. Scheme 1 shows the basicity of phosphazene bases compared to other bases (in the
absolute acetonitrile scale), as well as compared to the acidity of important organic compounds or classes of compounds.
Figure 1
Properties of Phosphazene Bases:
N
N
N
N
N
High solubility in apolar to moderately polar solvents (e.g. hexane, toluene or THF)
Very strong solubilizing effects in appropriate weakly acidic compounds
Remarkably stable towards electrophilic attack, O2 and hydrolysis.
Depending on their base strength, slightly to extremely hygroscopic
Large sterical hindrance, depending on the type of side chain
Applications of Phosphazene Bases:
N
N
N
N
In situ generation of highly reactive „naked“ anions, e.g. for alkylation reactions or for spectroscopic investigations.
Applicable in reactions where ionic bases cause solubility problems.
Applicable in reactions where ionic bases are sensitive towards oxidation or acylation.
Applicable in reactions where ionic bases result in Lewis-acid catalyzed side reactions (e.g. in aldol reactions,
epoxide-opening, hydride shifts, elimination of alkoxide, polyanion-formation).
Benefits of using Phosphazene Bases:
N Easier work-up through cleaner reactions.
N Close to quantitative recovery.
N Reaction rate enhancement.
References: [1] Paquette, L. A., “Encyclopedia of Reagents for Organic Synthesis”, Wiley, 1995, Vol. 6, 4110. [2] Schwesinger, R. et al., Liebigs Ann. 1996, 1055. [3]
Schwesinger, R. et al., Chem. Ber. 1994, 127, 2435.
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Fluka Product number 79421: “REAGENT OF THE YEAR 1992”
Prof. Dr. Schwesinger obtained in 1992 the Fluka Prize “Reagent
of the Year” with his product 79421 (Phosphazene Base P4-t-Bu).
R. Schwesinger, born 1947, studied at the University of Freiburg,
Germany, where he obtained his PhD under direction of Prof. Dr.
H. Prinzbach. In 1978 he joined the group of Prof. Dr. A.
Eschenmoser at the ETH Zürich as a postdoctoral fellow until 1980. He returned to Freiburg
and became “Dozent” in 1990. From 1987 - 1998, the Fluka Prize “Reagent of the Year” has
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reagent of prime importance, useful in organic chemistry, biochemistry or analytical chemistry.
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Scheme 1
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Monomeric Phosphazene Bases (P1 bases)
Fluka offers four monomeric phosphazene bases P1, i.e. 79412, 20025, 79408 and 79432, who differ with respect to
their steric hindrance and basicity (Table 1).
Table 1. Order of Basicity of P1 Bases
Order of steric hindrance:
P1-t-Oct >
BEMP >
P1-t-Bu >
BTPP
Fluka Product Number:
79412
20025
79408
79432
Basicity (MeCNpKBH+):
26.5
27.6
26.9
28.4
79408
79432
20025
79412
20026
All four P1 bases mentioned in Table 1 are distillable liquids and can be easily handled with syringe techniques. Regarding
many favorable features they resemble DBU. However, in comparison to DBU (MeCNpKBH+ = 24.3) they are less nucleophilic,
far less sensitive towards hydrolysis and 2-4 orders of magnitude more basic.[1] Furthermore, they are particularly suitable
for deprotonation (activation) of pronucleophiles. The P1 bases have become important tools e.g. in the field of nucleic
acid chemistry,[2,3,4,5] amino acid[6] or peptide synthesis,[7-11] and solid phase chemistry.[12,13] See Table 2 for a list of our P1
bases with their properties, package size etc.
Do you require Phosphazene Bases on a larger scale?
Or do you have other large-scale projects you want to out-source?
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Monomeric Phosphazene Bases (P1 bases)
Table 2. Phospazene bases P1
79408
Phosphazene base P1-t-Bu
N’-tert-Butyl-N,N,N’,N’,N’’,N’’-hexamethylphosphorimidic triamide
tert-Butylimino-tris(dimethylamino)phosphorane
purum, ≥98.0% (NT)
C10H27N4P
Mr 234.3
[81675-81-2]
5 ml , 25 ml
79432
Phosphazene base P1-t-Bu-tris(tetramethylene)
BTPP, tert-Butylimino-tri(pyrrolidino)phosphorane
purum, ≥97.0% (NT)
C16H33N4P
Mr 312.4
[161118-67-8]
5 ml, 25 ml
Phosphazene base P1-t-Oct
tert-Octylimino-tris(dimethylamino)phosphorane
purum, ≥98.0% (NT)
C14H35N4P
Mr 290.4
[161118-69-0]
1 ml, 5 ml
79412
20025
2-tert-Butylimino-2-diethylamino-1,3-dimethyl-perhydro-1,3,2 diazaphosphorine
BEMP
Mr 274.4
[98015-45-3]
5 ml, 25 ml
purum, ≥98.0% (GC)
C13H31N4P
20026
2-tert-Butylimino-2-diethylamino-1,3-dimethyl-perhydro-1,3,2-diazaphosphorine
on polystyrene
BEMP on polystyrene, capacity base ~2.2 mmol/g
5 g, 25 g
Especially interesting for solution phase synthesis and high-throughput chemistry is Merrifield-resin-bound BEMP 20026
(2-tert-Butylimino-2-diethylamino-1,3-dimethyl-perhydro-1,3,2-diazaphosphorine). This base combines the ease of use,
separation and recovery of a supported reagent with the outstanding features of BEMP as a base. It is used successfully as
a strong and anhydrous base for synthesis with polymeric reagents[17-25] in parallel synthesis.[1]
Applications. The P1 phosphazene bases have a broad application area in organic synthesis. They can be used for
alkylation-,[2-6,8-11,13-15,18-27] michael-addition-,[7,12,16,28,29] ester saponification-,[25] acylation-,[30,31] silylations,[32] aldol-condensation[33]
and heterocumulene reactions,[34] as well as in reactions involving transition metals.[35,36] Occasionally, the P1 bases are
suitable for E2-eliminations.[17] Among the successfully converted substrates are alcohols,[2,3,25] phenols,[15] thiols,[26,34,35] NHacidic heterocycles,[2,4,5,14,18,23,24,25] amines,[20,22,30] hydrazones,[21] hydrazids,[34] amides,[36] sulfonamides,[19] malonic esters,[2]
benzophenone imines of glycine esters,[6,7,8,13] imides,[9] acetoacetic ester,[16] α-phenylsulfinyl esters,[27] cyano-[12] and
isocyanoacetic esters.[11,28,29] Acrylic esters,[27] N-arylamides,[36] dihydrobenzofuranes,[15] pyrroles[28], pyrazoles,[21] 3-thio-1,2,4triazoles,[34] isoindoles,[29] glycosides[2,26] nucleoside analogues,[4,5,24] and epibatidine[20] have thus been efficiently synthesized.
References: [1] Schwesinger, R. et al., Chem. Ber. 1994, 127, 2435. [2] Schwesinger, R., Chimia 1985, 39, 269. [3] Beijer, B. et al., Nucleic Acid Res. 1990, 18, 41; Kachalova,
A. V. et al., Nucleos. Nucleot. Nucl. 2000, 19, 1693. [4] Knapp, S., Gore, V. K., Organic Lett. 2000, 2, 1391. [5] Lukin, K. A. et al., Nucleos. Nucleot. Nucl. 2000, 19, 815. [6]
O´Donnell, M. J. et al., Tetrahedron Lett. 1998, 39, 8775. [7] O´Donnell, M. J. et al., Tetrahedron Asymm. 2001, 12, 82. [8] Scott, W. L., O´Donnell, M. J. et al., J. Org. Chem.
2002, 67, 2960. [9] Guillena, G., Nájera, C., Tetrahedron Asymm. 1998, 3935. [10] Nájera, C. et al., Synthesis 1999, 704. [11] Kotha, S. et al., Bioorg. & Med. Chem. Lett.
2002, 12, 1113. [12] Paulitz, C., Steglich, W., J. Org. Chem. 1997, 62, 8474. [13] O´Donnell, M. J., Aldrichim. Acta 2001, 34, 3. [14] Heinelt, U. et al., Bioorg. & Med. Chem.
Lett. 2001, 11, 227. [15] Berteina, S., De Mesmaeker, A., Tetrahedron Lett. 1998, 39, 5759; Du, X., Armstrong, R. W., J. Org. Chem. 1997, 62, 5678. [16] Jung, G. et al., J.
Org. Chem. 1999, 64, 1362. [17] García-Ochoa, S. et al., Tetrahedron Lett. 2001, 42, 6675. [18] ] Xu, W. et al., Bioorg. & Med. Chem. Lett. 1998, 8, 1089. [19] Ley, S. V. et
al., Bioorg.& Med. Chem. Lett. 1999, 9, 2049. [20] Ley, S. V. et al., J. Chem. Soc., Perkin Trans. 1 1999, 1253. [21] Ley, S. V. et al., Bioorg. & Med. Chem. Lett. 2000, 10, 1983.
[22] Ley, S. V., Massi, A., J. Chem. Soc., Perkin Trans. 1 2000, 3645. [23] Ley, S. V. et al., J. Chem. Soc., Perkin Trans. 1 1999, 107. [24] Kim, K. et al., Tetrahedron Lett. 2000,
41, 3573. [25] Schwesinger, R., Nachr. Chem. Tech. Lab. 1990, 38, 1214. [26] Koh, J. T. et al. Carbohydr. Res. 2000, 325, 169. [27] T. Allmendinger, Tetrahedron 1991, 47,
4905. [28] Uno, H. et al., Synthesis 1999, 471. [29] Murashima, T., Ono, N. et al., J. Chem. Soc., Perkin Trans. 1 2000, 995; 471; Lash, T. D. et al., Synlett. 2000, 213; Lash,
T. D., Gandhi, V., J. Org. Chem. 2000, 65, 8020. [30] Kim, K., Le, K., Synlett. 1999, 1957. [31] Prinzbach, H. et al., Chem. Ber. 1992, 125, 1719. [32] Prinzbach, H. et al.,
Angew. Chem. Int Ed. Engl. 1989, 28, 298 . [33] Montforts, F. P., Schwartz, U. M., Liebigs Ann. Chem. 1991, 709. [34] Graybill, T. L. et al., Tetrahedron Lett. 2002, 43, 53055309. [35] Jaun, B. et al., Chem. Eur. J. 2000, 6, 3508. [36] Buchwald, S. L. et al., J. Am. Chem. Soc. 2002, 124, 7421.
For questions about the pricing or to order: call your local Sigma-Aldrich Office
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Dimeric Phosphazene Bases (P2)
Fluka lists two P2 phosphazene bases (79416 and 79417), which differ with respect to their steric hindrance and basicity
(Table 3).
Table 3. Order of Basicity of P2 Bases
Order of steric hindrance:
P2-t-Bu
>>
P2-t-Et
Fluka Product Number:
79416
79417
Basicity (MeCNpKBH+):
33.5
32.9
The phosphazene base P2-t-Bu is a solid at room temperature (m.p. 76 ºC). and is available as a 2 M solution in THF
(79416). P2-Et 79417 is offered as a stable, distillable liquid, which can easily be handled with syringe techniques. Both
exhibit characteristics similar to those of DBU, but compared to DBU they are more hindered, much less sensitive towards
hydrolysis, and 8.5-9 orders of magnitude more basic[2,3] See Table 4 for a list of our P2 bases with their properties, package
size etc.
79417
79416
Applications: P2-Et 79417 is particularly suitable for E2-eliminations[3,4,5,6] being around 4 orders of magnitude more
reactive than DBU. Deprotonations for spectroscopic investigations,[1] double bond shifts in vinyl sulfones,[7] and alkyllithium activation[8] have also been reported. The P2-t-Bu 79416 is particularly suitable for deprotonation (activation) of
pronucleophiles. The P2 bases have attracted interest in the field of anionic polymerisation[8,9] and have been reported to
support alkylation-,[10,11,12,13] michael addition-,[13,14] aldol condensation-,[13,15,16] and copper-induced coupling reactions.[17]
Among the successfully converted low acidic substrates are alcohols,[10] phenols,[5] carbamates,[11] NH-acidic heterocycles,[6]
phosphines,[12] benzyl sulfones,[13] glycin ester Schiff-bases,[14,15] α-azidoketones,[18] and N-alkylpyridinium salts.[3] Cinnamic
esters,[13] chiral phenyloxiranes,[16] chiral amino acids,[14,15] biaryl thioethers,[17] and pyrazines[18] are thus efficiently
synthesized.
Table 4. Phospazene bases P2
79416
Phosphazene base P2-t-Bu solution
1-tert-Butyl-2,2,4,4,4-pentakis(dimethylamino)-2Λ5,4Λ5-catenadi(phosphazene)
purum, ~2.0 M in THF
C14H39N7P2 Mr 367.5 [111324-03-9] 1 ml, 5 ml, 25 ml
79417
Phosphazene base P2-Et
1-Ethyl-2,2,4,4,4-pentakis(dimethylamino)-2Λ5,4Λ5-catenadi(phosphazene)
purum, ≥98.0% (NT)
C12H35N7P2 Mr 339.4 [165535-45-5] 1 ml, 5 ml
References: [1] Schwesinger, R. et al., Liebigs Ann. 1996, 1055. [2] Angelaud, R., Landais, Y., Tetrahedron Lett. 1997, 38, 8841. [3] Dega-Szafran, Z. et al., J. Phys. Org. Chem.
1999, 12, 39. [4] Prinzbach, H. et al., Tetrahedron Lett. 1987, 28, 2517. [5] Zundel, G. et al., J. Phys. Chem. 1996, 100, 9021; Sobczyk, L. et al., J. Chem. Res. (S) 1997, 151.
[6] Zundel, G. et al., J. Mol. Struct. 1997, 436, 103; Bauer, R., Zundel, G., J. Phys. Chem. A 2002, 106, 5828. [7] Fuchs, P. L. et al., Tetrahedron Lett. 1996, 37, 5249; Fuchs, P.
L. et al., Tetrahedron Lett. 1997, 38, 2601. [8] Möller, M. et al., Macromol. Symp. 1996 (Intern. Symposium on Ionic Polymerization 1995), 331; Molenberg, A., Möller, M.,
Macromol. Chem. Phys. 1997, 198, 717. [9] Memeger Jr., W. et al., Macromolecules 1996, 29, 6475, 8568. [10] Schwesinger, R., Nachr. Chem. Tech. Lab. 1990, 38, 1214. [11]
Prinzbach, H. et al., Angew. Chem. Int Ed. Engl. 1989, 28, 1253. [12] Uhlig, F. et al., Phosphorus, Sulfur & Silicon 1993, 81, 155; Uhlig, F. et al., Phosphorus, Sulfur & Silicon 1993,
84, 181. [13] Nájera, C. et al., J. Org. Chem. 2002, 67, 5216. [14] Solladié-Cavallo, A. et al., Synlett. 1997, 217. [15] Solladié-Cavallo, A. et al., Synlett. 2000, 327. [16] SolladiéCavallo, A. et al., Eur. J. Org. Chem. 2000, 1077; Solladié-Cavallo, A. et al., Tetrahedron Lett. 2000, 41, 7309. [17] Palomo, C. et al., Tetrahedron Lett. 2000, 41, 1283. [18]
Winterfeldt, E. et al., Eur. J. Org. Chem. 1998, 2811.
For questions about the pricing or to order: call your local Sigma-Aldrich Office
(see back cover) or visit our web site at www.sigma-aldrich.com/fluka
Tetrameric Phosphazene Bases (P4)
The two P4 phosphazen bases offered by Fluka differ slightly with respect to their steric hindrance and basicity (Table 5).
Table 5. Order of Basicity for P4 Bases
Order of steric hindrance:
P4-t-Oct
>>
P4-t-Bu
Fluka Product Number:
79422
79421
Basicity (MeCNpKBH+):
42.7
41.9
P4-t-Bu[1] 79421 and P4-t-Oct 79422, offered as 1 M solutions in hexane have several important features. They are highly
sterically hindered, extremely hygroscopic, highly stable towards hydrolysis, 18 orders of magnitude more basic than
DBU,[2] and already in the basicity range typical of organolithium bases. Both 79421 and 79422 are particularly suitable
for deprotonation (activation) of pronucleophiles, although also deprotonations for spectroscopic investigations,[3-7]
epimerisations,[8] double bond shifts,[9] β-eliminations,[9-12] and Li+ complexation (alkyl-lithium activation)[13,14] have been
reported. See Table 6 for a list of our P2 bases with their properties, package size etc.
79421
79422
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Tetrameric Phosphazene Bases (P4)
Table 6. Phospazene bases P4
79421 Phosphazene base P4-t-Bu solution
1-tert-Butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylidenamino]-2Λ5,4Λ5-catenadi(phosphazene)
purum, ~1.0 M in n-hexane C22H63N13P4 Mr 633.7 [111324-04-0] 1 ml, 5 ml, 25 ml
79422 Phosphazene base P4-t-Oct solution
1-tert-Octyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)
phosphoranylidenamino]-2Λ5,4Λ5-catenadi(phosphazene)
C26H71N13P4 Mr 689.8 [153136-05-1] 1 ml, 5 ml
purum, 1.00 M ± 0.02
M in n-hexane
Applications. These bases attract increasing interest in the field of anionic copolymerisation[13-18] and have also been
utilized for solid-phase synthesis[6] related to combinatorial chemistry.[19,20] They have been reported to support
alkylations,[1,21-31] Michael-additions,[15,32,33] aldol-reactions,[28,34-37], epoxide-opening,[17,19,38,39] acylations,[40] sulfonylations,[41]
anionic oxy-Cope rearrangements,[42] oxidation of carbanions[37], and transition metal-induced coupling reactions.[29,43]
Among the successfully converted low acidic substrates are alcohols[35,42], amides[39,41], peptides (N- and C-activation),[24]
porphyrines,[4] phosphines,[26] H-phosphonates,[31] esters,[5,25,27,35] β-alkoxyesters[21] and -lactones[23][21][8], and
β, γ, δ-lactones,[23,30] thioesters,[40] sulfones,[3,34] episulfones,[28] benzothiazole,[21] and benzyl aryl ethers.[36] β-Hydroxysulfones,[34] phosphonothioates,[31] enol triflates,[40] benzofuranes,[36] and subphthalocyanines[44] are thus efficiently synthesized.
References: [1] For properties, purification, handling, storage, and precautions see: L. A. Paquette, “Encyclopedia of Reagents for Organic Synthesis”, Wiley, 1995, Vol. 6,
p. 4110. [2] Schwesinger, R. et al., Liebigs Ann. 1996, 1055. [3] Gais, H.-J. et al., Angew. Chem. Int. Ed. Engl. 1988, 27, 1092). [4] Limbach, H.-H. et al., Angew. Chem. Int. Ed.
Engl. 1994, 33, 2215. [5] Melnyk, O. et al., Tetrahedron Lett. 2001, 42, 9153. [6] Melnyk, O. et al., J. Org. Chem. 2002, 67, 526. [7] Solladié-Cavallo, A. et al., Tetrahedron
Lett. 2002, 43, 415. [8] Kudis, S., Helmchen, G., Tetrahedron 1998, 54, 10449. [9] Maddaluno, J. et al., J. Org. Chem. 1998, 63, 5110. [10] Ley, S. V. et al., Tetrahedron: Asymm.
1994, 5, 2609. [11] Ley, S. V., Mio, S., Synlett. 1996, 789. [12] Grimme, W. et al., J. Chem. Soc. Perkin Trans. 2 1999, 1959. [13] Eßwein, B., Möller, M., Angew. Chem. Int. Ed.
Engl. 1996, 35, 623. [14] Möller, M. et al., Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) 1996, 37, 647; Förster, S., Krämer, S., Macromolecules 1999, 32, 2783. [15]
Pietzonka, T., Seebach, D., Angew. Chem. Int. Ed. Engl. 1993, 32, 716; Börner, H. G., Heitz, W., Macromol. Chem. Phys. 1998, 199, 1815. [16] Molenberg, A., Möller, M.,
Macromol. Rapid Commun. 1994, 16, 449; Van Dyke, M. E., Clarson, S. J., Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) 1996, 37, 668; Van Dyke, M. E., Clarson, S. J., J.
Inorg. Organomet. Polymers 1998, 8, 111; Hupfield, P. C., Taylor, R. G., J. Inorg. Organomet. Polymers 1999, 9, 17. [17] Möller, M. et al., Macromol. Rapid Commun. 1996, 17,
143; Möller, M. et al., Macromol. Symp. 1996 (Intern. Symposium on Ionic Polymerization 1995), 331; Schlaad, H. et al., Macromolecules 2001, 34, 4302. [18] Memeger Jr., W.
et al., Macromolecules 1996, 29, 6475, 8568. [19] Brill, W. K.-D. et al., Synlett. 1998, 1085. [20] Wendeborn, S. et al., Synlett. 1999, 1121. [21] Schwesinger, R., Schlemper,
H., Angew. Chem. Int. Ed. Engl. 1987, 26, 1167. [22] Schwesinger, R., Nachr. Chem. Tech. Lab. 1990, 38, 1214. [23] Pietzonka, T., Seebach, D., Chem. Ber. 1991, 124, 1837.
[24] Pietzonka, T., Seebach, D., Angew. Chem. 1992, 104, 1543; Seebach, D. et al., Helv. Chim. Acta 1996, 79, 588. [25] Prinzbach, H. et al., J. Am. Chem. Soc. 1993, 115,
7173. [26] Uhlig, F. et al., Phosphorus, Sulfur & Silicon 1993, 81, 155; Uhlig, F. et al., Phosphorus, Sulfur & Silicon 1993, 84, 181. [27] Solladié-Cavallo, A. et al., J. Org. Chem.
1994, 59, 5343. [28] Muccioli, A. B., Simpkins, N. S., J. Org. Chem. 1994, 59, 5141-5143; Simpkins, N. S. et al., J. Chem. Soc. Perkin Trans. 1 1997, 323. [29] Fuji, K. et al., J.
Chem. Soc. Chem. Commun. 1999, 2289. [30] Hultin, P. G. et al., Tetrahedron 1996, 52, 8685. [32] Mioskowski, C. et al., Chem. Eur. J. 2002, 8, 2910. [32] Bloch, R. et al.,
Tetrahedron: Asymm. 1997, 8, 3665. [33] Chang, C. K. et al., Tetrahedron Lett. 1995, 36, 6408. [34] Solladié-Cavallo, A. et al., J. Org. Chem. 1996, 61, 2690. [35] Prinzbach,
H. et al., J. Org. Chem. 2001, 66, 5744. [36] Verkade, J. G. et al., Org. Lett. 2000, 2, 2409 (Aldol mit Benzylanion). [37] Motorina, I. A., Grierson, D. S., Tetrahedron Lett. 1999,
40, 7211. [38] Brill, W. K.-D., Tirefort, D., Tetrahedron Lett. 1998, 38, 787. [39] Spaltenstein, A. et al., Bioorg. Med. Chem. Lett. 2000, 10, 1159. [40] O´Neil, I. A. et al., Synlett.
1995, 151. [41] Ellis, D., Tetrahedron Asymm. 2001, 12, 1589. [42] Mamdani, H. T., Hartley, R. C., Tetrahedron Lett. 2000, 41, 747. [43] Palomo, C. et al., J. Chem. Soc. Chem.
Commun. 1998, 2091. [44] Hanack, M. et al., Synthesis 1996, 1139.
For questions about the pricing or to order: call your local Sigma-Aldrich Office
(see back cover) or visit our web site at www.sigma-aldrich.com/fluka
Verkade’s Bases
Verkade`s bases, football-shaped proazaphosphatrane molecules of type 1, are very strong bases due to the extraordinary
stability of 2 when 1 reacts with a proton.
(2)
(1)
Due to the stability of the protonated form 2, Verkade`s bases are about 8
orders of magnitude stronger as a Lewis base than any amine known, including
the prominently used DBU, DBN and Proton Sponge 14795 (for details see
further).
Applications. Verkade`s bases have been successfully applied in a variety of organic reactions, such as alkylations,
dehydrohalogenations, acylations,[1] a variety of condensation and organometallic reactions for carbon-carbon bond
formation.[2] A second characteristic of the novel cage molecules of type 1 is their ability to act as a superior catalyst for a
continuously widening range of reactions[3-6] such as protecting alcohol groups with various silyl groups during multistep
syntheses,[4] trimerizing isocyanates to isocyanurates[5] and the synthesis of alpha, beta-unsaturated nitriles.[6]
Table 7. Verkade’s bases
55,695-5 2,8,9-Triisopropyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane
2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane,2,8,9-tris(1-methylethyl)]
C15H33N4P
Mr 304.3
[175845-21-3]
1 g, 5 g
56,588-1 2,8,9-Triisobutyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane
Mr 342.51
[331465-71-5]
Purity ~97%
C18H39N4P
1 g, 5 g
References: [1] S. Arumugam, D. McLeod, J. G. Verkade, J. Org. Chem., 1997, 62, 3677. [2] S. Arumugam, D. McLeod, J. G. Verkade, J. Org. Chem., 1997, 62, 4827. [2] B.
D’Sa, P. B. Kisanga, J. G. Verkade, J. Org. Chem., 1998, 63, 3691. [3] P. B. Kisanga, B. D’Sa, J. G. Verkade, J. Org. Chem., 1998, 63, 10057. [4] B. D’Sa, J. G. Verkade,
“P(MeNCH2CH2)3N: An Efficient Silylation Catalyst,” J. Am. Chem. Soc., 1996, 118, 12,832. [5] J.-S. Tang, J. G. Verkade, “P(MeNCH2CH2)3N as a Superior Catalyst in the
Conversion of Isocyanates to Isocyanurates,” Angew. Chem., Int. Ed. Engl., 1993, 32, 896. [6] P. B. Kisanga, J. G. Verkade, J. Org. Chem., 1999, 64, 4298.
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www.sigma-aldrich.com/glassware for a whole
overview, or send an eMail to our Aldrich Glass
Shop at [email protected] for a special design
For questions about the pricing or to order: call your local Sigma-Aldrich Office
(see back cover) or visit our web site at www.sigma-aldrich.com/fluka
Our Traditional Strong and Hindered Bases
We do not only offer you specialized bases, such as the phosphazene or Verkade’s bases, but we are also able to offer you
our traditional bases, such as DBU, DBN, n-BuLi etc (see for An alphabetic list Table 9, 10 and 11). These traditional
strong and/or hindered bases are well-known and frequently used tools in organic synthesis. It is interesting to take a look
at our strongly hindered base 14795. This compound is an extremely strong base for a tertiary amine. Protonation releases
the strain of the two amines, resulting in a so-called “Proton Sponge”. Take a look at Table 8 for the basicity strength for
some of our traditional bases!
Table 8. Basicity strength of some traditonal bases
Fluka Product Number
90605
69440
33481, 33482
33471
87844
22709
87900
76850
90780
90340
33480
27690
62760
Product Name
1,5,7-Triazabicyclo(4.4.0)dec-5-ene (TBD)
7-Methyl-1,5,7-triazabicyclo(4.4.0)dec-5-ene (MTBD)
1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)
1,5-Diazabicyclo[4.3.0]non-5-ene (DBN)
1,1,3,3-Tetramethylguanidine (TMG)
Quinuclidine
2,2,6,6-Tetramethylpiperidine (TMP)
Pempidine (PMP)
Tributlyamine
Triethylamine
1,4-Diazabicyclo[2.2.2]octan (TED)
Collidine
2,6-Lutidine (2,6-Dimethylpyridine)
pKBH+
25.98
25.44
24.33
23.89
23.3
19.51
18.64
18.62
18.09
18.46
18.29
14.77
13.92
MeCN
*Absolute values in acetonitrile. Data obtained from Prof. Dr. Schwesinger, University of Freiburg, Germany
The general strength of the traditional lithium bases follows the order:
LDA < MeLi < n-BuLi < sec-BuLi < tert-BuLi
Books:
Z33,820-6
Handbook of Reagents for Organic Synthesis:
Acidic and Basic Reagents
Hans J. Reich, John Wiley & Sons, Ltd, 1999, 508 pp.,
Hard cover, ISBN: 0471979252
Comments:
Consisting of four volumes, the Handbook of Reagents includes over 500 reagents selected
from the Encyclopedia of Reagents for Organic Synthesis. Each volume is self-contained and
focuses on a different class of reagents, chemical substances useful for producing a
chemical reaction. This current volume outlines acidic and basic reagents. Detailed
physical and chemical data are provided so the reader will understand the exact use for
a reagent and work with it properly. Adopting the basic format and size of the original
Encyclopedia, each volume contains an introduction, an
alphabetical arrangement of reagents as well as author and subject
indexes.
Visit sigma-aldrich.com/books, with over 1,700 books to help safe
you time in experimental development, troubleshooting and
training. Our eBookShelf is Your Center for Protocols and Technology!
For questions about the pricing or to order: call your local Sigma-Aldrich Office
(see back cover) or visit our web site at www.sigma-aldrich.com/fluka
Preservation of Moisture Sensitive Reagents
and molarity determinations
To help you preserve reagent quality, many Aldrich and Fluka air- and moisture-sensitive reagents
are packaged under nitrogen or argon in crown-cap bottles, with a 6mm diameter hole in the
crown-cap and a PTFE faced rubber liner under the crown-cap, for simple transfer of reagent
using syringe or cannula techniques. When the syringe needle or cannula is withdrawn, the PTFE
faced rubber liner reseals the bottle to prevent inflow of moist air which would react with the
reagent. Syringe techniques have the disadvantage that a partial vacuum is created in the bottle
by removal of reagent, this partial vacuum being sufficient to pull outside (moist) air through the
pierced crown-cap liner.To overcome this disadvantage, you can provide a blanket of dry nitrogen
or inert gas over the crown-cap, so that it is dry nitrogen or inert gas which replaces the reagent
in the bottle, and contact of bottle contents with moist air is avoided. The following products will enable you to provide
an effective blanket of dry nitrogen or inert gas over our crown-cap bottles.
Aldrich Sure/Seal septum inlet transfer adapter
This adapter screws over the crown cap, seating on a large o-ring that fits the bottle neck for an
air-tight seal. Dry nitrogen or inert gas may be introduced by the side arm, then the cap on the
vertical arm removed and replaced with either a fold-over rubber septum or the septum cap
provided. Syringe techniques may be used to remove the desired amount of reagent, with the
syringe needle passing vertically through the adapter and crown-cap. The reagent removed is
replaced by dry nitrogen or inert gas from within the adapter, protecting the contents of the
bottle from air or moisture.
Aldrich product number Z40,718-6
Oxford Sure/Seal storage valve cap
This valve cap works on a similar principle to the transfer adapter described above, with the
additional feature of a plunger cap that provides better protection for long term storage. This
valve cap screws over the crown cap, onto the bottle neck for an air-tight seal. Dry nitrogen or
inert gas may be introduced by the side arm and the plunger cap on the vertical arm removed
and replaced with a fold-over rubber septum.
Aldrich product number Z40,626-0
Syringe techniques may be used to remove the desired amount of reagent, with the syringe needle passing vertically
through the valve cap and crown-cap. The reagent removed is replaced by dry nitrogen or inert gas from within the valve
cap, protecting the contents of the bottle from air or moisture. After removing bottle contents, the plunger cap is replaced,
before the dry Nitrogen or inert gas supply is disconnected. The plunger part is long enough to pass by the side arm,
effectively sealing the bottle with dry nitrogen or inert gas over the crown-cap, providing an effective positive seal for long
term storage of the bottle.
Info on titration methods to determine the molarity:
As the concentrations of commercial solutions of e.g. n-BuLi or t-BuLi vary appreciably, and change during storage time,
it is always recommended to determine the exact molarity of the solution prior to use.[1] There can be found several
methods for this in literature:
The classical Gilman double titration method is described in detail by Wakefield.[2] A recommended method for routine
analysis involves titration of the reagent with s-butyl alcohol using 1,10-phenanthroline or 2,2`-biquinoline (35020) as
indicator.[3] A variety of other methods have been described as well.[4]
References: [1] Handbook of Reagents for Organic Synthesis: Acidic and Basic Reagents, H.J. Reich, John Wiley & Sons, Ltd, 1999, 508, Hard Cover, ISBN 0471979252
(Z33,820-6) [2] Wakefield, B. J., Organolithium Methods; Academic: San Diego, 1988. [3] Watson, S. C.; Eastman, J. F. Journal of Organometallic Chemistry 1967, 9, 165
[4] (a) Collins, P. F.; Kamienski, C. W.; Esmay, D. L.; Ellestad, R. B. Anal Chem. 1961, 33, 468. (b) Crompton, T. R. Chemical Analysis of Organometallic Compounds; Academic:
New York, 1973. (c) Kofron, W. G.; Baclawski, L. M. Journal of Organic Chemistry 1976, 41, 1879. (d) Lipton, M. F.; Sorensen, C. M.; Sadler, A. C.; Shapiro, R. H. Journal of
Organometallic Chemistry 1980, 186, 155. (e) Winkle, M. R.; Lansinger, J. M.; Ronald, R. C. CC 1980, 87. (f) Bergbreiter, D. E.; Pendergrass, E. Journal of Organic Chemistry
1981, 46, 219. (g) Juaristi, E.; Martinez-Richa, A.; Garcia-Rivera, A.; Cruz-Sanchez, J. S. Journal of Organic Chemistry 1983, 48, 2603.
Please take a look at www.sigma-aldrich.com under Aldrich; Technical bulletin AL-134,
for obtaining detailed information about Handling Air-Sensitive Reagents
Amine based traditional bases
Table 9.
27690 sym.-Collidine, 2,4,6-Trimethylpyridine, 2,4,6-Collidine
puriss. p.a., ≥99.0% (GC) C8H11N
Mr 121.8 108-75-8
100 ml, 500 ml
20615 2-tert-Butyl-1,1,3,3-tetramethyl-guanidine
purum, ≥97.0% (GC)
C9H21N3 Mr 171.3 29166-72-1
5 ml, 25 ml
33482 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)
2,3,4,6,7,8,9,10-Octahydropyrimidol[1,2-a]azepine
H. Oediger, et al., Synthesis 1972, 591; N. Ono et al., Bull. Chem. Soc. Jpn. 1978, 51, 2401;
C. G. Rao, Org. Prep. Proc. Intl. 1980, 12, 225; N. Ono et al., Bull. Chem. Soc. Jpn. 1979, 52, 1716.
puriss., ≥99.0% (GC)
C9H16N2
Mr 152.2 [6674-22-2]
50 ml, 250 ml, 1 l
33481 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)
2,3,4,6,7,8,9,10-Octahydropyrimidol[1,2-a]azepine
purum, ≥98.0% (GC)
C9H16N2 Mr 152.2 [6674-22-2]
50 ml, 250 ml, 1 l
33471 1,5-Diazabicyclo[4.3.0]non-5-ene (DBN)
Amidine base used for dehydrohalogenation reactions to olefins: H. Oediger, et al., Synthesis 1972, 591.
purum, ≥98.0% (GC)
C7H12N2
Mr 124.2 [3001-72-7]
25 ml, 100 ml, 500 ml
33480 1,4-Diazabicyclo(2.2.2)octane (TED), Dabco™ , Triethylenediamine
purum, ≥95% (NT)
C6H12N2 Mr 112.18 280-57-9
36672 N,N-Dicyclohexylmethylamine
purum, ≥97.0% (GC)
C13H25N
Mr 195.35 7560-83-0
31960 N,N-Diethylaniline, free of mono-compounds
puriss. p.a., ≥99.5% (GC) C10H15N Mr 149.24 91-66-7
38395 N,N-Diisopropyl-2-ethylbutylamine
purum, ≥98.0% (GC)
C12H27N Mr 185.35 200342-33-2
100 g, 500 g
250 ml, 1 l
100 ml, 500 ml
25 ml, 100 ml
38431 N,N-Diisopropylmethylamine
purum, ≥98.0% (GC)
C7H17N
Mr 115.22 10342-97-9
10 ml, 50 ml
38438 N,N-Diisopropyl-3-pentylamine
purum, ≥99.0% (GC)
C11H25N
Mr 171.33 68714-10-3
1 ml, 5 ml
39430 N,N-Dimethylaniline
puriss. p.a., ≥99.5% (GC), C8H11N
Mr 121.18 121-69-7
100 ml, 500 ml
34775 2,6-Di-tert-butyl-4-methylpyridine
A sterically hindered, non-nucleophilic base which distinguishes between Brönsted (protonic) and Lewis acids. Enables the direct high-yield
conversion of aldehydes and ketones to vinyl triflates. Synthesis 1980, 283; Org. Synth. 1990, 68, 138. Hindered base for the O-alkylation of
carbohydrates with alkyl triflates: J. Arnarp, et al., Acta Chem. Scand. Ser. B 32, 4, 1978; J. M. Berry, L. D. Hall, Carbohydr. Res. 1976, 47,
307; M. G. Ambrose, A. W. Binkley, J. Org. Chem. 1983, 48, 674; Base for the conversion of carbonyls in vinyl triflates with triflic
anhydrides; P. B. Stang, W. Treptow, Synthesis 1980, 283. M. E. Wright, S.R. Pulley, J. Org. Chem. 1989, 54, 2886; W. J. Scott, et al., Org.
Synth. 1990, 68, 116.
purum, ≥97.0% (GC)
C14H23N
Mr 205.3 [38222-83-2]
For questions about the pricing or to order: call your local Sigma-Aldrich Office
(see back cover) or visit our web site at www.sigma-aldrich.com/fluka
5 g, 25 g
Amine based traditional bases
03440 N-Ethyldiisopropylamine solution, Hünig's base, N,N-Diisopropylethylamine
Proton scavenger used in peptide coupling,1 enolboration,2 Pd(0)-catalyzed alkoxycarbonylation of allyl phosphates and acetates,3 and as a
catalyst in vinyl sulfone synthesis.4 (1) J. Org. Chem. 1994, 59, 695. (2) ibid. 1993, 58, 7162. (3) ibid. 1993, 58, 1538, Synth. Commun.
1993, 23, 3073. Ref 4.
purum, ≥98.0% (GC)
C8H19N
Mr 129.2
62760 2,6-Lutidine, 2,6-Dimethylpyridine
Mr 107.16
purum, ≥96% (GC)
C7H9N
[7087-68-5]
50 ml, 250 ml, 1 l
108-48-5
100 ml, 500 ml
69440 7-Methyl-1,5,7-triazabicyclo(4.4.0)dec-5-ene (MTBD)
1,3,4,6,7,8-Hexahydro-1-methyl-2H-pyrimido[1,2-a]pyrimidine
84030-20-6
purum, ≥98.0% (GC)
C8H15N3 Mr 153.23
5 ml, 25 ml
76830 3,3,6,9,9-Pentamethyl-2,10-diazabicyclo-(4.4.0)dec-1-ene (PMDBD)
1,2,3,4,4a,5,6,7-Octahydro-2,2,4a,7,7-pentamethylnaphthyridine
69340-58-5
purum, ≥% (GC)
C13H24N2 Mr 208.35
1g
76850 1,2,2,6,6-Pentamethylpiperidine (PMP), pempidine
One of the most strongly basic tertiary amines (sterically hindered and nonquaternizing): H. Z. Sommer et al., J. Org. Chem. 1971, 36, 824.
purum, ≥99.0% (GC)
C10H21N
90340 Triethylamine
puriss. p.a., ≥99.5% (GC) C6H15N
Mr 155.3
[79-55-0]
5 ml, 25 ml
Mr 101.19
121-44-8
250 ml, 1 l, 2.5 l
87844 1,1,3,3-Tetramethylguanidine (TMG)
puriss., ≥99.0% (GC)
C5H13N3 Mr 115.18
80-70-6
50 ml, 250 ml
14795 N,N,N',N'-Tetramethyl-1,8-naphthalenediamine (Proton Sponge®)
Very strong base with weak nucleophilic character due to steric effects. J. Chem. Soc., Perkin Trans. 2 1991, 857; R.W. Alder et al., Chem.
Commun. 1968, 723; R. L. Benoit et al., Can. J. Chem. 1987, 65, 996.
purum, ≥99.0% (NT)
C14H18N2 Mr 214.31
87900 2,2,6,6-Tetramethylpiperidine (TMP)
Mr 141.26
purum, ≥97.0% (GC)
C9H19N
20734-58-1
768-66-1
10 g, 50 g
10 ml, 50 ml
90603 1,5,7-Triazabicylco(4.4.0)dec-5-ene on polystyrene bound to polystyrene crosslinked with 2% DVB,
Polymer-supported, strong, hindered pentasubstituted guanidine base
c(base): ~2.6 mmol/g resin
5 g, 25 g
90605 1,5,7-Triazabicyclo(4.4.0)dec-5-ene, 1,3,4,6,7,8-Hexahydro-2H-pyrimido[1,2-a]pyrimidine (TBD)
5807-14-7
10 g, 50 g
purum, ≥98.0% (T)
C7H13N3 Mr 139.19
90780 Tributylamine
puriss. p.a., ≥99.0% (GC) C12H27N
Mr 185.36
102-82-9
90850 2,4,6-Tri-tert-butylpyridine
purum, ≥98.0% (CHN)
C17H29N
Mr 247.43
20336-15-6
1 g, 5 g
93438 Tris(trimethylsilyl)amine
purum, ≥97.0% (GC)
C9H27NSi3 Mr 233.58
1586-73-8
5 g, 25 g
22709 Quinuclidine
purum, ≥95% (NT)
100-76-5
5 g, 25 g
C7H13N
Mr 111.19
For questions about the pricing or to order: call your local Sigma-Aldrich Office
(see back cover) or visit our web site at www.sigma-aldrich.com/fluka
100 ml, 500 ml
Lithium based traditional bases
Table 10.
20160 Butyllithium solution, n-BuLi
techn., ~1.6 M in hexane
C4H9Li
Mr 64.06
[109-72-8]
100 ml, 500 ml
20164 Butyllithium solution, n-BuLi
techn., ~2.5 M in toluene
C4H9Li
Mr 64.06
[109-72-8]
100 ml, 500 ml
20159 Butyllithium solution, n-BuLi
purum, ~2.7 M in heptane
C4H9Li
Mr 64.06
[109-72-8]
100 ml, 500 ml
20161 Butyllithium solution, n-BuLi
purum, ~10 M in hexane
C4H9Li
Mr 64.06
[109-72-8]
100 ml
[598-30-1]
100 ml, 500 ml
94439 tert-Butyllithium solution, t-BuLi, lithium-2-methyl-2-propanide
purum, 1.6-3.2 M in heptane
C4H9Li
Mr 64.06
[594-19-4]
100 ml
20190 tert-Butyllithium solution, t-BuLi, Lithium-2-methyl-2-propanide
Mr 64.06
[594-19-4]
techn., ~1.5 M in pentane
C4H9Li
100 ml, 500 ml
53200 Hexyllithium solution
purum, ~2.5 M in hexane
100 ml, 500 ml
20185 sec-Butyllithium solution, sec-BuLi, Lithium-2-butanide
Mr 64.06
purum, ~1.3 M in cyclohexane
C4H9Li
[21369-64-2]
62491 Lithium diisopropylamide solution, LDA
~2 M in THF/heptane/ethylbenzene, liquid, brown
A non-pyrophoric LDA-THF complex. Strong, sterical hindered base used for the formation of carbaniones: Aldrichimica Acta,1984 17, 80.
Lithium diisopropylamide as a hydride donor: Majewski M.; Tetrahedron Lett. 1988 29, 4057-60. The ¢3 + 2‘ intramolecular cycloaddition
reaction of azomethine ylides generated from benzylic N-oxides: Roussi G., Heterocycles 1990, 31, 1445.
techn.
C6H14LiN
Mr 107.1
[4111-54-0]
100 ml, 500 ml
67740 Methyllithium solution, MeLi
purum, ~5% in
CH3Li
diethyl ether (~1.6 M)
Mr 21.98
[917-54-4]
25 ml, 100 ml
67737 Methyllithium solution, MeLi
purum, ~1 M in
CH3Li
cumene/THF (~1.6 M)
Mr 21.98
[917-54-4]
50 ml, 250 ml
67741 Methyllithium lithium bromide complex solution
Nucleophilic methylating agent used in the synthesis of other methyl organometallics and in the preparation of methyl lactones from
carboxylic acids. J. Am. Chem. Soc. 1979, 101, 1455. Handbook of Reagents for Organic Synthesis: Acidic and Basic Reagents; Reich, H. J., Rigby,
J. H., Eds.; John Wiley & Sons: New York, 1999 (Z33,820-6).
techn., ~1.5 M in diethyl ether
CH3Li•BrLi Mr 108.8
[917-54-4]
For questions about the pricing or to order: call your local Sigma-Aldrich Office
(see back cover) or visit our web site at www.sigma-aldrich.com/fluka
100 ml, 500 ml
Potassium traditional bases
Table 11.
60071 Potassium bis(trimethylsilyl)amide solution, Hexamethyldisilazane potassium solution
Sterically hindered base employed in selective cyclization: J. Org. Chem. 1993, 58, 6177, 6874. Also used in the preparation of lanthanide
complexes: Organometallics 1993, 12, 2618, ibid. 1992, 11, 2003.
~0.5 M in toluene
C8H18KNSi2 Mr 199.5
[40949-94-8]
100 ml, 500 ml
60066 Potassium bis(trimethylsilyl)amide, Hexamethyldisilazane potassium salt
[40949-94-8]
purum, ≥95.0% (T)
C8H18KNSi2 Mr 199.5
25 g, 100 g
60100 Potassium tert-butoxide
techn., ≥94% (T)
C4H9KO
Mr 112.2
[865-47-4]
10 g, 100 g, 500 g
60098 Potassium tert-butoxide
purum, ≥97.0% (T)
C4H9KO
Mr 112.2
[865-47-4]
100 g, 500 g
60103 Potassium tert-butoxide solution
purum, ~1 M in
C4H9KO
tetrahydrofuran
Mr 112.2
[865-47-4]
100 ml, 500 ml
60102 Potassium tert-butoxide solution
techn., ~1 M in tert-butanol C4H9KO
Mr 112.2
[865-47-4]
100 ml, 250 ml
71337 Sodium tert-butoxide
purum, ≥97.0% (T)
Mr 112.2
[865-48-5]
C4H9KO
10 g, 100 g, 500 g
ALDRICH SCHLENK-TYPE GLASSWARE
This system is specifically designed for additions, chemical reactions, distillations, drying/evaporation, extractions, filtrations, recrystallizations, washing,
degassing, and transfers of solids and liquids. For small-scale manipulation of air- and moisture-sensitive reagents. Aldrich Schlenk-type glassware is available
with greaseless threaded B14/20 ground-glass joints and is compatible with the Aldrich All-in-One Glassware Kit.
•
•
•
•
Greaseless threaded B joints require no clamps
Narrow openings minimize infusion of air during manipulations
Side-arm stopcocks for evacuation of air and purging with inert gas
May be used with ordinary glassware with B joints
Threaded joint consists of an externally threaded female B joint and a corresponding male B joint with a threaded plastic nut and O-ring that seals above
the ground-glass joint to make a vacuum-tight, greaseless seal. A simple twist of the nut loosens the joint for safe disassembly.
Typical Operations Using Aldrich Schlenk-Type Glassware
In the diagrams that follow, apparatus components have been lettered for ease of identification.
M
Addition of Liquids
C
For the addition of an air-free solvent, or liquid to a solid.
Set-up: Addition funnel, reaction flask or tube and hex head stopper.
Q
WA
Q
Chemical Reaction
After securing the reaction flask and initiating stirring, the apparatus is
slowly rotated about the joint between the two adapters, allowing the
reagent solution to flow into the reaction flask.
Set-up: Two reaction flasks and two bent adapters.
D
T
R
For questions about the pricing or to order: call your local Sigma-Aldrich Office
(see back cover) or visit our web site at www.sigma-aldrich.com/fluka
Aldrich Glassware
ALDRICH SCHLENK-TYPE GLASSWARE continued
M
G
D
C
E
Q
Q
F
P
C
P
HB
WB
N
B
O
XA
XA
Q
AB
XB
R
R
Q
R
2
1
3
4
S
Distillation
Drying/Evaporation
Extraction and Filtration
Distillation under inert
atmosphere and/or reduced
pressure is easily
accomplished using this
apparatus.
This apparatus is useful for
removing solvents from
temperature-sensitive materials,
especially over long periods of
time.
Set-ups for the extraction and filtration of solids are illustrated above.
Set-up: A storage flask
connected to a Vigreux distilling
column, 3-way connecting
adapter, thermometer adapter,
Liebig condenser, vacuum
distillation adapter, and a reaction
and storage flask.
Set-up: Storage and reaction
flask via a bent adapter is
connected to a cold-trap
equipped with a connecting
adapter (in-line with glass
stopcock).
Set-up: Examples 1, 2, and 3 are arrangements of flasks and a filter funnel. Setup 2 also uses two angled adapters and 3 uses a straight adapter. Set-up 4 has a
low-temperature filter funnel connected to a Liebig condenser, equipped with a
vacuum adapter, and a reaction and storage flask.
M
WA
M
KA
L
U
WA
Y
R
XA
HA
KB
V
AA
AA
WA
KA
AB
V
XC
KA
J
2
R
Z
R
Filtration/Recrystallization
The H-Schlenk tube permits lowtemperature filtration if a large cooling
bath is used.The illustration shows a setup for recrystallization. Starting material
is transferred from the reaction and
storage tube on the far left, to into the
H-Schlenk tube where it is dissolved
with solvent from the dropping funnel,
filtered into the right leg, and
recrystallized. Purified material is
transferred to the sealing tube on the
far right.
Set-up: Double-tube recrystallizer (HSchlenk tube), reaction and storage
tube, dropping funnel, hex head
stoppers, straight adapter, joint cap and a
sealing tube.
Filtration/Washing/
Degassing
An air-sensitive sample
dispersed in a wash solvent is
loaded via syringe at the top
inlet through a septum.
Vacuum and inert gas
pressure produces the
washing action.The stopcocks
on the side-arm then redirect
the inert gas for filtration.
Set-up: Filter/washer/
degasser unit with a rubber
septum at the top attached to
a reaction flask.
1
U
Filtration/ Washing
Transfer of Solids
A precipitate may be
collected and washed using
this apparatus.
Set-up: No. 1 has a solid
transfer vessel attached to a
filter funnel via a reducing
adapter, straight adapter an
joint caps.
Set-up: Reaction and
storage flask connected to a
double-ended filter, to a
straight adapter, followed by
a 3-way connecting adapter
connected to a reaction and
storage flask and to an
addition funnel with a hex
head stopper.
No. 2 shows a sealing tube
attached to the side-arm of
the solid transfer vessel.
For questions about the pricing or to order: call your local Sigma-Aldrich Office
(see back cover) or visit our web site at www.sigma-aldrich.com/fluka
Aldrich Glassware
ALDRICH SCHLENK-TYPE GLASSWARE continued
Adapters
Description
B Joint*
AA. Straight adapter
2-F
AB.
Straight adapter with drip-tip
2-F
B.
105°-Bent adapter with hose barb
1-M, 1-F
C.
90°-Bent adapter
1-M, 1-F
D.
75°-Bent adapter
2-F
E.
Vacuum adapter
1-M
F.
Thermometer adapter
1-M
G.
Adapter with glass stopcock
1-M, 1-F
HA. Three-way adapter
2-M, 1-F
HB.
Three-way adapter, 75° angle
2-M, 1-F
J.
Reducing adapter
45/40F to 14/20M
Cat. No.
Z17,321-5
Z22,044-2
Z16,744-4
Z22,012-4
Z17,304-5
Z16,753-3
Z16,756-8
Z22,024-8
Z17,332-0
Z16,745-2
Z22,036-1
Each
$21.40
32.30
38.70
35.30
27.90
21.00
32.40
78.80
61.50
49.20
38.60
Cat. No.
Z17,342-8
Z22,032-9
Z23,085-5
Z16,757-6
Each
$11.40
22.70
18.50
10.50/2
Cat. No.
Z22,041-8
Z16,751-7
Z16,752-5
Each
$70.70
51.20
57.60
Caps
Description
KA.
Female joint cap
KB.
Female joint cap
L.
Male joint cap
M.
Hex head stopper
B Joint*
F
45/40F
M
M
Additional
Schlenkware
1
2
3
4
Cold-traps, columns and condensers
Description
N.
Cold-trap for isothermic evaporation
O.
Vigreux distilling column, 150mm long
P.
Liebig condenser, 100mm long
B Joint*
2-F
1-M, 1-F
1-M, 1-F
Flasks and tubes
Description
Cap. (mL)
B Joint*
Cat. No.
Each
Q.
Reaction flask with glass stopcock on side-arm
25
M
Z22,026-4
$54.90
50
M
Z22,028-0
54.90
100
M
Z22,030-2
63.10
R.
Reaction and storage flask, Kjeldahl, with glass stopcock on side-arm
25
F
Z17,323-1
46.30
50
F
Z17,325-8
49.80
100
F
Z17,326-6
53.50
S.
Solvent storage flask with glass stopcock on side-arm
50
F
Z17,306-1
53.30
100
F
Z17,308-8
60.60
250
F
Z17,309-6
63.90
T.
Reaction and storage tube with glass stopcock on side-arm
25
F
Z17,312-6
42.40
50
F
Z17,322-3
42.30
U.
Solid-transfer vessel for transferring and packaging air-sensitive solid compounds under inert atmosphere,
has two side-arms with14/20M joints and a gas inlet with glass stopcock
75
3-M
Z22,059-0
106.70
V.
Sealing tube for use with solid-transfer vessel
15
F
Z22,043-4
32.30
WA. Addition funnel with Rotaflo® stopcock, and glass stopcock on side-arm
100
1-M, I-F
Z17,349-5
145.50
WB. Filter funnel with drip-tip and two glass stopcocks, one on side-arm, frit porosity 25-50µm
75
1-M, I-F
Z17,318-5
148.90
XA. Filter funnel with drip-tip and two side-arms each equipped with a glass stopcock, frit porosity 25-50µm
100
1-M, I-F
Z22,014-0
$155.50
XB.
Low temperature filter funnel, lower outlet is bent to allow for immersion of entire unit into a Dewar bath,
frit porosity 25-50µm
75
1-M, I-F
Z17,335-5
155.90
XC. Double-ended filter with a glass stopcock on each of the two side-arms, frit porosity 25-50µm
60
2-M
Z17,347-9
140.00
Y.
Filter/Washer/Degasser has septum-inlet, drip-tip, and PTFE stopcocks on side-arm, female top joint and
male bottom joint, frit porosity 25-50µm
100
1-M, I-F
Z23,228-9
414.70
Z.
Double-tube recrystallizers, frit porosity 25-50µm
4-M
Z17,336-3
124.70
*Unless specified, all joint sizes are B14/20.
6
5
7
Speciality Chemicals and Analytical Reagents
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