Reactions of carbon dioxide with metal carbonyl anions

The reactivity of a series of metal carbonyl anions with CO₂ has been found to parallel their relative nucleophilicities. The highly nucleophilic species, C₅H₅Fe(CO)^?₂, reacts readily to give the dimer, (C₅H₅Fe(CO)₂)₂, and carbonate while Co(CO)^?₄ is unreactive. The reaction of ¹³CO₂ with C₅H₅Fe(CO)^?₂ results in the formation of the ¹³CO enriched dimer.     

Separation of oligogalacturonic acids by high-performance gel filtration chromatography on silica gel with diol radical.

Oligogalacturonic acids (OLGAs) ranging from two to nineteen residues in length were separated using high-performance gel filtration chromatography on a silica gel with diol radical. The optimum conditions (eluent, column temperature) for separation of OLGAs by high-performance gel filtration chromatography were investigated. The column used in this experiment allowed a high pressure of 4900 p.s.i. and a flow-rate of 2 ml/min. The stationary phase of silica gel stabilized the separation of OLGAs. The peaks of OLGAs separated using this column were assigned by comparing retention times with standards, and the molecular weights of the corresponding OLGAs were determined by fast atom bombardment mass spectrometry.     

Separation of acidic and neutral lipids by aminopropyl-bonded silica gel column chromatography.

The separation of acidic and neutral lipids by aminopropyl-bonded silica gel column chromatography is presented. Total lipid extracts from Escherichia coli and human spermatozoa were loaded onto pre-packed aminopropyl-bonded silica gel columns and the lipids separated into four fractions. Non-polar lipids including cholesterol esters, triglycerides, diglycerides, monoglycerides and cholesterol, were eluted with 4 ml of isopropanol-chloroform (1:2, v/v) (fraction 1); free fatty acids were eluted with 4 ml of 2% acetic acid in diethyl ether (fraction 2); neutral polar lipids, including phosphophatidylethanolamine, phosphatidylcholine, sphingomyelin and neutral glycolipids, were eluted with 4 ml of methanol (fraction 3); and, finally, polar acidic lipids, including phosphatidylglycerol, cardiolipin, phosphatidylinositol, phosphatidylserine, seminolipid lipid A and acidic glycosphingolipids, were eluted with 4 ml of chloroform-methanol-0.8 M sodium acetate (60:30:4.5, v/V/V) (fraction 4). The recoveries for the different lipids ranged between 89 and 98% and the intra-assay variation, expressed as the standard deviation, was less than 5%.     

Identification of alkylpyrocatechols by thin-layer chromatography on silica gel

Conclusions A method was developed for the chromatographic separation of the alkyl derivatives of pyrocatechol employing thin-layer chromatography on plates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2816–2817, December, 1971.     

硅胶柱色谱结合高速逆流色谱法分离纯化荷花中黄酮类化合物

采用硅胶柱色谱结合高速逆流色谱法分离纯化了荷花中3种黄酮类化合物。荷花粗提物先经过硅胶柱色谱初步分离,得到黄酮含量高的组分,再经过高速逆流色谱分离,以乙酸乙酯-乙醇-水-乙酸(4:1:5:0.025, v/v/v/v)为两相溶剂系统,上相为固定相,下相为流动相,在主机转速800 r/min、流速2.0 mL/min、检测波长254 nm条件下,从150 mg样品中一次性分离制备得到6.1 mg槲皮素-3-O-β-D-葡萄糖醛酸苷(I), 14.8 mg杨梅素-3-O-β-D-葡萄糖苷(II)和20.2 mg紫云英苷(III),经高效液相色谱检测其纯度分别为97.0%、95.4%、96.3%,并通过质谱和核磁共振氢谱、碳谱鉴定各化合物的结构。该方法简便、快速、节省溶剂,可以对荷花中的黄酮类化合物进行快速有效的分离纯化,具有较好的实用价值,为荷花资源的进一步开发应用提供了参考依据。     

Separation of geometrical isomers of sesquiterpene and diterpene alcohols on bare silica by carbon dioxide supercritical fluid chromatography

Summary The application of supercritical fluid chromatography (SFC) with modified carbon dioxide to the separation of geometrical isomers of several sesquiterpene or diterpene alcohols is reported. The chromatographic system consists of bare silica (250×4.6 mm i. d.) with carbon dioxide-methanol mobile phase and UV detection. A mixture of sesquiterpene alcohols, (2E-6E)-farnesol, -bisabolol, (E)-nerolidol and (Z)-nerolidol, and also of two diterpene alcohols, (R)- and (S)-geranyllinalol, was separated by SFC using a mixture of carbon dioxide modified with 0.5–1.0% methanol as mobile phase.     

Rapid separation of inorganic anions by capillary ion chromatography using monolithic silica columns modified with dilauryldimethylammonium ion.

The rapid separation of inorganic anions was determined by capillary ion chromatography using monolithic silica capillary columns modified with dilauryldimethylammonium bromide. The stability of the modified stationary phase was satisfactory owing to a strong hydrophobic interaction between the lauryl groups of the reagent, even if the eluent did not contain dilauryldimethylammonium ion. Bromide in seawater samples could be determined by the present system. The repeatability of a retention time of bromide for six successive measurements was around 1.8% when a 500 mM sodium chloride aqueous solution was used as the eluent. Seawater samples were directly injected onto the prepared column without any interference of matrix ions, because an aqueous solution of high-concentration sodium chloride could be used as the eluent. Bromide in seawater samples could be determined within 2 min.     

负载型氨基酸离子液体的制备及其对二氧化碳的吸附性能

采用浸渍蒸发法将四甲基铵甘氨酸([N1111][Gly])和四甲基铵赖氨酸([N1111][Lys])两种离子液体分别负载到硅胶(SG)表面,利用EA、TGA、BET和FT-IR等技术对所得到的吸附剂进行表征,考察了离子液体种类、离子液体负载量和温度等条件对其CO_2吸附性能的影响。结果表明,离子液体成功负载到硅胶表面,所制得的负载型氨基酸离子液体对二氧化碳具有良好的吸附性能。在所考察的温度范围(303.15-323.15 K)内,温度越高,平衡吸附量越小;在负载量为10%-60%,随着负载量的增加,平衡吸附量先增加后减小。对于[N1111][Gly]/SG,当负载量为22.4%(质量分数)、吸附温度为30℃、压力为0.1 M Pa时,二氧化碳的平衡吸附量可达到41 mg/g(相对于1 mol AAILs吸附0.62 mol CO_2),而且,吸附20 min即可达到平衡吸附量的90%。吸附剂在循环使用六次之后,其结构与性能均保持良好。     

Thin-layer chromatography of steroids on microplates with fixed silica gel

Summary 1. A method for chromatographing steroids on microplates with silica gel of types KSK and KSM has been developed.2. The possibility of using a solution of iodine in potassium iodide to detect steroid compounds has been demonstrated and the sensitivity of this reaction has been determined.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 5, pp. 321–325, 1966     

Photoelectron imaging of hydrated carbon dioxide cluster anions

The effects of homogeneous and heterogeneous solvation on the electronic structure and photodetachment dynamics of hydrated carbon dioxide cluster anions are investigated using negative-ion photoelectron imaging spectroscopy. The experiments are conducted on mass-selected [(CO(2))(n)()(H(2)O)(m)()](-) cluster anions with n and m ranging up to 12 and 6, respectively, for selected clusters. Homogeneous solvation in (CO(2))(n)()(-) has minimal effect on the photoelectron angular distributions, despite dimer-to-monomer anion core switching. Heterogeneous hydration, on the other hand, is found to have the marked effect of decreasing the photodetachment anisotropy. For example, in the [CO(2)(H(2)O)(m)()](-) cluster anion series, the photoelectron anisotropy parameter falls to essentially zero with as few as 5-6 water molecules. The analysis of the data, supported by theoretical modeling, reveals that in the ground electronic state of the hydrated clusters the excess electron is localized on CO(2), corresponding to a (CO(2))(n)()(-).(H(2)O)(m)() configuration for all cluster anions studied. The diminishing anisotropy in the photoelectron images of hydrated cluster anions is proposed to be attributable to photoinduced charge transfer to solvent, creating transient (CO(2))(n)().(H(2)O)(m)()(-) states that subsequently decay via autodetachment.     

Theoretical analysis of pyrrole anions addition to carbon disulfide and carbon dioxide

Quantum chemical analysis (MP2/6‐31+G*) of the pyrrole anions addition to carbon disulfide and the substitution effects therein shows that pyrrole‐2 (5)‐carbodithioates are thermodynamically the most stable compounds, while 1‐isomer obtained from the unsubstituted pyrrole is likely a kinetic product. Steric hindrances destabilize N‐adducts when a methyl substituent appears in a 2(5) position and the 2,5‐dimethyl‐1‐pyrrolecarbodithioate anion turns out to be even less stable than the 2,5‐dimethyl‐3‐pyrrolecarbodithioate anion. By contrast, pyrrole‐1‐carboxylates are calculated to be the most stable adducts of CO₂ with pyrrole anions. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Reactions of benzyldiphenylphosphine with Pd(II) sources on silica gel

Depending on the conditions used, reactions of benzyldiphenylphosphine (HL¹) with Na₂PdCl₄ on silica gel or with Pd(OAc)₂ on the same absorbent followed by treatment with LiCl provide one or more of the four compounds: the cyclopalladated binuclear complex [(μ-Cl)PdL¹]₂ (1), cis and trans isomers of the coordination complex PdCl₂(HL¹)₂ (3), the binuclear coordination complex [(μ-Cl)PdCl(HL¹)]₂ (4), and compound PdCl₂(HL¹)₃ (5). The 56% yield of complex 1 achieved using the reaction with Na₂PdCl₄ and NaOAc on SiO₂ is higher than that reported for the direct cyclopalladation of PBnPh₂ with Pd(OAc)₂ in AcOH. X-ray diffraction studies of the cyclopalladated dimer 1 and the coordination complex cis-3 are reported.