Photo above is at RJ College, Ghatkopar, Mumbai,India, chembond, jul 2012
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Jasmone is a natural organic compound extracted from the volatile portion of the oil fromjasmine flowers. It is a colorless to pale yellow liquid that has the odor of jasmine. Jasmone can exist in two isomeric forms with differing geometry around the pentenyl double bond, cis-jasmone and trans-jasmone. The natural extract contains only the cis form, while synthetic material is often a mixture containing both forms, with the cis form predominating. Both forms have similar odors and chemical properties.
Jasmone is produced within plants by the metabolism of jasmonate, from linolenic acid by the octadecanoid pathway. It can act as either an attractant or a repellent for various insects. Commercially jasmone is used primarily in perfumes and cosmetics.
An attempt to make Z jasmone – an important constituent of many perfumes
In fact one synthesis uses the following as carbon sources:
cis (Z) jasmone ,
cas no 488-10-8, 3-methyl-2-[(2Z)-pent-2-en-1-yl]cyclopent-2-en-1-one
ref-(Can. J. Chem. 1978, Vol 56, p2301)
1 W. Theilheimer. Synthetic Methods of Organic Chemistry. Volume 31, 1977, p. 352
2 Tetrahedron, 39 (24), p. 4127, 1983
Thomas Koch, Katja Bandemer, Wilhelm Boland (1997). "Biosynthesis of cis-Jasmone: a pathway for the inactivation and the disposal of the plant stress hormone jasmonic acid to the gas phase?". Helvetica Chimica Acta 80 (3): 838–850.doi:10.1002/hlca.19970800318.
- L. Ruzicka, M. Pfeiffer (1933). "Über Jasminriechstoffe I. Die Konstitution des Jasmons". Helvetica Chimica Acta 16: 1208–1214. doi:10.1002/hlca.193301601153.
Coloured mechanisms in Organic Chemistry
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Nature chemistry, v3, pg140-145, 2011
The development of new means of activating molecules and bonds for chemical reactions is a fundamental objective for chemists. In this regard, visible-light photoredox catalysis has emerged as a powerful technique for chemoselective activation of chemical bonds under mild reaction conditions. Here, we report a visible-light-mediated photocatalytic alcohol activation, which we use to convert alcohols to the corresponding bromides and iodides in good yields, with exceptional functional group tolerance. In this fundamentally useful reaction, the design and operation of the process is simple, the reaction is highly efficient, and the formation of stoichiometric waste products is minimized.
A greener way to convert alcohols to their corresponding bromides and iodides using visible light and without generating wasteful by-products has been developed by US researchers. The new method could provide an industrially viable alternative to existing routes.
The transformation of alcohols to their corresponding halides is one of the most widely used reactions in organic synthesis, but traditional methods often require harsh conditions and can generate high levels of undesired stoichiometric waste by-products that are difficult to remove from the reaction mixture.
Corey Stephenson and colleagues at Boston University have converted alcohols to halides using a photocatalyst that absorbs blue light from a light-emitting diode (LED) and polyhalomethanes such as carbon tetrabromide (CBr4) and triiodomethane (CHI3) as the halide source.
The team employed a ruthenium (II) complex to absorb visible light to form an excited ruthenium (II) complex. This ‘excited state’ catalyst acts as a reducing agent by giving up an electron to CBr4 to form a ruthenium (III) complex which the team observed by fluorescence quenching experiments.
The CBr4 then dissociates to form a CBr3 radical and Br-. The CBr3 radical then combines with a dimethylformamide (DMF) solvent to produce a solvent active species that goes on to react with the alcohol to form the resulting halide at yields of up to 98 per cent.
DIELS ALDER RXN
We noted earlier that addition reactions of alkenes often exhibited STEREOSPEFICITY, in that the reagent elements in some cases added syn and in other cases anti to the the plane of the double bond. Both reactants in the Diels-Alder reaction may demonstrate stereoisomerism, and when they do it is found that the relative configurations of the reactants are preserved in the product (the adduct). The following drawing illustrates this fact for the reaction of 1,3-butadiene with (E)-dicyanoethene. The trans relationship of the cyano groups in the dienophile is preserved in the six-membered ring of the adduct. Likewise, if the terminal carbons of the diene bear substituents, their relative configuration will be retained in the adduct. Using the earlier terminology, we could say that bonding to both the diene and the dienophile is syn. An alternative description, however, refers to the planar nature of both reactants and terms the bonding in each case to be suprafacial (i.e. to or from the same face of each plane). This STEREOSPECITY also confirms the synchronous nature of the 1,4-bonding that takes place
NITRILE HYDROLYSIS UNDER ACIDIC CONDITIONS
NITRILE HYDOLYSIS, BASIC CONDITIONS
2D-NMR (HMQC, HMBC, 1H-1H COSY and NOESY), for rel- (1R,2S,3R,4R) p-menthane-1,2,3-triol 3-O-β-D-glucopyranoside (1)
New monocyclic monoterpenoid glycoside from Mentha haplocalyx Briq.
Gai-Mei Sheet al
Chemistry Central Journal 2012, 6:37
new monocyclic monoterpenoid glycosides, rel-(1R,2S,3R,4R) p-menthane-1,2,3-triol 3-O-β-D-glucopyranoside (1) were isolated from aqueous acetone extract of the aerial parts of Mentha haplocalyx Briq..
On the basis of spectroscopic methods, including 2D-NMR (HMQC, HMBC, 1H-1H COSY and NOESY), the structures of new were determined as rel- (1R,2S,3R,4R) p-menthane-1,2,3-triol 3-O-β-D-glucopyranoside (1)
Compound 1 was obtained as a pale amorphous powder. Its HR-ESI-MS displayed quasi-molecular-ion peak [M + Na]+ at m/z 373.1521 ([C16H30O8Na]+), and the EI-MS gave fragment-ion peaks at m/z 171 [M + 1–162(glucosyl)-H2O]+ and 153 [M + 1–162(glucosyl)-2H2O]+ corresponding to a molecular formula C16H30O8, with the presence of 16 carbon signals in the 13C-NMR spectrum.
The 1H- and 13C-NMR spectral data displayed the presence of two secondary methyl δ 0.81 (3H, dJ = 7.0 Hz, H-10), 0.92 (3H, dJ = 7.0 Hz, H-9)], a tertiary methyl δ 1.21 (3H, s, H-7)], two methylenes δ 1.37 (2H, dtJ = 11.7, 8.3 Hz, H-5), 1.40 (1H, m, H-6α) and 1.57 (1H, m, H-6β)], four methines (two of them was oxygenated) δ 3.82 (1H, dJ = 10.8, 9.2 Hz, H-3), 3.33 (1H, dJ = 10.8 Hz, H-2), 2.31 (1H, m, H-8), and 1.69 (1H, m, H-4)], and an oxygentated quaternary carbon, suggesting that compound 1 was a menthane-type monoterpene with three OH-groups
Moreover, 1H-1H COSY correlations were observed between H-C(9)/H-C(8)/H-C(10), H-C(8)/H-C(4), and H-C(6)/H-C(5)/H-C(4)/H-C(3)/H-C(2), that the deduced spin system implied that the three OH-groups were located at C(1), C(2) and C(3) in 1, respectively. In addition, one glucopyranosyl unit δ (H) 4.33 (1H, dJ = 8.2 Hz, H-(1′)), δ(C) 105.9 (C-1′)] was evident from 1H- and 13C-NMR of 1. The J value (8.2 Hz) of the anomeric proton concluded the β-configuration of the glucose moiety, suggesting that 1 was a p-menthane-1,2,3-triol glycoside.
This was further confirmed by the HMBC experiment, in which correlations of the glucosyl H-1′ (δ 4.33) with the C(3) (δ 81.9) were observed. Furthermore, other HMBC correlations confirmed the structure of compound 1. Thus, these 2D-NMR methods deduced compound 1 as p-menthane-1,2,3-triol 2-Oβ-D- glucopyranoside. The coupling constants of 10.8 Hz for H-C(3)/H-C(2), 9.2 Hz for H-C(3)/H-C(4) for 1 showed that H-C(2), H-C(3) and H-C(4) were axial protons.
The relative configuration at C(1) was determined from ROESY correlation of δ 1.21 (Me(7)) with H-2 (δ 3.33). It was in good agreement with those of rel-(1R,2S,3R,4R,6S) p-menthane-1,2,3,6-tetrol . Therefore 1 should possess rel-(1R,2S,3R,4R)-configuration.
Isatin, an extract from Strobilanthes cusia (Nees) Kuntze, was the base for synthesizing derivatives that were screened for antibacterial activity against oilfield water-borne bacteria. The bacterial groups are sulfate reducing, iron and total. The derivatives were characterized by spectrums and they showed good to moderate activity against sulfate reducing bacteria.
New bactericide derived from Isatin for treating oilfield reinjection water
Gang Chen, et al
Chemistry Central Journal 2012, 6:90 (28 August 2012)
Mesoporous AlPO4: A Highly Efficient Heterogeneous Catalyst for Synthesis of 5-Substituted 1H-Tetrazoles from Nitriles and Sodium Azide
Mesoporous AlPO4: A Highly Efficient Heterogeneous Catalyst for Synthesis of 5-Substituted 1H-Tetrazoles from Nitriles and Sodium Azide via [3 + 2] Cycloaddition
Vol. 41, No. 8 (August, 2012)
|Design Concept for High-LUMO-level Fullerene Electron-acceptors for Organic Solar Cells by Yutaka Matsuo on pg 754
Department of Chemistry, School of Science, The University of Tokyo
| This review article describes design concept,
synthesis, and features of fullerene derivatives having high lowest
unoccupied molecular orbital (LUMO) levels to achieve high open-circuit
voltage in organic thin-film photovoltaic devices. Installation of
organic electron-donating groups onto fullerene and decrease of the size
of the fullerene π-electron-conjugated system raise the LUMO levels,
affording high-performance organic solar cells. Addition of the methano
group as the smallest carbon addend to fullerene to obtain 56π-electron
fullerene derivatives is likely a promising strategy for this purpose.
IBX acid or 2-iodoxybenzoic acid is an organic compound used in organic synthesis as an oxidizing agent. This periodinane is especially suited to oxidize alcohols to aldehydes. The IBX acid is prepared from 2-iodobenzoic acid, potassium bromate and sulfuric acid.
The reaction mechanism for an oxidation of an alcohol to an aldehyde according the so-called hypervalent twisting mechanism involves a ligand exchange reaction replacing the hydroxyl group by the alcohol followed by a twist and a elimination reaction.
The hypervalent twisting mechanism during conversion of methanol to formaldehyde: a) ligand exchange reaction (activation energy 9.1 kcal/mol (38 kJ/mol), b) hypervalent twist 12.1 kcal/mol (51 kJ/mol), c) elimination 4.7 kcal/mol (20 kJ/mol)). There is steric repulsion between protons in red.
In certain non-catalytic reactions that diastereomer will predominate, which could be formed by the approach of the entering group from the least hindered side when the rotational conformation of the C-C bond is such that the double bond is flanked by the two least bulky groups attached to the adjacent asymmetric center.
The rule indicates that the presence of an asymmetric center in a molecule induces the formation of an asymmetric center adjacent to it based on steric hindrance.
In his 1952 publication Cram presented a large number of reactions described in the literature for which the conformation of the reaction products could be explained based on this rule and he also described an elaborate experiment (scheme 1) making his case.
The experiments involved two reactions. In experiment one 2-phenylpropionaldehyde (1, racemic but (R)-enantiomer shown) was reacted with the Grignard reagent of bromobenzene to 1,2-diphenyl-1-propanol (2) as a mixture of diastereomers, predominantly the threo isomer (see for explanation the Fischer projection).
The preference for the formation of the threo isomer can be explained by the rule stated above by having the active nucleophile in this reaction attacking the carbonyl group from the least hindered side (see Newman projection A) when the carbonyl is positioned in a staggered formation with the methyl group and the hydrogen atom, which are the two smallest substituents creating a minimum of steric hindrance, in a gauche orientation and phenyl as the most bulky group in the anti conformation.
The second reaction is the organic reduction of 1,2-diphenyl-1-propanone 2 with lithium aluminium hydride, which results in the same reaction product as above but now with preference for the erythro isomer (2a). Now a hydride anion (H-) is the nucleophile attacking from the least hindered side (imagine hydrogen entering from the paper plane).
^ Studies in Stereochemistry. X. The Rule of "Steric Control of Asymmetric Induction" in the Syntheses of Acyclic Systems Donald J. Cram, Fathy Ahmed Abd Elhafez J. Am. Chem. Soc.; 1952; 74(23); 5828–5835. Abstract
Aldol condensation: A simple teaching model for organic laboratory
To synthesize trans-dibenzalacetone from acetone and benzaldehyde using NaOH as the catalytic base in a 1:1 water/ethanol solvent
Prepare a 0.5M NaOH (20 mmol) solution in 40 mL of distilled water and prepare a 1M solution of benzaldehyde (40 mmol) in 40 mL of ethanol. Mix the two solutions throughly. Add 0.8 g (1.1 mL, 15 mmol) of acetone to the reaction mixture and stir for 30 minutes. Recover the product by suction filtration using a Buchner funnel.
Amount: 3.044 g
Appearance: Bright yellow crystals
Melting Point: 103-104°C (lit mp 113°C)
Purity: Very pure sample of trans-dibenzalacetone
This procedure produced pure trans-dibenzalacetone without having to recrystallize. The two characteristic doublets of trans-dibenzalacetone had coupling constants of 16.25Hz (located at 7.7ppm) and 15.5Hz (located at 7.1ppm). These coupling constants of near 15Hz indicates that the trans product was recovered.
The limiting reagent was the acetone (0.8 g, 15 mmol) and the precent yield of this reaction was 87%. An excess of benzaldehyde (1.33 equivalent) was used and the benzaldehyde was dissolved into the ethanol prior to being introduced into the reaction mixture.
3.044 g of pure trans-dibenzalacetone was produced in a yield of 87%
Mech-Dibenzalacetone is readily prepared by the crossed Aldol condensation between benzaldehyde and acetone under alkaline conditions. Acetone is a carbonyl compound that contains alpha hydrogens. Therefore, it can participate in the various condensation reactions that involve removal of an alpha hydrogen. Benzaldehyde, on the other hand, does NOT contain any alpha hydrogens. The following sequence of reactions indicates the pathway for the formation of dibenzalacetone.
The carbanion produced by this step reacts with the more active benzaldehyde rather than with a second molecule of acetone. Thus, the next step becomes:
Because a 2:1 molar ratio of benzaldehyde is used, the reaction continues.
The overall balanced equation is:
SYN OF UGI ADDUCT
To synthesize a Ugi aduct from Benzaldehyde, Furfuryl amine, Benzylisocyanide and BOC-GLY-OH in methanol using Ugi 4Component Reaction.
BOC-GLY-OH, STR IS
A solution of Benzaldehyde (212 uL, 2.09 mmol) and Furfuryl amine (FFA) (235uL, 2.66 mmol )was prepared in methanol-d4 in a 4mL volumetric flask to form an imine overnight. The next day a solution of BOC-GLY-OH(350 mg, 1.99 mmol), andBenzylisocyanide (240uL, 1.97 mmol) made up in a 4ml volumetric flask in methanol was added to the preformed imine. The product was filtered and washed with ice cold methanol (5mL).
Colorless Crystals; M.pt 146-148C;
1HNMR ( ppm, CDCl3) 1.43 (s, 9H), 4.18 (m, 2H), 4.43 (m, 2H), 4.48 (s, 2H), 5.46 (s, 1H), 5.68 (s, 1H), 5.94 (s, 1H), 6.09 (m, 1H), 6.30 (s, 1H), 7.10-7.50 (m 11H)
13C NMR ( ppm, CDCl3) 28.3, 42.5, 42.8, 43.6, 63.0, 79.5, 107.9, 110.3, 110.8, 127.4, 127.6, 128.6, 128.7, 129.6, 134.2, 137.7, 142.0, 149.5, 155.7, 169.0, 170.3;
FAB HRMS: m/z 478.2366; calcd for C27H31N3O5 (M+H).
|CubaneCubane (C8H8) is a synthetic hydrocarbon molecule that consists of eight carbon atoms arranged at the corners of a cube, with one hydrogen atom attached to each carbon atom. A solid crystalline substance, cubane is one of the Platonic hydrocarbons. It was first synthesized in 1964 by Philip Eaton, a professor of chemistry at the University of Chicago. Before Eaton and Cole's work, researchers believed that cubic carbon-based molecules could not exist, because the unusually sharp 90-degree bonding angle of the carbon atoms were expected to be too highly strained, and hence unstable. Once formed, cubane is quite kinetically stable, due to a lack of readily available decomposition paths|
|J. Am. Chem. Soc. 1964, 86, 962. (10.1021/ja01059a072)|
|J. Am. Chem. Soc. 1964, 86, 3157. (10.1021/ja01069a041)|
wohl ziegler rxn