Water-saving Rice Production Technologies in Krishna Western Delta Command of Andhra Pradesh – An Economic Analysis

The economic analysis of water-saving rice production technologies, viz. system of rice intensification (SRI), semi-dry and rotational irrigation vis-à-vis farmers’ practice has been carried out based on the study executed in Modukuru pilot area of Guntur district of Andhra Pradesh. Among the three water-saving rice production technologies analyzed, the total cost of cultivation has been recorded highest in SRI (Rs 58645/ha), followed by rotational (Rs 47140/ha) and semi-dry (Rs 39321/ha). But, the per hectare yield has been found highest in SRI (6.85 t), followed by semi-dry (6.66 t) and rotational (6.2 t), inferring that all the three technologies have recorded higher yields over farmers’ practice of 5.5 t/ha. However, the net returns and B-C ratio are maximum in semi-dry (Rs 43,484/ha; 1.11), followed by rotational (Rs 30,085; 0.64) and SRI (Rs 26,466/ha; 0.45) methods. Similarly, the water-use efficiency has been found highest in SRI (8.53 kg/ ha-mm), followed by semi-dry (8.02 kg/ha-mm) and rotational (7.33 kg/ ha-mm) methods, while the water-use efficiency benefit (Rs/ha-mm) has been recorded maximum in semi-dry (52.39), followed by SRI (42.08) and rotational (35.56) methods. With the initiation of Andhra Pradesh Water Management Project, Bapatla, the area under semi-dry rice cultivation has been found increasing over a period of four years, from 0.6 ha in 2004-2005 to 22 ha in 2007 -2008.Agricultural and Food Policy,

It is “2-imino-4-thiazolidinones” and not thiohydantoins as the reaction product of 1,3-disubstituted thioureas and chloroacetylchloride

The products obtained by the reaction of 1,3-disubstituted thioureas with chloroacetylchloride are actually 2-imino-4-thiazolidinone derivatives and not thiohydantoins as previously reported (M. Kidwai, R. Venkataraman and B. Dave, Green. Chem., 2001, 3, 278). A highly efficient method for the preparation of 2-imino-4-thiazolidinones has been achieved from both symmetrical and unsymmetrical thioureasin the absence of base. The reaction gives a regioselective product for unsymmetrical thiourea which is dependent on the pKa's of the amines. For unsymmetrical thiourea, regioselective 2-imino-4-thiazolidinone formation takes place with the amine attached to the thiourea having lower pKa as part of the imino component and the amine having higher pKa contributes to the other heterocyclic nitrogen

Channeling the SmI₂ Reactions to the Radical Path: Radicals Resisting Reduction by SmI₂

Studies on the reaction of 4-(2,2-diphenylvinyl)­pyridine with SmI₂ revealed that the intermediate radical strongly resists further reduction to the corresponding anion. The resistance of the radical to accepting another electron is traced to its stabilization by the nitrogen lone pair. The literature suggests that oxygen may also play a role similar to that of nitrogen in directing the course of the reaction toward radical rather than to anionic chemistry

Bromineless bromine as an efficient desulfurizing agent for the preparation of cyanamides and 2-aminothiazoles from dithiocarbamate salts

n a one-pot procedure, bromineless brominating reagent 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) has been used as a desulfurizing agent in the preparation of organic cyanamides and substituted thiazoles starting from dithiocarbamic acid salts. In this approach, alkyl/aryl isothiocyantes were first obtained by the desulfurization of dithiocarbamic acid salts with EDPBT. The in situ–generated isothiocyanates reacts with an aqueous ammonia, forming alkyl or aryl thioureas, which on subsequent oxidative desulfurization with EDPBT led to the formation of corresponding cyanamides in good yields. Alternatively, an efficient one-pot synthesis of substituted thiazoles has been achieved by the condensation of the in situ–generated 1-aryl thioureas with the in situ–generated α-bromoketones from ketones, again using EDPBT. The reagent EDPBT can be easily prepared from the readily available reagents. Desulfurizing ability dominates over its brominating ability for substrates amenable to bromination

Reduction of 4‑Styrylpyridine by SmI₂: An Inner Sphere Electron Tranfer Case Where the Binding Site Differs from the Reaction Center

In the reduction of 4-styrylpyridine by SmI₂, the binding site for SmI₂ differs from the reaction center. MeOH and TFE exhibit an unprecedented behavior showing a sigmoidic effect on the reaction rate, which levels off around 0.5–1 M. The reactions display autocatalytic behavior and a U shape dependence of the reaction rate on the HMPA concentration. With high likelihood, the reactions involve a proton coupled electron transfer step

Copper(I)-catalyzed cascade synthesis of 2-substituted 1,3-benzothiazoles: direct access to benzothiazolones

An efficient cascade process for the preparation of 2‐substituted 1,3‐benzothiazoles directly from 2‐haloaryl isothiocyanates and O or S nucleophiles by a Cu‐catalyzed, intramolecular, C–S bond formation has been developed. This cascade method is viable for the efficient syntheses of both O‐ and S‐substituted 1,3‐benzothiazoles. Furthermore, 1,3‐benzothiazol‐2(3H)‐ones having an alkyl group allow easy access to 1,3‐benzothiazolones

Desulfurization mediated by hypervalent iodine(III): A novel strategy for the construction of heterocycles

The desulfurization ability of diacetoxyiodobenzene (DIB) has been explored in the preparation of isothiocyanates from the corresponding dithiocarbamate salts. The in situ generated isothiocyanates reacted with o‐phenylenediamine and o‐aminophenol to form monothioureas, which, on treatment with a further equivalent of DIB in one pot, gave benzimidazoles and aminobenzoxazoles, respectively. Aliphatic 1,2‐diamines on reaction with 2 equiv. of isothiocyanate followed by treatment with DIB gave imidazolidenecarbothioamides, whereas the treatment of aromatic 1,2‐diaminebis(thioureas) yielded benzimidazoles with the concurrent formation of isothiocyanate. The driving force for the formation of the latter is the aromatization of the product. The use of DIB makes these methods simpler and more efficient, giving high yields of the desired products in one pot

Molecular iodine mediated preparation of isothiocyanates from dithiocarbamic acid salts

We have developed a general economical and environmentally benign method for the preparation of isothiocyanates from the corresponding dithiocarbamic acid salts by using cheap and readily available reagent molecular iodine. This is perhaps the most efficient method reported so far for the synthesis of isothiocyanates. The reagent is easily available and nontoxic, and the precipitated sulfur can be removed easily; hence, this method is most suitable for large‐scale synthesis

Arylthioureas with bromine or its equivalents gives no ‘Hugerschoff’ reaction product

The in situ generated aryl–alkyl unsymmetrical thiourea obtained by the reaction of an aryl isothiocyanate with an aliphatic secondary amine on treatment with bromine or its equivalent gave exclusively a product having a thioamido guanidino moiety and not the expected Hugerschoff product 2-aminobenzothiazole. A plausible reaction mechanism has been proposed for this unprecedented transformation and the scope has been extended to various substrates