1,720,965 research outputs found
Formation of Substituted Benzo[a]heptalenes via Bergman Cyclization of Vicinal Di(ethynyl)-heptalenes
Full text linkBy Hafner\u27s synthesis, dimethyl heptalene-4,5-dicarboxylates are easily available from azulenes and dimethyl acetylene-dicarboxylate. Treatment with Takai reagent leads to 4-acetylheptalene-5-carboxylates, which by the procedure of Negishi et al. are further transformed into 4-ethynyl-heptalene-5-carboxylates. Reduction to heptalene-5-methanols, followed by Swern oxidation yields the corresponding heptalene-5-carbaldehydes. Treatment with trimethylsilyldiazomethane in the presence of butyllithium gives 4,5-di(ethynyl)-heptalenes, which on heating in chlorobenzene in the presence of cyclohexa-1,4-diene are transformed into benzo[a]heptalenes
From Maleic Anhydrides to Substituted Resorcinols
Full text linkSymmetrically substituted maleic anhydrides react at -78 °C with lithiomethyl phenyl sulfone to give the corresponding 4-hydroxy-4-(phenylsulfonylmethyl)-buteno-4-lactones, which, on treatment with Mel/K2CO3 in acetone, are transformed into 5-methyl-5-phenylsulfonylcyclopent-2-ene-1,4-diones. These compounds rearrange in the presence of an excess of lithiomethyl phenyl sulfone at -78 °C and then butyllithium at -5 °C to ambient temperature into 4,5-disubstituted 6-methyl-2-phenylsulfonyl-resorcinols
Pteridines CVIII Reactions of 6, 7-Dichloro-I, 3-dimethyllumazine with Sulfur-Nucleophiles
No full text6,7-Dichloro-1,3-dimethyllumazine (1) and various 6-chloro-7-O-, S- and N-subst.-1,3-dimethyllumazines (2-7) react under relatively mild reaction condiditions with S-nucleophiles to the corresponding 6-mercapto derivatives 8-16. Treatment of 1 with sodium benzylmercaptide at room temperature led to di-( 6- chloro-1,3-dimethyllumazine-7-yl)sulfide (17) whereas thiourea caused transformation to the corresponding 7,7-disulfide 18. 7-Mercapto-1,3-dimethyl-6(5H)lumazinethione (12) can be modified widely by alkylations to open-chain (21-23, 27-29) or cyclic 6,7-bis-alkylthio derivatives (24-26) and acylations with phosgene and thiophosgene, respectivly, gave the derivatives 36 and 37 of the new 1 ,3-dithiolo[ 4,5-g]pteridine ring system. Ribosylation of 12 afforded a 6,7-bis-S-riboside (40) in high yield
Pteridines CIX
No full textA simple direct method for the synthesis of lumazine-6,7-diamines (9, 25-27) from uracil-5,6-diamines (10-13) and methyl cyanoformimidate (24) was found. Various nucleophilic displacement reactions were performed with 7-chloro-1,3-dimethyllumazine-6-amine (17) leading to new 6,7-disubstituted 1,3- dimethyllumazine derivatives (18-23)
Synthesis and Properties of Condensed Lumazine-Ringsystems
No full text1,3-Dimethyllumazine-6,7-diamine (1) and its monomethyl -(3,4) and monophenylamino (5) derivates are interesting starting materials for the synthesis of imidazo[4,5-g] (6-22) and pyrazino[2,3-g]lumazines (23-26). Ringclosure proceeds under relative drastic conditions and the resulting reaction products are highly fluorescent. Methylation of 5,7-dimethyll-imidazo[4,5-g)lumazine (6) led to an isomeric mixture of the 1- (17) and 3-methyl derivatives (7) which could be separated chromatographically. Their structural assignment was based on unambiguous syntheses heating 4 and 3, respectively, with formamide under reflux for ringclosure. The newly synthesized compounds have been characterized by 1H-NMR and UV-spectra as well as elemental analyses
Ethanol and its Halal status in food industries
No full textBackground: Ethanol is an important organic solvent and substrate which extensively used in research and industries. It is the main ingredient produced during fermentation of carbohydrates derived from fruits and other biomass substances. Halal status of ethanol is controversial and it is rational use is ambiguous.
Scope and Approach: In this review, the issue of ethanol in food industries is addressed. Ethanol is a sensitive, controversial and main issue in the production of Halal (Permitted, Allowed) products. Setting the limit of ethanol in Halal food industries is needed to facilitate food production and complied with certain religious demands. This review gives an overview of ethanol, types, application, advantages, and disadvantages. An attempt to set a limit of ethanol in food industries, supported by scientific facts and Islamic rules, is described.
Key Findings and Conclusion: Halal status of ethanol is highly controversial but rarely classified based on its source and concentration. Any ethanol produced by anaerobic fermentation and ranging between 1 and 15% is considered to be Haram (non-Halal, Forbidden), whereas ethanol produced by natural fermentation and less than 1% is considered as preserving agent and its Halal status is allowed. Any ethanolic solution higher than 15% is treated as a toxic solution but still could be used in industries, meanwhile, an ethanolic solution prepared by dilution from absolute or denatured ethanol is allowed for industrial used but toxic for human consumption. However, any concentration varied from 0.1 to 100% prepared with the intention to be used as a beverage drink is consider non-Halal
Reevaluating the halal status of Carmine (E120): A scientific and Islamic legal review
Full text linkCarmine (E120), a natural red dye extracted from cochineal insects (Dactylopius coccus), has long been questioned in its halal status due to its insect origin. Traditional Islamic legal principles generally classify insects as khabīth (impure or repugnant), thus non-halal, based on interpretations rooted in scriptural sources and early dietary norms. However, emerging scientific insights, particularly from entomology and food chemistry, challenge the broad generalisation of this classification. Cochineal insects are herbivorous, feed solely on plants, and are cultivated under clean, controlled conditions. Moreover, the process of producing carmine involves istihālah (chemical transformation), wherein carminic acid undergoes metal complexation, resulting in altered physical and chemical properties that may meet classical criteria for purification. This study reevaluates carmine through an integrative framework that includes Islamic legal principles (such as al-aṣl fī al-ashyāʾ al-ibāḥah and maqāṣid al-sharīʿah), scientific evidence, allergenic considerations, and cultural perceptions (ʿurf). We argue that carmine can be considered halal when derived from herbivorous cochineal insects and processed with high hygiene and transformative techniques. However, due to potential allergic reactions, transparent labelling remains essential to protect consumers and uphold ethical responsibility. This review encourages refining halal certification practices by integrating jurisprudential tradition with contemporary scientific advancements
Cultured meat and halal: A comprehensive analysis from jurisprudence, biology, and ethics
Full text linkWith the growing global Muslim population, dietary practices remain firmly rooted in the principles of halal and tayyib. The rise of cultured meat, produced through cellular agriculture without traditional slaughter, presents significant ethical, spiritual, and jurisprudential challenges. This research evaluates the halal status of cultured meat by examining its production processes, scientific complexities, and alignment with Islamic dietary laws. Through a qualitative review of scientific literature, Islamic jurisprudence, and consumer perspectives, the study focuses on cell-based meat production techniques, health and ethical concerns, and theological positions regarding halal compliance. The findings reveal that cultured meat lacks essential components of natural meat, such as a functional immune system and inherent biological processes, and does not fulfil critical zabiha requirements, including invoking Allah’s name and proper blood drainage. Additionally, the absence of these spiritual and biological elements creates a disconnect from tayyib principles, contributing to scepticism and uncertainty among Muslim consumers. Despite its sustainability potential, cultured meat does not meet the criteria for halal status under current Islamic jurisprudence
The Halal Positive List: Streamlining the Path to Certification
Full text linkHalal certification, a crucial religious guideline for Muslims, has evolved beyond merely excluding meat and alcohol to encompass a wide range of products, including food, cosmetics, chemicals, and pharmaceuticals. This expansion necessitates thorough examinations of ingredient sourcing and processing methods, making certification more complex and time-consuming. The Halal Positive List (HPL) was introduced to streamline this process and developed by Islamic scholars, food scientists, and industry experts. The HPL aims to simplify certification by providing a comprehensive list of pre-approved ingredients, saving time and resources while ensuring consistency and trust. However, challenges remain, particularly in achieving universal acceptance among certifying bodies and addressing the potential toxicity of single-molecule compounds. To enhance compliance, we propose the Halal-Tayyib Positive List (HTPL), which verifies the halal nature and the wholesomeness (tayyib) of ingredients, ensuring they are safe and ethically sourced. The framework categorises ingredients as non-critical, critical, or highly critical, streamlining the halal certification process with a straightforward, standardised approach
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