Calcium Powder Research Articles

Recovery of Belida Fish Bone Byproduct as a Rich Calcium Powder by Alcali Method

Belida (Chitala sp.) bone is one of the waste from amplang processing which not treated properly yet until now especially in East Kalimantan. One type of the usage of this waste is processed to fish bone powder as calcium source. The aim of this study was to determine the best treatment (boiling frequency) to produce belida fish bone powder which the best characteristics based on highest calcium content. The processing applied alkali method (used NaOH) to produce belida fish bone powder. The treatment of this study was boiling frequency, i.e. P1 (once boiling), P2 (twice boiling), P3 (three times boiling), and P4 (four times boiling) with 30 minutes on each boiling. Observed parameters in this study were moisture content, ash content, protein content, fat content, calcium content, phosphor content, pH and whiteness. The results showed that four times boiling gave the best result with the highest calcium content 31.31%. The range of calcium content was 28.25%-31.31%. While the range of phosphor content was 3.95%-4.06%.

Recovery of Belida Fish Bone Byproduct as a Rich Calcium Powder by Alcali Method

Belida (Chitala sp.) bone is one of the waste from amplang processing which not treated properly<br />yet until now especially in East Kalimantan. One type of the usage of this waste is processed to fish bone<br />powder as calcium source. The aim of this study was to determine the best treatment (boiling frequency)<br />to produce belida fish bone powder which the best characteristics based on highest calcium content. The<br />processing applied alkali method (used NaOH) to produce belida fish bone powder. The treatment of this<br />study was boiling frequency, i.e. P1 (once boiling), P2 (twice boiling), P3 (three times boiling), and P4 (four<br />times boiling) with 30 minutes on each boiling. Observed parameters in this study were moisture content,<br />ash content, protein content, fat content, calcium content, phosphor content, pH and whiteness. The results<br />showed that four times boiling gave the best result with the highest calcium content 31.31%. The range of<br />calcium content was 28.25%-31.31%. While the range of phosphor content was 3.95%-4.06%.<br /><br />

DSC and FIB/TEM investigation of calcium and yttrium additions in the sintering of magnesium powder

Powder metallurgy can be used to produce near-net-shape magnesium parts and also allows unique chemical compositions to be achieved that can lead to new alloys with novel properties. However, the surface layer formed on the magnesium powders during processing acts as a barrier to diffusion and sintering is less effective. The layer, formed by reactions with the atmosphere, contains oxides, hydroxides and carbonate hydrates of magnesium. To overcome this barrier, small additions of calcium or yttrium metal powders were made to the Mg matrix. The oxides of Ca and Y are thermodynamically more stable than magnesium oxide, and will disrupt the surface layer. The present work reports the results of investigation by differential scanning calorimetry, and focussed ion beam (FIB) microscopy and transmission electron microscopy (TEM), on the effect of calcium and yttrium additions during the sintering of magnesium powder. FIB examination of sintered Mg–1 wt-% Ca show that secondary phases are located along grain boundaries as well as inside porosity, which confirms the characteristic mechanism of magnesium sintering. A TEM specimen made by a FIB liftout process was also examined by TEM and EDS and indicates that the sintering process was successful, with the elemental distribution being as predicted by sintering.

Formulation, Sensory and Microbial Aspects of Functional Fermented Dairy Product-Synbiotic Dahi

The present investigation was carried out for the formulation of new functional dairy product “synbiotic dahi” and to study its properties. To formulate synbiotic dahi in three different forms, heat treated cows’ whole milk (95°C/5 min. and subsequently cooled to 37°C) was inoculated with probiotic culture L. helveticus MTCC5463 @2.0% v/v. Prebiotic inulin @2.0% along with other functional food ingredients like WPC (whey protein concentrate) @3.0%, NMCP (natural milk calcium powder) @200 mg/100ml was added to prepare a plain synbiotic dahi (blend A). To make synbiotic dahi sweeten, in one form of dahi added non nutritive sweetener sucralose @19.5 mg/100 ml (blend B) and into another form added cane sugar @9.0% w/v (blend C). These different rates of addition of ingredients were decided on the basis of sensory profile evaluation during preliminary studies carried out. These three blends once formulated were compared with control dahi (M) which was made by using cow milk, without any additives and fermented with the same probiotic culture. All the four dahi prepared were stored at 4 ±1°C for the period of 28 days and evaluated for chemical composition and microbiological attributes at an interval of seven days. As all the three forms of synbiotic dahi prepared were acceptable throughout the storage period for all the sensory and biochemical parameters, without noticeable and undesirable changes, along with around 107 to 108 cfu/ml of live count for probiotic culture.

A novel form of spontaneous tool use displayed by several captive greater vasa parrots (Coracopsis vasa)

Parrots are frequently cited for their sophisticated problem-solving abilities, but cases of habitual tool use among psittacines are scarce. We report the first evidence, to our knowledge, of tool use by greater vasa parrots (Coracopsis vasa). Several members of a captive population spontaneously adopted a novel tool-using technique by using pebbles and date pits either (i) to scrape on the inner surface of seashells, subsequently licking the resulting calcium powder from the tool, or (ii) as a wedge to break off smaller pieces of the shell for ingestion. Tool use occurred most frequently just prior to the breeding season, during which time numerous instances of tool transfer were also documented. These observations provide new insights into the tool-using capabilities of parrots and highlight the greater vasa parrot as a species of interest for studies of physical cognition.

A comparative study of nanostructured calcium copper titanate thin film and powder and their properties

Abstract This paper reports on the effect of phase formation on the dielectric behaviour of nanostructured calcium copper titanate (CaCu3Ti4O12) thin film and powder prepared by using the sol–gel method. X-ray diffraction peaks were indexed as a cubic phase belonging to the Im3 space group for both film and powder. The monophase with a highly crystalline nature was obtained at lower temperature for thin film compared with powder. Micrographs of CaCu3Ti4O12 thin film and nanopowder confirmed the presence of nano-dimensional particles. The functional groups and optical properties of both film and powder were characterized by using the Fourier transform infrared spectrum and the photoluminescence spectrum. The CaCu3Ti4O12 thin film showed higher dielectric permittivity than powder, which strongly suggests that nanostructured thin film is a more efficient material than powder for microelectronic devices.

Effect of Oyster Shell Calcium Powder on the Quality of Restructured Pork Ham.

This study was conducted to evaluate the effects of oyster shell calcium powder (OSCP) as a substitute for phosphates in curing agent, on the quality of restructured pork ham. Restructured pork ham was processed under six treatment conditions: T1 (no additives), T2 (0.3% sodium tripolyphosphate), T3 (1.5% NaCl+0.5% whey protein), T4 (1.5% NaCl+0.5% whey protein+0.15% OSCP), T5 (1.5% NaCl+0.5% whey protein+0.3% OSCP), and T6 (1.5% NaCl+0.5% whey protein+0.5% OSCP). Addition of OSCP significantly increased the ash content and pH of restructured pork ham (p<0.05), but did not affect the cooking loss and water holding capacity values of restructured pork ham. Addition of OSCP had no effect on Hunter a and b surface color values of restructured pork ham, but did decrease the Hunter L surface color value (p<0.05). The addition of 0.5% OSCP showed significantly higher chewiness and springiness values of restructured pork ham, compared with the addition of phosphates (p<0.05). In conclusion, the addition of OSCP combined with low NaCl and 0.5% whey protein can be considered a viable substitute for phosphates in the curing agent, when processing restructured pork ham.

KARAKTERISASI FISIKOKIMIA NANOKALSIUM HASIL EKSTRAKSI TULANG IKAN NILA MENGGUNAKAN LARUTAN BASA DAN ASAM

KARAKTERISASI FISIKOKIMIA NANOKALSIUM HASIL EKSTRAKSI TULANG IKAN NILA MENGGUNAKAN LARUTAN BASA DAN ASAM[Physicochemical Characterization of Nano Calcium from Tilapia Bone Extracted by Alkaline and Acid Solution]Vanessa Lekahena1)*, Didah Nur Faridah2), Rizal Syarief2) dan R. Peranginangin3) 1) Fakultas Pertanian, Universitas Muhammadiyah Maluku Utara, Ternate2) Departemen Ilmu dan Teknologi Pangan, Fakultas Teknologi Pertanian, Institut Pertanian Bogor, Bogor3) Balai Besar Penelitian dan Pengembangan Pengolahan Produk dan Bioteknologi, Kementerian Kelautan dan Perikanan, Jakarta Diterima 26 Maret 2013 / Disetujui 29 April 2014 ABSTRACT The utilization of tilapia (Oreochromis niloticus) bones as a source of natural calcium was done by alkaline (NaOH) and acid (HCl) extraction. The extraction process aims to soften the bones are milled using disc mill into nano sized calcium powder or nanocalcium. The objective of this research was to study the physicochemical properties of nanocalcium obtained from alkaline and acid extraction of tilapia bones. The results of physicochemical analysis properties of nanocalcium sample showed that nanocalcium extracted by alkaline solution had better properties than that of the untreated sample and nanocalcium extracted by acid solution. The results was indicated by the higher yield, brighter colors, smaller particle size, and calcium content (20.67%) and phosphorus (10.09%) with a ratio of Ca/P = 2.0. The Fourier Transform Infrared (FTIR) spectra profile indicated the presence of phosphate group (PO43-) at the bands of 469, 563, 603, 961 and 1035 cm-1, and the presence of apatite carbonate group (CO32-) was indicated by intense bands at 873, 1416, 1456 and 1563 cm-1. The morphology of the sampel surface of the alkaline extracted sample was smoother, denser, and the grain size formed were relatively larger. The formed crystalline phases were HAp (hydroxyapatite), carbonate apatite type A [Ca10(PO4)6CO3] and B [Ca10(PO4)3(CO3)3(OH)2] with crystalline degree of 78.4%.

Calcium hydroxyapatite/whitlockite obtained from dairy products: Simple, environmentally benign and green preparation technology

This study presents synthesis and characterization of calcium hydroxyapatite (Ca10(PO4)6(OH)2, CHAp) and whitlockite (Ca18Mg2H2(PO4)14) composite obtained from dairy product. First, calcium containing powders were precipitated from whey permeate by combining the effect of alkaline pH and temperature. Subsequently a calcium containing phase was collected using membrane filtration and spray-dried. Finally, the temperature treatment was applied to eliminate the organic phase and purify calcium containing compounds. The mechanism of thermal decomposition of dairy calcium powder (DCP) was investigated using thermogravimetric analysis coupled with differential scanning calorimetry (TG–DSC). The phase composition, structural and morphological features of the final products were studied by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).

Synthesis and Molecular Structures of Meta-Substituted Arylcalcium Iodides

The reduction of meta-methyl-substituted iodobenzene with activated calcium in tetrahydrofuran (THF) yields [(3-MeC6H4)CaI(thf)4] (1) and [(3,5-Me2C6H3)CaI(thf)4] (2). The reaction of 3-halo-1-iodobenzene with calcium powder leads to the formation of the corresponding post-Grignard reagents [(3-XC6H4)CaI(thf)4] [X = F (3), Cl (4), Br (5), and I (6)]. The synthesis of the thf adducts of 3-methoxyphenylcalcium iodide (7) and β-naphthylcalcium iodide (8) follows the same strategy. All post-Grignard reagents show a characteristic low-field shift for the calcium-bound carbon atoms in 13C NMR spectra. The molecular structures of 1, 2, 4, and 8 show distorted octahedral environments for the calcium centers with the aryl and halide anions in a trans arrangement.

Arylcalcium Iodides in Tetrahydropyran: Solution Stability in Comparison to Aryllithium Reagents

Reduction of para-substituted iodobenzene in tetrahydropyran (THP) with finely dispersed calcium powder yields arylcalcium iodides of the type [(THP)4Ca(C6H4-4-R)I] with R = CH3 (1), Cl (2), Br (3)...

Studies on the processing of ultramicro calcium powder from goosefish(Lophius litulon) bones by enzymatic hydrolysis

Calcium plays an important role in human health.Lack of calcium intake causes many kinds of diseases,especially osteoporosis.Animal bone provides an important way of obtaining calcium.Fishbone is a kind of natural calcium resource,and it has the merits of high absorbability and low side effects on human.Till now,most of researches on utilization of fishbone have focused on the preparation of calcium tablet from seawater fish,such as haddock,using acid or alkali method.Ultrafine comminution technology is widely used in food processing to make ultrafine powder,and is given more attention nowadays.The ultrafine powder has many particular characteristics,such as increasing the utilization rate of materials,improving performances and the quality of products.Absorption of ultra-micro calcium powder with rich nutrition improved with smaller average particle size.Increasing processing of goosefish(Lophius litulon) is associated with a large amount of waste fish bone and fish head,which will cause environment pollution and resource waste as well.How to utilize this kind of calcium source efficiently is now one of the focuses in the field of fish processing.Nevertheless,no research on goosefish bone using ultrafine comminution technology has been found yet.In this study,ultramicro calcium powders were prepared from goosefish bone by enzymatic hydrolysis followed by ultrafine comminution technique,and the bioavailability of the obtained bone powder was investigated as well.The results showed that the removal rate achieved 33.8% under the optimum purification conditions of goosefish bone hydrolized by 1300 U/g alkaline protease at temperature of 50℃,for 2.5 h.Particle size distribution of calcium powders by superfine comminution for 100min was narrow,and the average particle size reached the minimum of 626.9 nm.The results of animal experiments showed that the bioavailability of ultramicro calcium powders of goosefish bone was much higher,and ultramicro calcium powders by superfine comminution for 100min exhibited calcium absorption rates of 79.3%-83.5%,which is obviously higher than that of the calcium carbonate control group.Goosefish ultramicro calcium powder prepared under the optimum conditions had pure white color,good appearance quality,and no peculiar smell with calcium content of 29.5%.It was considered as a kind of safe calcium supplementation of high quality and bioavailability.

Calcium and phosphorus determination in bones of low value fishes, Sardinella longiceps (Valenciennes) and Trichiurus savala (Cuvier), from Parangipettai, Southeast Coast of India

ObjectiveTo investigate calcium and phosphorus levels in the bones of low value fishes Sardinella longiceps (oil sardine) and Trichiurus savala (ribbon fish). MethodsBones and skeletal remains were subjected to alkaline-alcohol treatment for specified period of time and were then dried and pulverized. Calcium and phosphorus levels were determined by both volumetric and instrumental methods using atomic absorption spectroscopy. ResultsVolumetric analysis of calcium and phosphorus were 28.98% and 14.2% in oil sardine; 24.2% and 11.6% in ribbon fish respectively. Atomic absorption spectroscopy analysis of calcium and phosphorus were 32.73% and 17.2% for oil sardine and 27.17% and 10.83% for ribbon fish respectively. Protein level was 4.82% in oil sardine and 3.97% in ribbon fishes. ConclusionsThe findings of the present study revealed that sardine bones are rich in calcium and will be utilized for the production of calcium powder to treat osteoporosis.

Studies on preparation of haddock calcium tablet and its biological utilization

With China’s increasing development of fisheries and aquaculture,there is an annual increase in the manufacture of aquatic products. Processing of aquatic products is associated with a large amount of waste products,in which fishbone and fishhead account for 45%. The waste products had been used as material of fish sauce and hydrolyzed protein,with high cost and complicated processes. How to efficiently utilize this kind of calcium source becomes focus in fish deep processing. Not only in China calcium deficiency is a prevalent nutritional disease,it has attracted the attention of the world because of its serious result. The lack of calcium intake leads to great interest in demand of calcium supplement and calcium fortification. Fishbone is a kind of natural calcium source. Until recently,researches on utilization of fishbone almost focused on freshwater fish,while no research on seawater fish was conducted to study biological effects on calcium supplement and bone fortification. So,investigating the possible use of waste products obtained after processing haddock,the present study prepared haddock bone calcium powder by NaOH and ethanol soaking (alkaline-alcohol method) and prepared haddock bone calcium tablets using the powder in combination with appropriate excipients. The biological efficacy of the haddock bone calcium tablets was investigated using Wistar rats as an experiment model. Results showed that the optimal parameters for the alkaline-alcohol method are as follows: NaOH concentration 1 mol/L,immersion time 30 h,ethanol concentration 60%,immersion time 15 h. The fish powder processed in this way has high quality in color and odor compared with that prepared in acid method. Contents of fishbone powder are as follows: calcium 27.8%,phosphors 12.2%,protein 3.67%,fat 0.44%. A mixture of 4% polyvinylpyrrolidone in ethanol was used as an excipient,and the ratio between full-cream milk powder and filler was 1∶2. Under these conditions,there is no necessity of the use of a disintegrating agent because disintegrating time is less than 12 min. This process provided satisfactory characters for tablets in terms of rigidity and taste. Animal studies showed that the haddock bone calcium tablets at a dose of 2 g/kg·d or 5 g/kg·d significantly increased blood calcium and phosphorus levels and bone calcium content in Wistar rats. Therefore,the haddock bone calcium tablets have a better biological efficacy than the traditional calcium carbonate formulation,promote bone growth,increase bone density and prevent osteoporosis. The absorption rate is crucial for nutrients. High absorption rates are usually directly related to the bioactivity of the nutrient. Although the reasons of high absorption in the rats fed with haddock bone calcium tablets are still unclear,it is suggested that some factors,such as treatment with method of alkaline-alcohol or the vitamin D in the added milk,may play positive roles in increasing absorption ratio. Some natural trace elements such as magnesium,iron and phosphorus may also be responsible for the high bioavailability of calcium derived from haddock fishbone relative to calcium carbonate. These researches provide a more effective way for economic utilization of fish bone derived from marine fish processing.

Post‐Grignard Reagents: Influence of the Coligands L on the Molecular Structures of Phenylcalcium Iodides [(L)nCa(R)I] and Calcium Diiodides [(L)nCaI2

AbstractIodide is a very soft and large anion and as such its extreme ability to be polarized leads to a flat energy surface with respect to the variation of the Ca–I distances in [(L)nCaI2] and [(L)nCa(R)I]. The influence of the donor strength and the bulkiness of the neutral coligands L on the Ca–I distances is studied. The base adducts of calcium diiodide can be isolated after the addition of L to CaI2 or from the Schlenk equilibrium after the direct synthesis of calcium powder with aryl iodides. As L the ethers diethyl ether (Et2O), tetrahydrofuran (thf), tetrahydropyran (thp), 1,2‐dimethoxyethane (dme), 18‐crown‐6 (18C6), bis(methoxyethyl)ether (diglyme), and amines tetramethylethylenediamine (tmeda), and hexamethyltriethylenetetramine (hmteta) are studied yielding the adducts [(thp)4Ca(Ph)I] (1a), [(thf)4Ca(Ph)I] (1b), [(dme)2(thf)Ca(Ph)I] (1c), [(18C6)Ca(Ph)I] (1d), and [(tmeda)2Ca(Ph)I] (1e), as well as [(thp)4CaI2] (2a), [(thf)4CaI2] (2b), [(Et2O)4CaI2] (2c), [(diglyme)(thf)2CaI2] (2d), [(diglyme)(dme)CaI2] (2e), [(dme)2(thf)CaI2] (2f), [(18C6)CaI2] (2g), [(tmeda)2CaI2] (2h), and [(hmteta)CaI2] (2i). For comparison reasons, [(thf)4Ca(Ph)Br] (3a), [(thp)4CaBr2] (4a), [(thf)4CaBr2] (4b), and [(dme)2(AcOH)CaBr2] (4c) with AcOH being acetic acid are included as well. The comparison shows that the coordination number of calcium itself only plays an insignificant role whereas bulkiness and donor strength of L represent the key influences.

Preparation and biological efficacy of haddock bone calcium tablets

To investigate the possible use of waste products obtained after processing haddock, the present study prepared haddock bone calcium powder by NaOH and ethanol soaking (alkalinealcohol method) and prepared haddock bone calcium tablets using the powder in combination with appropriate excipients. The biological efficacy of the haddock bone calcium tablets was investigated using Wistar rats as an experiment model. Results show that the optimal parameters for the alkalinealcohol method are: NaOH concentration 1 mol/L, immersion time 30 h; ethanol concentration 60%, immersion time 15 h. A mixture of 2% polyvinylpyrrolidone in ethanol was used as an excipient at a ratio of 1:2 to full-cream milk powder, without the use of a disintegrating agent. This process provided satisfactory tablets in terms of rigidity and taste. Animal studies showed that the haddock bone calcium tablets at a dose of 2 g·kg−1·d−1 or 5g·kg−1·d−1 significantly increased blood calcium and phosphorus levels and bone calcium content in rats. Therefore, these tablets could be used for calcium supplementation and prevent osteoporosis. Although the reasons of high absorption in the rats fed with haddock bone calcium tablets are unclear, it is suggested that there are some factors, such as treatment with method of alkaline-alcohol or the added milk, may play positive roles in increasing absorption ratio.

Low-cost phantoms for training of stereotactic vacuum-assisted biopsy of the breast

To test low-cost phantoms for training in stereotactic breast biopsy, we prepared eggplant with calcium powder; gelatin and turkey breast with coarse salt, peppercorns, and calcium powder, respectively; and short-bread pastry with salt. Three to 12 cores were harvested with an 11-gauge vacuum biopsy unit. Mammography images were taken before and after biopsy and from the biopsy cores. The pastry phantom provided the best simulation of microcalcifications for stereotactic biopsy with realistic cores, long durability, and short preparation time.

In vitro degradation and cytotoxicity of Mg/Ca composites produced by powder metallurgy

Mg/Ca (1 wt.%, 5 wt.%, 10 wt.% Ca) composites were prepared from pure magnesium and calcium powders using the powder metallurgy method, aiming to enlarge the addition of Ca content without the formation of Mg 2Ca. The microstructures, mechanical properties and cytotoxicities of Mg/Ca composite samples were investigated. The corrosion of Mg/Ca composites in Dulbecco’s modified Eagle’s medium (DMEM) for various immersion intervals was studied by electrochemical impedance spectroscopy measurements and environmental scanning electron microscope, with the concentrations of released Mg and Ca ions in DMEM for various immersion time intervals being measured. It was shown that the main constitutional phases were Mg and Ca, which were uniformly distributed in the Mg matrix. The ultimate tensile strength (UTS) and elongation of experimental composites decreased with increasing Ca content, and the UTS of Mg/1Ca composite was comparable with that of as-extruded Mg–1Ca alloy. The corrosion potential increased with increasing Ca content, whereas the current density and the impedance decreased. It was found that the protective surface film formed quickly at the initial immersion stage. With increasing immersion time, the surface film became compact, and the corrosion rate of Mg/Ca composites slowed down. The surface film consisted mainly of CaCO 3, MgCO 3·3H 2O, HA and Mg(OH) 2 after 72 h immersion in DMEM. Mg/1Ca and Mg/5Ca composite extracts had no significant toxicity ( p > 0.05) to L-929 cells, whereas Mg/10Ca composite extract induced ∼40% reduced cell viability.

칼슘 첨가 마늘 페이스트로 제조한 양갱의 품질특성 및 항산화성

This study was performed to investigate the quality characteristics and antioxidant activity of garlic yanggaeng added with several calcium sources (calcium carbonate, calcium citrate, calcium lactate, mixed calcium and calcium powder). The pH and lightness of calcium-added garlic yanggaeng decreased compared with control. Lightness of garlic yanggaeng added with calcium lactate, calcium carbonate and calcium powder was similar with that of control. As for texture profile analysis, hardness of garlic yanggaeng added with calcium lactate, calcium carbonate and calcium powder was increased compared to control. The antioxidant activities determined by DPPH and hydroxyl radical scavenging activities of the garlic yanggaeng added with calcium lactate, calcium carbonate and calcium powder were significantly higher than those of control. The pungent and taste of garlic were reduced in garlic yanggaeng added with calcium lactate, calcium carbonate and calcium powder. Consumer test showed that the score of overall acceptance was higher in the garlic yanggaeng added with calcium lactate and calcium carbonate, compared to those of other calcium sources. Based on these results, it was suggested that garlic paste added with calcium carbonate or calcium lactate may be useful materials to improve quality of garlic yanggaeng.

Synthesis and derivatization of naphthylcalcium halides as well as degradation in THF solution

The direct synthesis of 1-naphthyliodide and -bromide with calcium powder yields (thf) 4Ca(Naph)I ( 1) and [(thf) 3Ca(Naph)Br] 2 ( 2), respectively. The metathesis reaction of 1 with KN(SiMe 3) 2 gives (thf) 3Ca(Naph)–N(SiMe 3) 2 ( 3). In 2 and 3 very small Ca–C bond lengths of 252.8(4) and 251.4(6) pm, respectively, are observed. These compounds slowly decompose in THF solution via ether cleavage reactions. From this degradation, [(thf) 4CaBr 2] · naphthalene ( 4) crystallizes from THF solutions. Furthermore, decomposition of 1 in THF solution yields ethene and naphthalene whereas intermediate ethenolate undergoes subsequent degradation to an acetylide.