 |
 |
 |
 |
 |
 |
||
 |
 |
 |
 |
 |
| 1 | 1/1 | 返回列表 |
| 查看: 596 | 回復(fù): 0 | ||
跡地oo新蟲(chóng) (初入文壇)
|
[求助]
求助翻譯啊 ，關(guān)于核磁共振分析的 ，急用��！
|
|
The 13C NMR spectra indicated that glucose was in the forms of a-pyranose (2) and b-pyranose (1; Scheme 1) in [BMIM]Cl at room temperature in the absence of GeCl4 (Figure 9 a). However, when 1 equivalent of GeCl4 was added into the mixture, a new peak at d=76.4 ppm appeared (Figure 9b). The ability of heavier main-group elements to accommodate more than eight electrons in their valence shells, thus forming so-called hypervalent or hypercoordinate compounds, is well established.[ 20] The cations of Group 14 elements can be stabilized thermodynamically by introduction of auxiliary NR2 or OR groups, the lone electron pairs of which could, in principle, be capable of bonding to the empty p orbital of the Group 14 element.[ 21] Therefore, we speculated that GeIV interacted with the two O atoms of 1,2-dihydroxy group of a-glucose to form a stable intermediate 3 (Scheme 1). When the 13C NMR spectrum was recorded at 508C, the relative intensity of the peak at d= 76.4 ppm decreased, and two new peaks at d=152.1 and 103.6 ppm appeared. The intensity of the signal at d= 152.1 ppm increased when the reaction was held at higher temperatures (Figure 9d ande) and also increased over time (data not shown). Therefore, this signal was assigned to the 13C-labeled carbon of HMF at the 2-position. Assignment of the signal at d=103.6 ppm was more tricky. Because this signal was found only at 508C, it should be associated to a relatively stable intermediate with a short lifetime along the reaction pathway to HMF. In other words, at higher temperature, the turnover of this intermediate was greatly accelerated. Therefore, we suppose it was from fructose,[22] which indicated that the intermediate fructose was formed through glucose isomerization. Moreover, the signal at d=76.4 ppm was missing at 808C, indicating that the conversion of 3 was fast. As proposed by zhao et al., fructose was formed from glucose through an enediol intermediate catalyzed by GeCl4. [10] Fructose then lost one water molecular to form the fructofuranosyl oxocarbenium ion.[18] Due to the basicity and nucleophilicity of the halide ion (X), the oxocarbenium ion lost HX to form the enolic species through the nucleophile or the base pathway, followed by loss of two water molecules to form HMF. Our results also suggested that increasing the reaction temperature would enhance the interaction of glucose and GeCl4, and thus promote a ring-opening step of the intermediate 3 to form the straight-chain intermediate 4 through hydrogen transfer, which could be enolated to form 5, followed by the release of GeCl4 to give fructose (Scheme 1). At 80 8C, three new signals at d=56.1, 110.9 and 124.3 ppm appeared, which were attributed to C6, C4 and C3, respectively, of HMF. A new peak at d=80.1 ppm was also observed at 80 8C and 100 8C, which was attributed to a byproduct formed during the reaction. |
回復(fù)此樓» 猜你喜歡
0703化學(xué) 305求調(diào)劑
已經(jīng)有6人回復(fù)
-
一志愿211，0703化學(xué)310分求調(diào)劑
已經(jīng)有3人回復(fù)
-
廣西大學(xué)材料導(dǎo)師推薦
已經(jīng)有5人回復(fù)
-
化學(xué)調(diào)劑
已經(jīng)有5人回復(fù)
-
資源與環(huán)境 調(diào)劑申請(qǐng)(333分)
已經(jīng)有4人回復(fù)
-
311求調(diào)劑
已經(jīng)有14人回復(fù)
-
269專碩求調(diào)劑
已經(jīng)有4人回復(fù)
-
085600材料與化工306
已經(jīng)有3人回復(fù)
-
一志愿西安交通大學(xué)材料工程專業(yè) 282分求調(diào)劑
已經(jīng)有12人回復(fù)
-
材料求調(diào)劑
已經(jīng)有5人回復(fù)
找到一些相關(guān)的精華帖子，希望有用哦~
求助usp中的翻譯
已經(jīng)有7人回復(fù)
- 新人第一次發(fā)帖，求大神幫我分析一下這個(gè)核磁的問(wèn)題！感激不盡！
已經(jīng)有20人回復(fù)
- 氫譜核磁與樣品濃度關(guān)系
已經(jīng)有7人回復(fù)
- 核磁氫譜的分析
已經(jīng)有5人回復(fù)
- 核磁共振 氫譜和碳譜
已經(jīng)有4人回復(fù)
- 請(qǐng)問(wèn)哪里可以做固體核磁？
已經(jīng)有6人回復(fù)
- 求助英語(yǔ)句子結(jié)構(gòu)分析和翻譯
已經(jīng)有7人回復(fù)
- 求英語(yǔ)翻譯�。。�！有急用�。。“萃邪萃小�
已經(jīng)有3人回復(fù)
- 英文文獻(xiàn)中的一句話，求助翻譯，句子結(jié)構(gòu)分析！
已經(jīng)有7人回復(fù)
- 求微普解析化合物結(jié)構(gòu)
已經(jīng)有3人回復(fù)
- 藥物分析方面資料翻譯求助
已經(jīng)有2人回復(fù)
- 高金幣跪求英語(yǔ)翻譯成西班牙語(yǔ)，懇求懂西班牙語(yǔ)的幫忙，文章急用�。�！
已經(jīng)有14人回復(fù)
- NTSYS軟件做聚類分析圖時(shí)，能把圖片編輯成像MEGA軟件做出的效果嗎？
已經(jīng)有9人回復(fù)
- 核磁碳譜峰值不明顯的原因及解決方法
已經(jīng)有6人回復(fù)
- 【求助】一種有機(jī)氣體，兩種無(wú)機(jī)氣體能否用一個(gè)色譜柱分開(kāi)？急用，望各位前輩指教
已經(jīng)有9人回復(fù)
- 【求助】13C-NMR中，55ppm的季碳是什么呀？
已經(jīng)有7人回復(fù)
- 【求助】求高手翻譯，急用，合適者獎(jiǎng)勵(lì)100金幣，多謝了
已經(jīng)有5人回復(fù)
- 【求助】請(qǐng)問(wèn)“色譜柱老化”翻譯成英文怎么說(shuō)啊?
已經(jīng)有3人回復(fù)
- 【求助】請(qǐng)教：質(zhì)譜，翻譯問(wèn)題？
已經(jīng)有4人回復(fù)
- 【求助】請(qǐng)教幾個(gè)模糊物元分析方法專業(yè)詞匯的翻譯【求助完畢】
已經(jīng)有6人回復(fù)
點(diǎn)擊這里搜索更多相關(guān)資源科研從小木蟲(chóng)開(kāi)始，人人為我，我為人人
相關(guān)版塊跳轉(zhuǎn)
我要訂閱樓主 跡地oo 的主題更新
| 1 | 1/1 | 返回列表 |
| 最具人氣熱帖推薦 [查看全部] | 作者 | 回/看 | 最后發(fā)表 | |
|---|---|---|---|---|
|
[考研] 311求調(diào)劑 +13 | 冬十三 2026-03-15 | 14/700 |
|
|---|---|---|---|---|
|
[基金申請(qǐng)] 山東省面上項(xiàng)目限額評(píng)審 +3 | 石瑞0426 2026-03-19 | 3/150 |
|
|
|
[考研] 0703化學(xué)調(diào)劑 +4 | 妮妮ninicgb 2026-03-21 | 4/200 |
|
|
|
[考研] 材料學(xué)碩301分求調(diào)劑 +6 | Liyouyumairs 2026-03-21 | 6/300 |
|
|
|
[考研] 302求調(diào)劑 +12 | 呼呼呼。。。。 2026-03-17 | 12/600 |
|
|
|
[考研] 332求調(diào)劑 +4 | ydfyh 2026-03-17 | 4/200 |
|
|
|
[考研] 265求調(diào)劑 +9 | 梁梁校校 2026-03-17 | 9/450 |
|
|
|
[考研] 328求調(diào)劑，英語(yǔ)六級(jí)551，有科研經(jīng)歷 +4 | 生物工程調(diào)劑 2026-03-17 | 8/400 |
|
|
|
[考研] 一志愿武理材料305分求調(diào)劑 +6 | 想上岸的鯉魚(yú) 2026-03-18 | 7/350 |
|
|
|
[考研] 295求調(diào)劑 +4 | 一志愿京區(qū)211 2026-03-18 | 6/300 |
|
|
|
[考研] 290求調(diào)劑 +7 | ^O^乜 2026-03-19 | 7/350 |
|
|
|
[考研] A區(qū)線材料學(xué)調(diào)劑 +5 | 周周無(wú)極 2026-03-20 | 5/250 |
|
|
|
[考研] 一志愿華中農(nóng)業(yè)071010，總分320求調(diào)劑 +3 | 困困困困坤坤 2026-03-20 | 3/150 |
|
|
|
[考研] 一志愿 南京航空航天大學(xué)大學(xué) ，080500材料科學(xué)與工程學(xué)碩 +5 | @taotao 2026-03-20 | 5/250 |
|
|
|
[考博] 申博26年 +3 | 八6八68 2026-03-19 | 3/150 |
|
|
|
[考研] 334求調(diào)劑 +3 | 志存高遠(yuǎn)意在機(jī)?/a> 2026-03-16 | 3/150 |
|
|
|
[考研] 293求調(diào)劑 +11 | zjl的號(hào) 2026-03-16 | 16/800 |
|
|
|
[考研] 301求調(diào)劑 +4 | A_JiXing 2026-03-16 | 4/200 |
|
|
|
[考研]
 11408 一志愿西電，277分求調(diào)劑
+3
|
zhouzhen654 2026-03-16 | 3/150 |
|
|
|
[考研] 機(jī)械專碩325，尋找調(diào)劑院校 +3 | y9999 2026-03-15 | 5/250 |
|