China 
Africa 
Explore chapters and articles related to this topic
Aldehydes and Ketones. Acyl Addition Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
The product of propane-1,3-dithiol and pentanal is a cyclic dithioacetal, 2-butyl-1,3-dithiane, exactly analogous to formation of an acetal from treatment with a cyclic diol. Six-membered rings with two sulfur atoms are called 1,3-dithianes.
Reactions between lithiated 1,3-dithiane oxides and trialkylboranes
Published in Journal of Sulfur Chemistry, 2021
Basil A. Saleh, Keith Smith, Mark C. Elliott, Gamal A. El-Hiti
Reactions of trialkylboranes with various trisubstituted methanes such as chloroform (CHCl3), dichlorofluoromethane (CHCl2F), chlorodifluoromethane (CHClF2) and 1,1-dichloromethyl methyl ether (DCME) in the presence of a strong base result in the transfer of all three alkyl groups from boron-to-carbon in a single process [9,10]. Even trialkylboranes having a tertiary alkyl group, such as a tert-butyl or thexyl moiety, on reaction with DCME and lithium triethylcarboxide at 25°C, transfer all three groups successfully [9,10]. A reagent with three different leaving groups attached to a central carbon atom could, in principle, be used as an alternative to DCME, opening up possibilities for asymmetric induction to generate enantiomerically enriched chiral tertiary alcohols. Compounds having two sulfur-containing leaving groups have been used successfully to perform up to two 1,2-boron to carbon migrations [11–15], and in principle, a third leaving group could be incorporated to allow a third migration. A potential advantage of using sulfur-based leaving groups might be that stereoselectivity could be controlled, as it can, for example, in reactions of various electrophiles with metalated 1,3-dithiane oxides [16–21]. Such reagents might be able to offer possibilities for the generation of appropriately substituted chiral reagents for reactions with trialkylboranes. However, some basic studies are needed in order to underpin such possibilities.
Novel nondestructive NMR method aided by artificial neural network for monitoring the flavor changes of garlic by drying
Published in Drying Technology, 2021
Yanan Sun, Min Zhang, Ronghua Ju, Arun Mujumdar
The volatile flavor compounds in garlic are mainly composed of chain sulfur compounds, ring sulfur compounds, and non-sulfur compounds. The volatile flavor components contents of fresh, MSWID, and MVD garlic slices are shown in Table 2. Twenty-five kinds of volatile flavor compounds were detected in unprocessed garlic, which contains 14 kinds of sulfur compounds (the relative content of 96. 13%), and mainly, sulfur compounds were diallyl disulfide ether, 1,3-dithiane, diallyl sulfide, allyl sulfide, dimethyl sulfide, methyl allyl sulfide, relative content 52. 52%, 17. 56% and 7.44%, 6.75%, 5.46%, and 4.33%, respectively. The other 11 compounds were non-sulfur compounds, including alcohols, aldehydes, acids, and esters, with a relative content of 3%. A total of 22 compounds were detected in MSWID garlic slices, 8 of which contained sulfur compounds, accounting for 72.57% of the total volatile compounds. A total of 21 compounds were detected in MVD garlic, among which 7 contained sulfur compounds, accounting for 63.83% of the total volatile compounds. As can be seen in Table 2, the types and contents of sulfur compounds in MSWID garlic are very close to those in MVD garlic. After drying, the relative content of diallyl disulfide ether in garlic decreased, which may be because diallyl disulfide ether needs heat energy in the decomposition process.[24,27] This is consistent with the qualitative analysis results of the flavor changes of garlic-dried electronic nose.